摘要:

Analyst in the sky satellite-based remote sensing In April NASA scientists released remarkable new images the Ærst from the Terra satellite launched in December last year. The data Øowing back from Terra and similar missions to be launched over the next few years promises a revolution in our understanding of the Earth's climate and environmental systems. Scientists have been successfully using remote sensing (RS) from space to monitor and study the Earth for more than 30 years. The data sent back by these instruments have helped researchers build realistic models of environmental processes and have contributed signiÆcantly to our understanding of complex phenomena such as ozone depletion and climate change. Increasingly remote sensing1 technologies are employed alongside geographical information systems (GIS) for long-term monitoring of environmental parameters; short-term Box 1 The Terra Mission The Terra satellite was launched by NASA from the Vandenberg Air Force Base California on 18 December 1999.Flying in a sun-synchronous orbit it crosses the equator at 10.30 in the morning (hence the ofÆcial name EOS AM-1) when cloud cover over land is at a minimum. Terra is carrying Æve instruments (1) The Moderate Resolution Imaging Spectroradiometer (MODIS) an imaging spectrometer that observes in 36 different wavelengths. (2) The Advanced Spaceborne Thermal Emission and ReØection Radiometer (ASTER) is a collaboration between the US and Japan. With its 14 spectral bands extremely high spatial resolution and 15 m long-track stereo capability ASTER is Terra's zoom lens.(3) The Multi-angle Imaging Spectroradiometer (MISR) is a new type of instrument that has never been Øown in space before. MISR has nine digital cameras each looking in a different direction. An area can be imaged at all nine angles in only seven minutes. It has a track 400 km wide and can see objects as small as 275 m. (4) The Measurements of Pollution in the Troposphere (MOPITT) is a new type of instrument designed by an international team led by Canada. It is the Ærst instrument to make simultaneous measurements of carbon monoxide and methane. (5) The Clouds and the Earth's Radiant Energy System (CERES) is a scanning radiometer with twice the resolution of previous designs.Terra carries two identical instruments one operating in a cross-track scan mode and the other in a biaxial scan mode. Data from all Terra's instruments are fed back to the EOS Operations Centre at the Goddard Space Center Greenbelt MD where they are processed and made available as science data products for users worldwide. Data is available at NASA's Distributed Active Archive Centers within 90±120 days. Terra will be followed by a series of satellites to be launched by NASA over the period to 2012. The Ærst of these is a sister satellite called Aqua (EOS PM-1) to be launched later this year which will Øy in a sun-synchronous polar orbit ascending northward across the equator in the afternoon. These will be followed in four years time by EOS AM-2 and EOS PM-2.This journal is # The Royal Society of Chemistry 2000 assessment and mapping; and detecting seasonal climatic changes and changes in ecosystems. They offer an accurate and cost-effective means of gathering environmental data. Present remote sensing devices are still pretty primitive however the imaging equivalent of the box brownie. A new generation of more sensitive remote sensing instruments combined with dramatic increases in computing power will allow data to be obtained at much greater detail and resolution. Environmental analysts have a powerful new tool at their disposal. Environmental monitoring applications of satellite RS are numerous and include ozone and stratospheric chemistry; land ecosystems and hydrology; and the study of polar and glacier regions (``cryospheric systems'').This article focuses on three areas with a strong analytical component aerosols and tropospheric chemistry; clouds and climate change; and ocean remote sensing. Focus Next generation satellites Over the next 10±15 years environmental remote sensing applications will be dominated by two missions the NASA-sponsored Earth Observing System (EOS) and the European Envisat. NASA began planning the EOS in the early 1980s and it is now part of the US Global Change Research Program.2 EOS consists of three components a space-based observing system; a scientiÆc research programme; and a Data Information System (EOSDIS). EOS will comprise a series of satellites to be launched by NASA and its international partners through to the year 2012 the Ærst of which was the Terra satellite launched last December (see Box 1).EOS's instruments are designed to give complementary measurements of the Earth's processes and will be operational for at least the next 18 years. EOSDIS processes and stores incoming data and makes them 41N J. Environ. Monit. 2000 2 Focus available to the research community and other users as data products. The European Space Agency will launch Envisat-1 an advanced polarorbiting Earth observation satellite in June 2001. Continuing the data measurements begun under the ERS-1 and ERS-2 satellites Envisat will support Earth science research and allow monitoring of environmental and climatic changes (see Box 2).The ERS-1 mission was ended on 10th March this year by a failure in an on-board control system after nine years of service over three times its planned lifetime.3 ERS-2 launched in 1995 took over the operational services of ERS-1 in 1996 and remains in excellent condition. Both missions feature an advanced imaging spectrometer as their Øagship instrument. These are the Moderate Resolution Imaging Spectrometer (MODIS) on EOS and the MEdium Resolution Imaging Spectrometer (MERIS) on Envisat. Imaging spectrometers are Øexible instruments with a wide range of potential remote sensing applications including measurements of ocean colour cloud height water vapour total column and aerosol loads over land and water.4 Aerosols and tropospheric chemistry Satellite remote sensing has been applied to the study of the stratosphere (upper atmosphere) for more than 30 years.Our understanding of the troposphere (lower atmosphere) is much less evolved Box 2 Envisat Envisat is the next generation of European earth observation satellite due to be launched in June 2001. The Envisat-1 satellite will carry ten instruments of which the most signiÆcant for environmental analysis are (1) Advanced Along Track Scanning Radiometer (AATSR) will continue the precise sea surface temperature (SST) measurements begun under the ERS-1/2 missions. This will produce a unique 10 year near-continuous dataset at the levels of accuracy required for climate research (0.3 K or better).(2) Microwave Radiometer (MWR) has evolved from instruments Øown previously on ERS-1/2. It will be used to measure the integrated atmospheric water vapour column and cloud liquid water content as correct terms for the radar altimeter. Data will also be used in surface energy budget investigations. (3) The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a Fourier transform spectrometer for measuring high-resolution gaseous emission spectra in the upper atmosphere. It operates in the near to mid-infrared where many of the atmospheric trace gases have important emission features. (4) Medium Resolution Imaging Spectrometer (MERIS) is an imaging spectrometer that measures the solar radiation reØected by the Earth.It has a ground spatial resolution of 300 m in 15 spectral bands and is programmable in width and position in the visible and near infrared. It will be used primarily in ocean colour measurements. (5) The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) will perform global measurements of trace gases in the troposphere and stratosphere. It will continue and enhance the measurements made by the Global Ozone Monitoring Experiment (GOME) which has been Øying on ERS-2 since 1995. Adapted from the Envisat website at http://envisat.estec.esa.nl 42N J. Environ. Monit. 2000 2 however partly because the troposphere is so complex. Phenomena such as storms forest Æres lightning and manmade pollution emissions all contribute to this complexity.There are currently few data sets of tropospheric chemical components an important requirement in understanding the contribution of tropospheric chemical processes in air quality and climate change. Ground-based datasets are of little use for modelling studies because of the troposphere's great variability. Only space-based measurements can provide comprehensive global time series for troposphere components. Over the next Æve years data from EOS's MOPITT and Envisat's MERIS combined with concerted modelling efforts will help create the Ærst global and long-term picture of the composition of the lower atmosphere. The Canadian MOPITT instrument is the Ærst to simultaneously monitor carbon monoxide and methane two important tropospheric gases.5 MOPITT aims to determine the total amount of carbon monoxide and methane within a vertical column and for carbon monoxide measurements at different altitudes as well.Infrared radiation originating from the Earth's surface is measured and the components radiated from carbon monoxide and methane are isolated using gas correlation spectroscopy. Since methane has an atmospheric concentration of around 1.7 parts per million and carbon monoxide only around 1 part in 10 million the instruments need to be extremely accurate. MOPITT collects data from pixels about 22 km square small enough to detect emissions from individual cities. With a 600 km wide track it can cover the whole of the Earth's surface every 5 days.Since the measurements are in the infrared range data can be collected during the night as well as during daylight. The European MERIS when it is launched next year will also have the capacity to evaluate tropospheric aerosol properties including optical thickness and type6 Satellite data will provide atmospheric chemists and other scientists with highly detailed maps of tropospheric composition. Comparisons of these data over weekly monthly and annual timescales are expected to provide signiÆcant contributions to our understanding of weather seasons and long-term climatic change. Early results from MOPITT have shown signiÆcant variations in carbon monoxide within the Indian sub-continent for example with the Himalayas having low values and lower altitude regions to the south having high values that stream out across the Bay of Bengal.7 Clouds and climate change Radiation and clouds strongly inØuence our weather and climate.4 The effects are so signiÆcant that clouds are second only to greenhouse gases in terms of their effect on long-term climate change.The surface temperature of the Earth depends not only on absorbed solar radiation but also on the rate at which energy is reradiated back into space. The rate of reradiation is controlled by both the amount and the vertical distribution of clouds aerosol particles and greenhouse gases of which the most important is water vapour. Low thick clouds reØect incoming solar radiation back into space causing cooling.High clouds trap outgoing infrared radiation and produce global warming. Since the mid-1980s it has become apparent that overall clouds have a net cooling effect on the Earth. But we have yet to explain the different effects observed in different parts of the world. The Clouds and the Earth's Radiant Energy System (CERES) experiment is one of the highest priority scientiÆc satellite instruments developed for EOS.8 CERES is investigating both solar-reØect and Earth-emitted radiation from the top of the atmosphere to the Earth's surface. Cloud properties are determined using simultaneous measurements by other EOS instruments such as MODIS. For climate change analysis CERES will build on observations begun under previous missions such as the Earth Radiation Budget Experiment (ERBE) of the 1980s.Measurements of radiative Øuxes at the top of the atmosphere (TOA) are analysed using the same algorithms as for ERBE data. CERES is expected to double the accuracy of radiative Øuxes at TOA and the Earth's surface. It will also provide the Ærst longterm global estimates of the radiative Øuxes within the Earth's atmosphere. The consistency of cloud property data and radiative Øux estimates should also be improved. Initial data from Terra and a similar instrument aboard the Tropical Rainfall Measuring Mission (TRMM) launched in 1997 suggest that CERES instruments are a substantial improvement over those of ERBE.9 Similar information on cloud properties (volume height optical thickness albedo) and on aerosols will be available from MERIS.AATSR another Envisat instrument will provide information on cloud coverage water/ice discrimination and particle size distribution while the MWR will produce total column measurements of water vapour and liquid water (see Box 2). Over the next Æve years satellitebased remote sensing should give us a much better understanding of the radiative and physical properties of clouds which in turn should provide a clearer picture of their role in climate change. Global observation will generate new data for improving seasonal-to-interannual climate forecasts including the cloud and radiative aspects of periodic events such as El Ninƒo.Global data on the surface radiation budget can also be used to evaluate the radiative effects and climatic impact of natural events such as volcanic eruptions and major Øoods and droughts. And by providing better estimates of radiative Øuxes within the atmosphere and the earth's surface remote sensing will help us understand the trends and patterns of changes in regional land cover biodiversity and agricultural production. How blue is the ocean? Major uncertainties remain about the amount of carbon stored in the ocean and the biosphere and about the Øuxes between these reservoirs and the atmosphere.4 In particular there is an important need for better information on the spatial distribution of biological activity in the upper ocean and its temporal variability especially in the case of oceanic phytoplankton biomass which has an important role in Æxing CO2 through photosynthesis.On a global scale marine phytoplankton consume Æfty thousand million tonnes of carbon per year–enough to be a signiÆcant factor in climate models. While phytoplankton distribution cannot be seen directly from space it can be calculated from concentrations of chlorophyll-a which can be measured in the visible part of the spectrum. Hence satellite measurements of ocean-colour data have emerged as an important tool for studying the ocean carbon cycle and the role of the ocean in climate change. Ocean colour data also has applications in meteorology and the scientiÆc analysis and measurement of the coastal zone including Æsheries management monitoring of algal blooms and coastal pollution.The Ærst observations of ocean colour from space were carried out by the experimental US Coastal Zone Colour Scanner (CZCS) from 1978 to 1986 aboard NASA's Nimbus-7 satellite. This instrument provided a wealth of new information about the distribution and seasonal variability of biological activity. After a considerable gap due to lack of an operational instrument ocean colour Focus data is now again available from the Japanese OCTS and the French POLDER instruments both launched in 1996 and from NASA's SeaWiFS satellite launched in 1997.This instrument is now providing complete global coverage of the oceans every two days. In addition to MERIS and MODIS other key missions for ocean colour data over the period 2000±2005 will be GLI a mission being prepared by the Japanese Space Agency; and the French POLDER-2. MERIS will provide data with improved spectral and spatial performance. This results from the use of several near infrared channels to perform atmospheric corrections and several narrow visible channels to compute radiance values. By including advanced aperture radar radar altimeter ocean colour and ocean temperature measurements together on the same platform Envisat offers exciting opportunities for synergistic measurements. MERIS's measurements of ocean colour will be combined with those of AATSR on sea surface temperature and ASAR (Advanced Synthetic Aperture Radar) on sea surface roughness.Ocean observations require global spatial coverage at a resolution of 4±8 km a revisit frequency (temporal resolution) of 3±5 days and a minimum of three visible and two infrared channels. The temporal resolution of these instruments is typically 15% per day and integration of data from several instruments on different satellites is needed to achieve the resolutions required. With three instruments around 60% of the ocean surface can be observed every four days. Inland water bodies and marine coastal zones have characteristics at the spatial scale ranging from several tens to several hundreds of metres.10 This requires much higher resolution than present ocean colour instruments such as SeaWiFS.As well as the EOS's MODIS major advances in coastal zone imaging are expected from MERIS and GLI. Seeing through the data As the next generation of earth observation satellites comes on-stream attention is now shifting from collecting the data to how to use it. EOS Envisat and similar missions will generate huge amounts of data of the order of terabytes per day. Scientists are keen to 43N J. Environ. Monit. 2000 2 Focus ensure they utilise this data effectively so that they don't miss any pearls of wisdom enclosed within. Three trends are apparent. Firstly researchers are looking to increase coordination between missions.Although satellites such as EOS and Envisat compete to some extent especially in the supply of commercial data products it is in everyone's interests to ensure that the datasets are as comprehensive as possible. International forums are now emerging to coordinate data collection efforts so as to ensure satellite resources are used effectively. In ocean colour monitoring for example the International Ocean Colour Coordination Group (IOCCG) has taken on this role.10 Secondly with an increasing array of instruments available researchers are focusing on how to integrate and interpret data from multiple sensors using so-called data fusion techniques. NASA scientists demonstrated the approach at their Ærst showing of the Terra data in April.Combining images from MODIS MOPITT CERES and other Terra instruments they clearly 44N J. Environ. Monit. 2000 2 showed how concentrations of gases and aerosols over India are clearly related to topography and population and alter the way sunlight is reØected over the region.7 Thirdly the increasingly large and detailed data sets demand continuing investment in analysis and product development. Algorithms are essential to the accurate and timely interpretation of the data collected. In some cases backward compatibility with previous data sets is also a key consideration as for example in the ERBE/CERES analyses. As satellite coverage and resolution increases and algorithms become more sophisticated more specialised data products are being produced focusing for example on particular parameters or geographical locations (Tables 1 and 2). References and Notes 1 Remote sensing is used here to mean satellite remote sensing. Earth-based remote sensing techniques are not covered. 2 Moderate Resolution Imaging Spectroradiometer NASA 1998. See also MODIS website http:// modis.gsfc.nasa.gov 3 European Space Agency Press Release No 18-2000 13 March 2000. http:// earth.esa.int 4 EOS Science Plan Michael D. King Reynold Greenstone eds NASA Goddard Space Flight Centre 1999. Available at http://eospso.gsfc.nasa.gov 5 Measurement of Pollution in the Troposphere Canadian Space Agency 1998. See also MOPITT website http:// www.eos.ucar.edu/mopitt/home.html 6 Characterisation of aerosols over land with space sensors Centre for Earth Observation 1999. Available at http:// www.ceo.org 7 NASA News Release First Images Press Conference 19 April 2000 Available at http://terra.nasa.gov/Events/FirstImages/ 8 Clouds and the Earth's Radiant Energy System NASA 1998. 9 For information on TERRA data products see http://eosweb.larc.nasa.gov 10 Characterisation of inland and coastal waters with space sensors Centre for Earth Observation 1999. Available at http://www.ceo.org Mike Sharpe

ISSN:0960-7919    

DOI:10.1039/b003621h

出版商:RSC    

年代:2000

数据来源: RSC

摘要:

Legislation BeneÆts of air emission ceilings The beneÆts of proposed emission ceilings for four key air pollutants ``appear likely'' to exceed their costs according to a recent study published by the European Commission. Under the controversial proposals the Commission is planning to set national emission ceilings for sulfur dioxide nitrogen oxides ammonia and hydrocarbons as part of its strategy to tackle acidiÆcation eutrophication and ground-level ozone. Consultants from Austria's IIASA and the UK's AEA Technology compared the costs and beneÆts of different emission ceilings representing high medium and low ambition against a reference scenario based on expected reductions without further EU legislation. The Commission's proposal equates to a medium scenario under which costs would amount to 17.5bn annually 13% higher than under current legislation.The beneÆts of meeting the proposal's targets are estimated at between 117bn and 32bn depending on how health improvements are measured. Other Ægures produced by the Commission for the European Parliament claim the tighter emission ceilings will prevent an extra 4000 early deaths annually through reduced exposure to ozone and secondary particulates. These Ægures are relative to less ambitious reduction targets under last year's UNECE agreement. Meanwhile a recent report from Norway estimates that particulate air pollution is costing the country 13.4 billion per years and causing thousands of premature deaths.Using World Health Organisation criteria the study says total deaths could be as high as 2000 per year with fatalities dieing on average seven years prematurely. The scale of estimated health effects is similar to that suggested by a British survey two years ago but much larger than that of a French study last year [JEM 1999 1(3) 43N]. European Commission ``Economic Evaluation of a Directive on National Emissions Ceilings for Certain Atmospheric Pollutants'' Part A Costeffectiveness; Part B BeneÆts.'' Available at http://europa.eu.int/comm/ This journal is # The Royal Society of Chemistry 2000 environment/enveco/; Norwegian Pollution Control Agency ``Health Effects and Socio-economic Costs of Air Pollution'' www.sft.no/publik/1718/ TA1718.html CEPA now in force The new Canadian Environmental Protection Act (CEPA) became law in April.Approved by Parliament in September last year the Act updates Canadian law to reØect advances in scientiÆc knowledge and places a new emphasis on public accountability and transparency. CEPA introduces strong new powers and tools in Æve priority areas promoting cleaner air and water; managing toxic substances; encouraging public participation; preventing and responding to environmental emergencies; and enforcement. One important provision is for the government to be able to request the development and implementation of pollution prevention plans for facilities that manufacture or use substances deÆned as ``toxic'' under the Act.Welcoming the new legislation Environment Minister David Anderson said CEPA was ``one of the most advanced environmental laws of its kind in the developed world'' and would be an ``important tool in preventing the release of toxic substances into our air and water''. CEPA website www.ec.gc.ca/ CEPARegistry New drinking water monitoring The EPA is to extend the monitoring requirements for drinking water to underground sources in order to protect against disease-causing viruses and bacteria such as E. coli. The proposed rule the Ærst to extend such protections to underground sources of drinking water is expected to prevent over 115,000 illnesses a year. At present only public water systems supplied by surface waters such as rivers lakes and streams are required to apply chemical treatments to prevent News waterborne diseases.However new research indicates that groundwater supplies can also be susceptible to contamination from a range of sources including failures in municipal sewage treatment systems and stand-alone septic systems. The new rule introduced under the 1996 Safe Drinking Water Act amendments requires the states to survey all drinking water systems. Groundwater systems at risk of contamination would be required to monitor their sources and take corrective action such as disinfection to address any contamination found. In a related development EPA and other federal agencies have published a report outlining progress with the Clean Water Action Plan introduced by the Clinton administration in 1998.The report notes that the US's 54,000 drinking water systems and 16,000 wastewater systems face funding needs over the next 20 years of a staggering $1 trillion. Furthermore utilities face a funding gap of $23 billion between current spending and the investment needed to replace aging facilities and comply with existing and future federal regulations. The President's FY 2001 budget request includes almost $2.8 billion an increase of $584 million to support key actions in the Plan. EPA Safe Drinking Water Programme www.epa.gov/safewater; ``Clean and Safe Water for the 21st Century'' available at http://cleanwater.gov EPA pushes smog reduction EPA has taken action to implement the rule requiring Eastern states to develop smog-reduction plans.The move followed a ruling by the US Court of Appeals in March upholding Agency's authority to request the plans. Acting on EPA's behalf the Justice Department asked the Court to formally remove the ``stay'' placed on the rule in May last year so that states can Ænalise plans to ensure emission reductions. The move came as the EPA's latest air quality trends report showed continuing increases in levels of ground-level ozone a precursor of smog especially in rural 45N J. Environ. Monit. 2000 2 News areas. Looking at trends over the last ten years the report shows that while the overall picture has improved air quality in some rural areas has worsened especially in the East.Smog concentrations for example increased at 17 of 24 National Park Service monitoring sites. From 1992±1998 Æne particle concentrations increased at 7 of 10 eastern rural monitoring sites. EPA attributes this rural pollution to regional transport smog-forming NOx and Æne particles being carried on the wind hundreds of miles from their origin causing pollution problems several states away. A summary of 1999 air quality trends is expected shortly. Environmental quality Environmental information still lacking We continue to lack the baseline knowledge needed to properly determine the condition of the world's ecosystems according to a recent report from the World Resources Institute an environmental think-tank.Launching its state-of-theenvironment report in Washington DC in April WRI President Jonathan Lash said ``The dimensions of this information gap are large and growing rather than shrinking as we would expect in this age of satellite imaging and the internet. If we are to make sound ecosystem management decisions in the 21st century dramatic changes are needed in the way we use the knowledge and experience at hand and the range of additional information we need''. The report presents a new methodology called Pilot Analysis of Global Ecosystems (PAGE) the Ærst to examine the interrelation of coastal forest grassland freshwater and agricultural ecosystems.Some of the many alarming indicators highlighted by the report include half of the world's wetlands have been lost in the last 100 years; tropical deforestation is running at around 130,000 sq km per year; and around two-thirds of the world's agricultural land is affected by soil degradation. The PAGE report has provided the impetus for the Millenniun Ecosystems 46N J. Environ. Monit. 2000 2 EPA OfÆce of Air Quality Planning and Standards ``National Air Quality and Emission Trends Report 1998'' Available at www.epa.gov/oar/aqtrnd98/ EPA hails NOx trading EPA has published data which it claims shows the success of the emission reduction and trading program for nitrogen oxide (NOx). The program represents the Ærst application of the market-based emissions trading concept to an issue other than acid rain where the approach has been used successfully since 1995 to control sulfur dioxide emissions from power plants.Assessment a plan put forward by governments UN agencies and leading scientiÆc organisations to allow an ongoing monitoring and evaluation of the health of the world's ecosystems. A Guide to World Resources 2000-2001 People and Ecosystems–The fraying web of life World Resources Institute. Available at www.wri.org/wri/wrr2000 Water quality tests Øawed Testing procedures commonly used to evaluate pollution levels in rivers and streams may be underestimating pollution loads by as much as 20% according to scientists at the University of Arkansas.Samples are commonly taken on a monthly basis but pollution load increase dramatically during storms which are rarely accounted for by monthly sampling. The researchers studied six different water quality parameters in two of the state's waterways over a two-year period. Much or most of the load in a stream is transported during storms but is missed without intensive sampling. During one storm in January 1998 for example the measured phosphorus concentrations on the Illinois River surpassed the estimated concentration for the entire previous year based on monthly collection data. Team leader Marc Nelson said the results indicated that ``pollutant load determinations are very sensitive to the The Ozone Transport Commission NOx Budget report for 1999 shows that in participating north-eastern states emissions were reduced 20% below the levels allowed by law and more than 50% below 1990 levels.EPA says the program demonstrates that successful partnering can make substantial reductions in NOx emissions using least-cost approaches and that a market-based cap and trade approach can be applied to interstate air pollution problems besides acid rain. Ozone Transport Commission www.sso.org/otc/ frequency of sampling during storm events. All of the parameters except nitrates have most of their concentrations peak during the Ærst part of a storm''. By sampling storm runoff events at 30 min intervals the researchers were able to develop sub-sampling and data analysis techniques.These were used to determine the minimum sample interval required to determine storm pollutant loads accurately. The optimum sample interval is dependent on the type of pollutant and the size of the drainage basin. The researchers plan to use the data to investigate the role of non-point sources in calculating the total daily maximum load (TDML). Arkansas Water Resources Center Quality Lab manelson@comp.uark.edu Critical loads celebrated Environmental scientists meet in Germany recently to review ten years of the critical loads approach in European environmental policies. The experience was widely seen as highly successful with critical loads having added a new dimension in international air pollution control and contributed to major cuts in transboundary air pollutants.The approach would be given even broader application in the future including controls on persistent organic pollutants (POPs) and heavy metals and better protection for materials and human health. The critical loads concept emerged in the 1980s and is based on the idea that pollution controls should be effectsbased i.e. based on quantitative estimates of an ecosystem's tolerance to pollution. The technique was Ærst applied to policy-making in a 1994 protocol on transboundary SO2 pollution developed by the UN Economic Commission for Europe (UNECE). It has since been applied in a series of UNECE air pollution treaties culminating in the multipollutants multi-effects protocol agreed in 1999.Future directions identiÆed by speakers included dynamic modelling to enable prediction of emission control impacts and the extension of mapping to cover heavy metals and POPs. New elements such as health criteria and Chemical hazards Flame retardants row hots up European manufacturers and environmental groups have clashed bitterly over proposals to ban the use of the brominated Øame retardants (BFRs) PBDE and PBB. The row came as Denmark pushed ahead with plans to phase out BFRs the Ærst European country to do so. Greenpeace said that proposed bans on PBDE and PBB under a draft directive on waste electrical and electronic equipment were ``entirely insufÆcient''.Since these two substances represent only around 12% of all BFRs and have a declining market share the proposals fail to address the real problem Greenpeace said. The group called for the Commission to ban all BFRs by 2004. Manufacturers countered with new evidence from a Swedish study which they claimed conÆrms BFRs reduce overall environmental impact by preventing Æres. Using lifecycle approaches releases of PAHs and dioxins and furans were reported to be ``markedly higher'' from non-Øame retarded televisions than those where BFRs were used. International regulation and the promotion of substitutes are the two main elements of the Danish action effects of Æne particulates could also be introduced. UNECE www.unece.org; International Cooperative Programme on Mapping Critical Loads and Levels www.oekodata.com/IPMapping High UV predicted Scientists at Environment Canada are predicting that average ozone coverage over the northern hemisphere will be 6% less than normal this summer.The forecast is based on recent measurements from Canadian ozone stations and from satellite data showing severe ozone depletion over the Arctic. The thinner ozone layer is expected to increase the ultraviolet-B radiation reaching Earth by 7%. During the winter and spring levels of plan published in April. Support for cleaner technology and development of substitute Øame retardants are also covered in the plan which is due to be adopted by the end of June.The draft strategy breaks new ground by suggesting that all three types of PDBE in commercial use (penta-DBE octa- BDE and deca-BDE) should be phased out rather than just penta-DBE. The Ænal plan will take account of two studies on health and environmental impacts of other BFRs and possible alternatives due to be completed shortly. These could form the basis for voluntary agreements with manufacturers on a national level. Bromine Science and Environment Forum ``LCA Study of Flame Retardants in TV Enclosures'' www.bsef.com; Greenpeace www.greenpeace.org/ ~toxics/hfr.html; Danish EPA www.mst.dk/fagomr/kemi/14030700.doc Pesticides registration; residue monitoring The EU and US are to cooperate on the testing of new pesticides in a bid to reduce the time and expense involved in approving new plant protection products.Using the herbicide News stratospheric ozone above the Arctic declined by a staggering 60%. The Ændings have reinforced concerns that Arctic ozone may continue to decline despite reductions in stratospheric chlorine levels resulting from the Montreal Protocol. The continued reduction in ozone levels may be due to the effects of climate change through variations in wind patterns and temperatures. The measurements of ozone and UV radiation were taken from the NASA ER-2 research plane as part of the Sage Ozone Loss and Validation Experiment (SOLVE) into ozone depletion and atmospheric chemistry over the Arctic. SOLVE involves researchers from Canada Europe Russia Japan and the United States.SOLVE http://cloud1.arc.nasa.gov/ solve/index.html foramsulforon as a test case European and American scientists will undertake parallel reviews and compare their results. The exercise will identify similarities and differences between data evaluation and regulatory requirements and if successful could lead to shared assessments of new pesticides. At the other end of the pesticide application cycle a report on pesticide residues in cereals fruit and vegetables said that an EU monitoring programme is being hampered by lack of resources. The absence of minimum monitoring standards and the low number of laboratories accredited for residue analyses are particular problems the report says.The Commission's own powers to make inspections are limited. An absence of complementary data on diet also hinders the collection of reliable time series data for pesticide intakes the experts say. Meanwhile Denmark is pressing ahead with plans to curb the use of agricultural pesticides that will give it one of the toughest regimes in Europe. The plan aims to cut pesticide use by one-Æfth create no spray zones around water courses and triple the area farmed organically. In a concession to the farming lobby certain uses are to be exempt from the new requirement to phase out all pesticides affecting 47N J. Environ. Monit. 2000 2 News groundwater the source of all Danish drinking water.Plans to ban the use of pesticides in private gardens have been dropped. Pesticide Monitoring Review http:// europa.eu.int/eur-lex/en/com/pdf/2000/ com2000_0098en01.pdf; Danish EPA www.mst.dk US unveils lead strategy Comprehensive measures to safeguard against lead hazards have been announced by the Clinton administration under a strategy designed to virtually eliminate childhood lead exposures within ten years. The most recent data show that in the US nearly one million children under the six–one in 20–have elevated levels of lead in their bodies. Elevated blood lead levels can produce signiÆcant nervous system effects such as reduction in intelligence and attention span reading and learning disabilities and behavioural problems.The strategy calls for action against lead paint hazards in 2.3 million homes with children aged under six. It also calls for greater public education on lead risks strict enforcement of lead paint regulations and early intervention for children known to be at risk. The economic beneÆts from preventing adverse effects of lead on children's health and development are estimated at $8.9 billion. To help implement the plan the President's FY 2001 budgets calls for an investment of $164.5 million including a 50% increase in lead hazard control grants and nearly $13 million in new federal funding for enforcement of lead regulations. ``Eliminating Childhood Lead Poisoning A Federal Strategy Targeting Lead Paint Hazard'' Available at www.hud.gov/lea Public and occupational health Rural communities at risk from pesticides Children and others in farming communities are exposed to higher levels of pesticides than previously thought according to researchers at the 48N J.Environ. Monit. 2000 2 EU resists MTBE move European authorities have no plans to mirror the US EPA's ban on the petrol additive MTBE. EPA says MTBE (methyl tertiary-butyl ether) an additive used in motor fuels is a ``possible carcinogen'' which has caused considerable damage to groundwater. It is proposing to replace the additive with ethanol a non-petrochemical alternative. A spokesperson for the European Commission said that Environment Commissioner Margot Wallstro»m was watching developments in the US with interest but had ``no immediate plans'' to call for similar rules in the EU.In Europe MTBE is used instead as an octane booster and typically only at concentrations of around 1.6% although concentrations of up to 15% are permitted. However the use of MTBE is set to increase dramatically as a result of new EU fuel and air quality laws aimed at curbing benzene. As in the use the EU could soon face a difÆcult trade-off between air quality and groundwater protection. An EUsponsored risk assessment is underway in Finland Europe's heaviest per capita consumer. Brake pads spread copper Vehicle brake pads are a major source of heavy metal pollution Swedish scientists say. In Stockholm alone more than 4 tonnes per year of copper discharges originate from car trafÆc according to a recent survey commissioned by the Swedish EPA.Copper replaced asbestos in brake pads 10±15 years ago. Although brake pads represent only a minor use this application is responsible for the largest spread of copper to the environment the scientists say. The metal is discharged as particulates which account for around a third of annual copper emissions University of Washington. Tests on children of farm workers in Douglas and Chelan counties in Washington State showed more than half had exposures that may have exceeded federal standards even though the children themselves do not work in the Æelds. reaching Stockholm's environment a total of 12±13 tonnes.Lead and zinc particulates from vehicle brake pads also give rise for concern. ``It seems that we have traded a health problem for an environmental problem'' says Bo Bergba» ck of Kalmar University. The study is part of a wider Æve-year research project on metals in urban and forest environments due to be published later this year. Swedish EPA www.environ.se UK hormone disrupters strategy The Environment Agency has called for early action to minimise discharges of chemicals suspected of affecting the hormonal systems of animals and humans. In a long-awaited strategy published in March the Agency advocates reduced emissions of chemicals that are already controlled and may also be endocrine disrupters.New controls on some alkylphenols and steroids are also proposed including the development of environmental quality standards. Both chemicals are released in large quantities from sewage works. Other elements include encouraging industry to implement voluntary reduction measures and reviewing whether more can be done under the national integrated pollution prevention and control regime for industrial plants. The strategy also proposes research targets such as further investigation of the fate and behaviour of natural and synthetic EDCs in different environmental media. The Agency's strategy covers England and Wales. The Scottish EPA is understood to be developing its own strategy along similar lines. Environment Agency www.environmentagency.gov.uk/issues/endocrin.pdf Of the children monitored 56% indicated exposures to azinphos-methyl a chemical used to treat apple orchards that might exceed federal levels. Even for children who lived more than a quarter of a mile from orchards and whose parents were not farm workers the rate of higher exposure was 44%. For phosmet a less toxic alternative to azinphos-methyl only 9% of the farmworker children had test results which suggested federal safety guidelines might have been exceeded. ``We don't know how and if these exposures are affecting children's health'' said Professor Richard Fenske of the University of Washington's School of Public Health and Community Medicine. ``The study shows regulators need to look at exposure standards and determine if they are appropriate''.New French health agency The French government is proceeding with plans for a powerful new environmental health agency after winning backing for the proposal in parliament. The agency will provide independent expert advice to public Research activities HEI sets strategic plan The Health Effects Institute the US research body has unveiled far-reaching plans for research into links between air pollution and human health. HEI's Strategic Plan for 2000±2005 targets three key scientiÆc areas air pollution mixtures health effects of emerging fuels and technologies and impact of air quality regulations. In a departure from its previous approach HEI will no longer focus on single pollutants such as ozone and carbon monoxide.The strategy has a strong international perspective reØecting what HEI says is an increasing need for a scientiÆc base to inform consistency in decision-making in North America Europe and Asia. Within the air pollution mixture theme HEI has targeted three submixtures PM and gaseous pollutants air toxics and diesel emissions. Work in the PM area will investigate toxic components of the PM mixture an essential issue in implementing regulatory standards and the effects or contribution of gaseous pollutants such as ozone to PM effects. Epidemiologic studies of the health effects of PM and gases will be particularly important. Work on air toxics will be broadened to include acute authorities and coordinate the work of three existing agencies.The move follows a report last summer on scientiÆc advice on environment-related health issues in the wake of the controversies over BSE dioxin contamination of animal feed and chemical contamination of soft drinks. The new agency is to be jointly supervised by the environment and health ministries. Early priorities are likely to include Æne particulates dioxins nitrates genetically modiÆed organisms radon and glycol ethers. French Environment Ministry www.environnement.gouv.fr NTP consults on hormone disrupters The Center for the Evaluation of Risks to Human Reproduction (CERHR) of and non-cancer health effects and mechanisms as well as further research to improve estimation of diesel risk.In the area of emerging fuels and technologies HEI will take a more systematic approach. This will involve for example initiating rapid assessments of technologies in terms of pollution emissions carbon dioxide production fuel economy and engine performance. As air pollution declines demand grows for better techniques to assess the beneÆts of efforts to further reduce exposure. The impact of air quality regulations research will focus on issues of accountability including continuing development of the National Morbidity Mortality and Air Pollution Study (NMMAPS) innovative methods of measuring beneÆts and multistakeholder discussions. Health Effects Institute www.healtheffects.org Sulfur standards bring big payback Measurement standards for sulfur in fossil fuels have paid back more than 100-fold according to the US National Institute for Standards and Technology (NIST).In a new economic impact News the National Toxicology Program (NTP) has identiÆed a further eleven chemicals for possible investigation as endocrine disruptors. The chemicals under consideration are 1-bromopropane 2-bromopropane dimethyl methyl phosphonate (DMMP) ethylene glycol glycol ethers glyphosate methanol nicotine phenol thimerosal and toluene. CERHR will prepare dossiers on the chemicals with a view to selecting candidates for detailed review by an Expert Panel later in the year.Selection of candidate chemicals will be based on information on production volume extent of human exposures and published evidence of reproductive or developmental toxicity. Expert Panel meetings will be held in public and the Ændings published in the journal Environmental Health Perspectives. CERHR http://cerhr.niehs.nih.gov study NIST says that the Standards Reference Materials for sulfur have saved the fossil fuel industry $113 for every dollar spent on their development. Fossil fuel producers and users use NIST standards to verify the accuracy of their measurements of sulfur in coal and petroleum products. Improved accuracy of sulfur measurements has increased efÆciency in petroleum production reduced disputes between buyers and sellers of fossil fuels and lowered environmental sulfur emissions.Total economic beneÆts since the standards began in 1984 including estimated beneÆts to 2003 amount to $409 million. These include $401 through improved production efÆciency; $7.5 million from changes in transaction costs; $2.7 million from improved product quality; and $1 million in savings on commercial measurement reference materials. In addition to savings within the sulfur measurement supply chain the study identiÆed a further $78 million in environmental beneÆts. Fine particulate research EPA has awarded $22.55 million in federal grants to seven university 49N J. Environ. Monit. 2000 2 News research centres for intensive studies on Æne particulates.The grants which are part of the Supersites monitoring program will support new techniques for pinpointing the sources formation and transport of Æne particulates. The programme also aims to identify the components of particulate pollution that are most important to health as a basis for costeffective control strategies. EPA OfÆce of Air Quality Planning and Standards www.epa.gov/OAQPS Biosensors light the way New types of chemical sensors which rely on bioluminescence from living cells Publications Nutrients in European waters Worsening problems created by excess nutrients in European ecosystems are documented in a report published by the European Environment Agency. Lakes reservoirs rivers coastal marine waters and terrestrial ecosystems are all affected to varying degrees by nutrient excesses.In most cases the damage varies only by geographic region. Many reservoirs serving essential uses such as public water supplies and irrigation are among the most affected by eutrophication because they are of necessity located close to areas of intense human activity. The report says eutrophication is a major issue in still water environments but even after decades of scientiÆc research there are very few monitoring programmes. In rivers the most widespread pollutant is phosphorus which results in the development of large quantities of seasonal plant growth leading to other types of impact such as perturbed oxygen and pH cycles organic pollution and massive growth of toxic algae.Excessive levels of nitrates observed in many previous studies represent a widespread degradation of river water and locally nitrate concentrations may prevent human uses of water. The frequency and geographic extent of eutrophication phenomena are increasing in coastal waters even in marine areas previously believed to be 50N J. Environ. Monit. 2000 2 could have important applications in environmental monitoring. Prototypes of the cells have already been shown to be sensitive to trace amounts of hydrocarbons and heavy metals in water. Combining elements of genetic engineering and semiconductor technology the sensors utilise the bioluminescence emitted by living cells as they metabolise pollutants.The cells are encapsulated in a porous and transparent sol±gel glass matrix which is Æxed to the top of a light-sensitive semiconductor chip. Faint optical emissions from the cells are ampliÆed by the semiconductor and converted to signals that are recorded on a computer. The strength of the signals can be correlated with pollutant concentrations. unaffected. In terrestrial ecosystems nutrient impacts appear to be serious because of the uncertainty of recovery of the land-based systems leading to losses of species and ecosystems. The application of nutrient reduction policies is patchy says the report. But the authors found it difÆcult to assess the effectiveness of these policies because of the general scarcity of data concerning primary causes emissions and the status of ecosystems.Nutrients in European Ecosystems European Environment Agency Copenhagen 2000. Available at http:// org.eea.eu.int/themes/nature Mediterranean environment under threat Human activity including tourism is putting increasing pressure on the Mediterranean region according to a recent study by the European Environment Agency. EEA says the open waters of the Mediterranean are generally in good condition and most of the diverse ecosystems appear to be healthy. The sea is characterised by a high diversity of marine species and is recognised as one of the richest biotopes in the world with about 8±9% of global seas species. However the presence of so many people along the coastal zones± either as tourists or inhabitants ± puts Current units can detect minute levels of toluene naphthalene PCBs and heavy metals and another to detect environmental estrogens is under development.The sensors which are yet to be tested outside of the lab are being developed by Oak Ridge National Laboratory in collaboration with the analytical instruments manufacturer Perkin Elmer. Potential applications include pollution control systems construction site monitoring and site remediation and monitoring. Oak Ridge National Laboratory simpsonml1@ornl.gov continuous pressure on the region. Only a small percentage of the coastal area is in good condition with an even smaller part adequately protected. About 60% of urban waste disposed in the Mediterranean Sea is still untreated the report says while waters in the open sea are amongst the poorest in the world for nutrients. The worst environmental problem appears to be pollution "hot spots" located generally in semi-enclosed gulfs and bays near important harbours big cities and industrial areas. These pressures seem set to increase in the future. Population in the countries bordering the sea will increase from 450 million people in 1997 to a projected 520±570 million in 2030. While tourism will grow from 135 million visits in 1990 to as many as 235±350 million in 2025. Various aspects of environmental conditions are still poorly documented hampering any cohesive approach to understanding and then solving problems says EEA. Stronger international co-operation is needed under the Barcelona Convention and through the European Union if any headway is to be made in ensuring the viable future of this important ecosystem. State and pressures of the marine and coastal Mediterranean environment European Environment Agency 2000. Available at http://org.eea.eu.int/themes

ISSN:0960-7919    

DOI:10.1039/b003622f

出版商:RSC    

年代:2000

数据来源: RSC

摘要:

Can NRDAs take the environment back to the future? New York's Hudson River stretches over 200 miles from the wilds of Glens Falls to the canyons of Manhattan. Wisconsin's Fox River hosts the largest concentration of paper mills in the world. What the two rivers share is a legacy of PCBs. Both will become the focus of intense scientiÆc economic and legal energy when two giant Natural Resource Damage Assessments (NRDAs) get into full swing next year. Already the U.S. Fish and Wildlife Service has estimated that for the Fox River where historic PCBs contamination has meant Æsh advisories for every species of sport Æsh lost Æshing opportunities total over $100 million in public damages.1 For the Hudson NRDA estimates are much higher. NRDAs are a little known part of the Superfund Law which empower certain federal and state agencies to seek damages for injuries to public natural resources caused by hazardous wastes.The idea is to replace or restore damaged natural resources so that they can continue to be enjoyed by the public. But this simply stated aim makes complex scientiÆc and economic demands. Agencies must assess the extent of the damage and link it to a toxic release; Hudson River The General Electric Hudson Falls plant in northern New York used PCBs in the manufacture of capacitors from 1957 to 1977. It is one of two plants whose discharges contaminated the river. Photograph courtesy US Environmental Protection Agency. This journal is # The Royal Society of Chemistry 2000 devise a restoration plan; and determine the full value of what the public has lost.This value can be large indeed. The Exxon Valdez oil spill the largest and most famous NRDA cost Exxon $1 billion in addition to the clean-up bill of $2 billion. NRDAs at hazardous waste sites have to date been much more modest. Close to 70 sites have been settled for some $177 million,2 with six settlements accounting for most of the expenditure. In Natural Resource Damage Assessments scientists and economists work closely together. Scientists are involved in measuring injury and teasing out the links between contamination and some measure of harm by determining a pathway from the contamination to exposure of the resource. At every step economists are also involved in determining the value of the claim– whether in terms of money or in terms of other natural resources that could replace what has been lost.Challenging science For both the Fox River and the Hudson River scientists will be trying to resolve long-standing disagreements over PCBs fate and transport. In the Hudson River for example,EPAcontends on the basis of its sampling program that large quantities US Focus of PCBs are still washing out of old deposits in the upper part of the river. But General Electric the principle responsible party claims based on its own sampling program that old PCBs deposits are no longer a problem because they are being buried by fresh clean sediment. EPA's efforts compared data from core samples taken in 1994 with data from core samples taken between 1976 and 1984.The data show that about three-quarters of PCBs lost from the pool entered the water column and were redistributed throughout the Hudson River system according to EPA. But GE contends that the agency took too few samples failed to study them in sufÆcient detail compared results from two different and incompatible sampling techniques and misused a key statistic.3,4 Damages to natural resources are judged in comparison to ``baseline'' or what the ecosystem would have been like had it not been for the contamination. But the dynamic nature of ecosystems plays havoc with a simple-minded conception of a stable undisturbed system.For example for the Fox River NRDA an extensive study of lake trout reproduction found that lake trout could no longer reproduce. But a thorough investigation revealed that PCBs long thought to be the primary factor appear to be less important than egg thiamin deÆciency. This is believed to happen because lake trout eat alewife a Æsh that was introduced into the Great Lakes. As a result lake trout injuries will not be included in the NRDA.1 Unique economics NRDAs are unique in terms of their economic aspects especially in the role of compensatory damages. Compensatory damages seek to compensate the public for the loss of a resource from the time when the damage occurred until restoration. In the past these damages were valued in monetary terms but the new emphasis on restoration now favors habitat equivalency.5 In habitat equivalency the object is to Ænd one aspect of a habitat called a metric that can stand for the habitat as a whole.This metric is then used to assess other habitats and to Ænd comparable replacements. For example in a coastal setting trustees might use the average 51N J. Environ. Monit. 2000 2 US Focus Fox River Aerial photograph of the lower Fox River adjacent to the Fort James East Paper Mill (the facility is in the foreground). PCBs used in the manufacture of carbonless copy paper led to the Fox River's contamination. Photograph courtesy US Fish and Wildlife Service. stem density and height of sea grass to compare habitats.This one measure can account for Æsh habitat sediment stabilization contaminant Æltration and all of the other services the habitat provides. In addition to determining whether a given area has the physical and biological capacity to provide a range of services. NRDA economists also look at 52N J. Environ. Monit. 2000 2 ``opportunity'' and ``payoff''. For example to use the capacity of a wetland to Ælter water there needs to be an upstream pollution source to present the opportunity. If there were a shellÆsh bed downstream then the payoff is great while the presence of a fast Øowing stream would offer a smaller payoff. In the next few years the giant NRDAs for the Fox and Hudson Rivers will sorely test these concepts in an effort to see if the legal system can use science and economics to get back to the future.Notes 1 US Fish and Wildlife Service press release (http //www.fws.gov/r3pao/ext_affr/ news_rel/ea99_50.html) 2 Superfund status of selected federal Natural Resource Damage SettlementsGAO/RCED-97-10 November 1996. 3 Phase II Reassessment Data Evaluation and Interpretation Report for the Hudson River PCB Superfund Site; U.S. Environmental Protection Agency(Region 2) U.S. Government Printing OfÆce Washington DC February 1997.Available at http // www.epa.gov/region02/superfnd/hudson/ 4 Phase II Reassessment Low-Resolution Coring Report for the Hudson River PCB Superfund Site; U.S. Environmental Protection Agency (Region 2) U.S. Government Printing OfÆce Washington DC July 1997. Available at http //www.epa.gov/region02/superfnd/ hudson/ 5 National Oceanic and Atmospheric Administration Damage Assessment and Restoration Program (revised June 1996) Habitat Equivalency Analysis. Policy and Technical Paper Series No. 95-1. Rebecca Renner Science Writer and Editor Tel z1 570 321 8640 Fax z1 570 321 9028 E-mail applepie@sunlink.net

ISSN:0960-7919    

DOI:10.1039/b003624m

出版商:RSC    

年代:2000

数据来源: RSC

摘要:

Pesticides in Perspective Introduction The Ærst article in this series (JEM 2000 2(2) 34N) reported the results of government policies and regulations for the monitoring of pesticide residues in food. These help to ensure that no pesticide residues exist at concentrations above the accepted set limits and therefore indicates that users comply with supplied instructions on how much how often and on what crops the pesticide can be used. The present article takes a step back in the registration process and reviews the human health Does the mere presence of a pesticide residue in food indicate a risk?{ Pesticides are chemicals both man made (synthetic) and naturally occurring that control the diseases insects and weeds which harm or destroy our food.The man made ones can be thought of as ``medicines for plants'' which are only needed when those naturally occurring made by the plant do not work well enough. It is not always realised that a plant's response to attack is to produce phytotoxins–their own in-built pesticides. In reality 99.99% of all pesticides are found naturally in plants. Only 0.01% are man made. It has been estimated that 30±40% of the worlds food crops are destroyed annually by a combination of insects plant pathogens weeds etc. In the US it is estimated that 37% of all crops are lost each year despite the use of pesticides and other forms of crop protection. Today pesticides not only play a major role in producing food quantity but also contribute to high quality.The key beneÆts of pesticide use on crops are:- . Sustainable food supply . Positive health beneÆts from regu- {The opinions expressed in the following article are entirely those of the authors and do not necessarily represent the views of either The Royal Society of Chemistry the Editor or Editorial Board of JEM Zeneca Agrochemicals or those of the Column Editor. This journal is # The Royal Society of Chemistry 2000 risk assessments that have to be conducted in relation to the consumer by pesticide companies and government regulators before a pesticide can be approved for use. Naresh Atreya has MSc. in analytical chemistry and a Law degree (LLB Hons) from London University UK. Naresh has worked for Zeneca Agrochemicals at Jealott¡s Hill Research Station Bracknell UK for nearly 30 years the majority of which has been in the pesticide residue and dietary exposure consumer risk assessment area.He is a Senior Residue Chemist larly eating good healthy fruit and vegetables . Environmental and socio-economic aspects . Habitat protection Furthermore in the light of the estimates for continued world population growth and the recognition that the worlds remaining natural ecosystems should be protected in the face of competition from development for housing and cultivation for food production pesticides will remain essential for the foreseeable future. The presence of pesticide residues in food in relation to human health is subject to great debate between the agrochemical industry the scientiÆc community government regulators and consumers.The development and subsequent proliferation of pesticides since 1940's has had a profound social impact in a number of ways. High quality fresh vegetables are the showcase of every modern supermarket entrance. Today's consumer expects a constant year-round supply of clean healthy and above all safe produce. Pesticides have been a key component in fulÆlling these demands at lower cost in real terms than ever before. The safety of the food we eat is of paramount importance to us all. Unfortunately the public perception Pesticides and has recently taken on a new role as a Food Advocate for Zeneca Agrochemicals.Naresh has also been consultant to organisations such as the Food and Agricultural Organisation (FAO) and United Nations Industrial Development Organisation (UNIDO) and has been involved in many training courses in a number of countries. Dr Terry Clarke Column Editor Zeneca Agrochemicals E-mail Terry.Clarke@aguk.zeneca.com and conÆdence in the safety of their food has been seriously undermined in recent years. Their experience with the food industry over E. coli salmonella listeria BSE and dioxins have led to the belief that government scientists and the industry are ``sparing'' with the facts. Scares in the past such as the use of Alar on apples together with the more recent issue of organophosphates on carrots have fuelled consumers concerns on dangers of treating crops with pesticides.This has lead to a common misconception that crops are routinely treated with pesticides and that unseen residues are on everything we eat. These negative impressions have ensured that pesticides enter the realms of politics. The beneÆts of pesticides in terms of sustainable food supply health environment and socioeconomic aspects are hardly debated in the public. The purpose of this paper is to put pesticide residues in food into perspective by outlining the risk assessment required by regulators before pesticides can be sold. This methodology ensures that the consumer is not exposed to any real risk from the use of pesticides. Any potential risk arising from residues in food is fully evaluated by the industry and independently assessed by government scientists.53N J. Environ. Monit. 2000 2 Pesticides Concerns about consumer exposure A major concern is the potential risk to the health of consumers that pesticides residues on food may pose. When pesticides are used to protect crops during growth or during storage after harvest minute traces of the pesticide or its breakdown products (metabolites) may remain on the crop. These are known as pesticide residues. The simple fact that pesticides are designed to be toxic to pests means that there is also a potential risk to people. The risk perceptions of the public are inØuenced by the way individuals view the world and their attitude is heavily inØuenced by the ability of the individual to control the risk.If people underestimate personal risks they may not take appropriate steps to reduce their exposure to the hazards. For example individuals believe that they can control their intake of alcohol or fat so that they are regarded to be acceptable risks. However pesticides residues are outside their control and are therefore perceived as high risk. Principles of dietary exposure risk assessment With regards to human health the safety of pesticides is measured by assessing the risk which is determined by the two components exposure and hazard. In order to measure the exposure we need to know two things:- (a) Amount and type of food we eat.The estimate of the amount and type of food we eat is taken from the tables of standard diets published by national governments. Food surveys show how much of a particular food is consumed in grams per day by adults children and infants. Increasingly dietary information is being compiled on specialised groups such as vegetarians and ethnic groups who may consume more of a particular type of food. The Ægures are arrived at by conducting food surveys which include extremes of consumption patterns. This means that exposure is taken to be ``worse case''. (b) Amount of pesticide residues in food. There are established guidelines for assessing pesticide residues in food before approving its use. These studies are conducted under Æeld glass house and crop storage conditions are governed by international accepted guidelines and are conducted under a 54N J.Environ. Monit. 2000 2 variety of environmental conditions. The output from these studies provide data which is used to calculate the following information on the residues in food. . Maximum residue level (MRL) used for setting legal limits for trading produce. This is also known as tolerance in the USA. . Average or median residue levels used for assessment of long term exposure. . Highest residue levels used for assessment of short term exposure. The hazard potential of any pesticide is determined by its mammalian toxicity or its ability to cause harm to humans. These tests are complex extensive and time consuming hence costly and include feeding rodents with a diet containing the pesticide at different doses for their lifetime.From these results the following information is obtained:- . the type of harm that may be caused at high exposure level to a pesticide . the level of exposure that is safe and causes no harm and this is deÆned as the No observed adverse effect level (NOAEL). What is safe exposure to humans? It is assumed that humans are 10 times more sensitive than the experimental animals. It is also assumed that some humans are 10 times more sensitive than others. To accommodate this a safety factor of at least 100 fold is applied to the lowest experimental NOAEL to determine the maximum permissible exposure to humans.This is called the acceptable daily intake (ADI). For example if the lowest safe level for an experimental animal is 0.1 mg kg21 body weight per day then a large safety margin of 100 fold ensures that 0.001 mg kg21 body weight per day is safe for humans. An ADI is:- the amount of chemical which can be consumed everyday of an individuals entire lifetime in the practical certainty on the basis of all known facts that no harm will result. From toxicity studies both long term (ADI) and short term (acute) reference doses (RfD) for a particular pesticide are established. These values are Æxed for a particular pesticide. These permissible exposure values to humans are compared with estimates of dietary exposure based on actual residue levels and quantity of food consumption to determine whether exposure is within acceptable limits.If any potential exposure and risk to consumers from residues in food is estimated to be above acceptable levels (ADI) risk management measures to reduce that exposure are taken by the manufacturer and regulatory authorities. Dietary exposure consumer risk assessment methodology (Europe and WHO) The estimation of long term exposure (chronic) The World Health Organisation (WHO) 1989 publication ``Guidelines for predicting the dietary intake of pesticide residues'' has formed the basis of national and international consumer risk assessments of pesticide residues for a number of years.However it was recognised that this tiered approach was too prescriptive with the TMDI (theoretical maximum daily intakes) being a crude overestimate. The TMDI calculation is based on an average consumption of each food for which an MRL exists and is multiplied by the MRL value to estimate the contribution from each food. The total of all the contributions is taken to be the TMDI. The TMDI used to be further reÆned but these reÆnements were also too prescriptive and therefore recently a more reÆned intake calculation is provided by the international estimated daily intake (IEDI) and the national estimated daily intake (NEDI). The IEDI or NEDI are intended to be more accurate estimates which should reØect real diets and real residue levels.In other words this would allow a greater Øexibility of using a number of ``factors'' in a best estimate of dietary intake. If the IEDI or NEDI exceeds the ADI then risk management action may be required such as integrated crop management. This generally results in reduction in the level of residues in various crops. Important changes from previous guidelines The use of supervised trials median residues (STMR). The new concept of STMR was introduced rather than maximum residue levels (MRL). It was considered that the STMR is the most likely residue to be encountered by consumers as a result of usage of the pesticide at the critical good agricultural practice (maximum rates and shortest harvest intervals).Whilst the use of median or arithmetic mean generally give similar results the use of median was preferred because it avoids certain calculation problems when some of the residues were less than the limit of quantiÆcation (LOQ). STMRs will usually still overestimate the residues found in practice since residue data are produced under a worst label use with respect to rates and harvest intervals and other factors such as household cooking and processed produce are not taken into account. Effects on residue levels due to storage processing or cooking practice. Many raw crop commodities such as wheat and potatoes are not eaten directly by the consumer. They are either cooked or processed into bread or breakfast cereals for example and these products are then consumed.Pesticide residues are generally signiÆcantly reduced in processed food. Processing studies allow a better estimate of residues to which consumers are ultimately exposed. However in a few cases residues may be concentrated in the processed commodity for example drying grapes into raisins. The situation once identiÆed can then be assessed against the daily consumption of raisins. Population sub-groups. In the UK food consumption data for adults children toddlers and infants are now used routinely used for risk assessments. This will be extended to vegetarians in the future. In practice the number of population sub-groups will be limited by the availability of reliable consumption data.This compares to methods used by other EU member states such as Germany where `extreme' consumers (4 year old child or 30-40 year old adult female) are used and the Netherlands where an average adult consumer are only considered. Consumption data for some WHO countries is not readily available which makes this type of risk assessment difÆcult. Short term (acute) exposure Variability of pesticide residues from item to item of a food. The need to estimate short term exposure was identiÆed in the UK as a consequence of results indicating the variability in residue levels from item to item of a food e.g. apples. MRLs are based on composite samples in which a number of commodity units are bulked and analysis carried out on the mixed sample.Recent UK studies have indicated that item to item variation of a food within these composite samples is higher than had been previously assumed. The occasional high residue leading to short-term dietary intake above the ADI for a day or so was generally considered acceptable. However for pesticides that have acute toxic effects the maximum amount likely to be consumed during a short time must also be considered. For acute risk assessment we need the following :- . the highest residue level measured in an individual commodity (for example an individual apple); . the number of items which may be consumed in a single meal; . `hazard' is represented by the ``acute reference dose'' (acuteRfD) e.g.the level that will not cause harm following a single exposure. Probabilistic approach to the estimation of acute exposure assessment. The probabilistic modelling approach to acute dietary exposure has been developed. The simulation models can be used with different inputs values with the objective of achieving a complete representation of all possible outcomes that might occur. These simulation techniques use algorithms to randomly sample the probability distribution functions of the input parameters. The traditional sampling technique Monte Carlo takes values at random from the entire range of probability distribution for each of its input parameters in the model. These are then used to calculate the output values. The process is then repeated for the next iteration and so a distribution of the output parameters can be built up.By using such simulation techniques different permutations of consumption and residue level can be taken into account and probability distributions can be calculated which give both the likelihood and the magnitude of dietary exposure levels. The consumption of food the residue levels of pesticides in food and individual body weights can all be represented by probability distributions. The probabilistic approach is the best methodology for intake estimates but detailed consumption and residue data required for such an approach is not yet available in Europe as a whole or some EU member states. As a consequence short term dietary exposure assessments based on probabilistic methodology are Pesticides not yet accepted at the international level although widely used in the USA.Alternative approaches to the estimation of acute exposure. As stated above it may not always be possible to use probabilistic methods on a routine basis due to the detailed requirements and the resources required. The nonprobabilistic approaches to the estimation of acute intake are known as deterministic methods. These methods usually overestimate exposure in order to protect high-level consumers. Deterministic methods rely on Æxed point estimates of residue data food consumption and body weights. They do not take variability into account and tend to use conservative estimates to protect high-level consumers.However probabilistic methods take into account real variability in residue data food consumption and body weights and provide an estimate of the likely level of exposure. It does not use conservative defaults to protect high-level consumers and has the ability to combine potential exposure from multiple sources. Dietary exposure consumer risk assessment methodology (USA) Essentially both long term and short term dietary exposure assessment requirements are similar to those described under Europe and WHO. Assessment requires toxicology end points such as ADI for chronic and acute reference dose for acute exposure which will be obtained from studies conducted according to international guidelines.Dietary exposure estimation would require food consumption data for all sub-population of the US (in total 29 sub-populations) and residue levels in food from studies conducted in US. However there are some fundamental differences which arose due to the introduction of the food quality protection act (FQPA) which was signed into US law on August 3,1996. FQPA requires that EPA (Environment Protection Agency) establish a tolerance (equivalent to MRL in Europe) which is considered to be safe and the major components of FQPA are described below:- . Additional protection for children and infants Standard safety factor of 100 as used in Europe and the rest of the world but on top of this up to an additional 106 safety factor for children and infants.55N J. Environ. Monit. 2000 2 Pesticides Table 1 Dietary exposure risk assessment EU Chronic Risk Analysis NEDI is used Tier 1. Assumes all residues are at the MRL and 100% of the crop is treated Tier 2. STMR or residues in edible portion Tier 3. Further reÆnements e.g. processing Tier 4. Monitoring and total diet data Acute Risk Analysis Tier 1. MRL and 100% crop treated Tier 2. Incorporating processing etc. Tier 3. Probabilistic modelling of residue data Tier 4. Probabilistic modelling of residue data from market basket Key Issues Current approach for chronic analysis is too prescriptive For acute assessment residue variability i.e. unit to unit variation may be required. .Aggregate assessment of risk Single pesticide Total exposure from all sources of non-occupational exposure (dietaryzdrinking waterzresidential exposure) . Cumulative risk Multiple compounds Total exposure from all sources of non-occupational exposure (dietaryzdrinking waterzresidential exposure) Probabilistic approaches are well developed in the USA as compared to Europe and these are routinely used for short term dietary exposure assessments. This is because comprehensive food consumption information is available for up to 29 sub-population groups which is essential for probabilistic modelling. Currently the dietary exposure evaluation model (DEEM) is used for both chronic and acute risk assessment and incorporates probabilistic modelling for acute dietary exposure calculations for all 29 sub-group populations.A comparison of dietary exposure risk assessment methodologies in the European Union and USA are given in Table 1. Conclusions It is no exaggeration to say that pesticides are among the most highly 56N J. Environ. Monit. 2000 2 USA Tier 1. Assumes all residues are at the maximum tolerance and 100% of the crop is treated Tier 2. Average residues used and % of crop treated factored Tier 3. Residue data from established monitoring programs used. Tier 4. Market basket surveys Tier 1. Assumes all residues are at the maximum tolerance and 100% of crop treated. Tier 2. Maximum residues from supervised trials 100% of crop treated.Tier 3. Probabilistic modelling of residue data Tier 4. Probabilistic modelling from market basket surveys. Cumulative exposure from all chemicals having a common mechanism of toxicity Additional 106 safety factor for children Acute exposure based on 99.9 percentile regulated of all man-made chemicals their testing and regulation being equivalent to that of pharmaceuticals. Manufacturers generate a large volume of information to be able to register a pesticide for sale. They have to demonstrate wide margins of safety before approval of a pesticide is granted by governments. These risk assessments are conducted by the manufacturer of the pesticide and independently by the regulatory authority who will decide whether or not to approve the pesticide.National government monitoring programmes indicate that we only consume a fraction of what has been deemed to be safe. It is clear that industry and government take human safety and monitoring of pesticide residues very seriously. The fact that occasional high residues are detected conÆrms that surveillance schemes are working in the interest of the consumer. It is important to understand that MRLs are trading legal limits and they enable government regulators to check that pesticides are being used for crop protection correctly. MRLs are not health standards and even if occasional exceedance occurs it is highly unlikely that consumers are put at risk. The development of important new methodologies for the estimation of dietary exposure and subsequent risk assessment should improve the accuracy of dietary intake estimates and ensure that more realistic estimates are derived using all the available data. The residue variability in a single food item together with new acute exposure methodology particularly probabilistic approaches will reassure consumers about acute toxic pesticides. The Joint Meeting on Pesticide Residues (JMPR) have already implemented chronic dietary exposure into their work. The UK regulations now include both chronic and deterministic acute exposure risk assessments. It is important to understand that these deterministic acute exposure risk assessments still signiÆcantly overestimate dietary intake. In the USA FQPA uses probabilistic modelling which ensures that there is no potential risk from pesticide residues in food consumed by all sub-population groups. It is hoped a harmonised EU/international approach to consumer dietary exposure and risk assessment can be agreed soon particularly with respect to probabilistic modelling. Pesticides play an important role in delivering the beneÆts of cheaper better quality safe food that is available all year round. In my opinion pesticide residues pose a minimal risk to the consumer. Dr Naresh Atreya Zeneca Agrochemicals

ISSN:0960-7919    

DOI:10.1039/b003623o

出版商:RSC    

年代:2000

数据来源: RSC