摘要:

Significant developments have been made at the international level in the methodology for conducting dietary risk assessments. The existing chronic exposure assessment methodology has been updated so that it takes account of the level of residues to which consumers are most likely to be exposed. In addition, short-term exposure assessment methodology has also been developed. This uses portion size data and takes account of the variability in residue levels between individual units where this is appropriate to the way the commodity is consumed. Other refinements to the assessment can also be made. Although the short-term methodology has been used successfully by a number of regulatory authorities, there is a need for data on portion sizes and typical unit weights before it can be fully implemented internationally.

ISSN:0265-203X    

DOI:10.1080/026520300412456

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Risk assessment for pesticide residues in food has previously concentrated on chronic intake, probably with the assumption that if the chronic intake is acceptable, acute intake will also be acceptable. Data generation is expensive so we should extract, where possible, information useful for acute intake estimation from supervised residue trials. Residues in individual units of fruit or vegetables are more variable than the residues in composite samples and the distribution in individual units is probably best approximated by a lognormal distribution, but further evidence is needed. Theory provides a method for calculating the variability of replicate composite samples and applying it to individual units. The expected residue in the 95th or 99th percentile single fruits may then be calculated. An example for folpet residues in apples showed that the 95th and 99th percentile apples would contain 1.8 × and 2.3 × the residue in the composite sample, respectively. For abamectin in apples the 95th and 99th percentile factors were 6.7 and 15, respectively. The 95th and 99th percentile factors for azinphos-methyl in apples, based on single apple analysis, were 1.7 and 2.1, respectively.

ISSN:0265-203X    

DOI:10.1080/026520300412465

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The US Environmental Protection Agency (EPA) assesses acute dietary exposure to pesticide residues using a tiered approach, proceeding from conservative to more refined assumptions as the risk management situation requires. Toxicity and food residue data used by EPA in assessing acute dietary risk are obtained from studies submitted by chemical companies in support of pesticide registration and tolerance setting. The primary source of food consumption data used by EPA in acute dietary risk assessments is the Continuing Survey of Food Intakes by Individuals (CSFII) 1989–1991.

ISSN:0265-203X    

DOI:10.1080/026520300412474

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Consumption data can be expressed in different ways although it should be comparable to what is known about the toxicological property of the chemical in question and the likely pattern of consumer exposure. For example if the chemical has an acute toxic effect the consumption data should ideally be based on a single eating occasion or consumption over a single day and be based on the population of concern. This paper describes five UK dietary surveys and consumption data, specifically relevant to acute exposure assessment, from adult and pre-schoolchildren surveys. The acute consumption data are taken from the first day of the dietary regime. Closer examination of the dietary survey information suggests that either picking a random survey day or selecting all consuming days give 97.5 percentile values which are not significantly different. Consumption data are given for whole commodities and a few fruit juices. Examination of the dietary survey information shows that the consumption patterns are very different between whole commodities (e.g. apples), ingredients (e.g. apple in a dish or recipe) and juices and between adults and young children.

ISSN:0265-203X    

DOI:10.1080/026520300412483

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Within the context of the current UK policy for those commodities where the potential variability of residues in individual commodity units is taken into account, a variability factor nu, which reflects the ratio of a high level residue in the individual commodity unit to the corresponding composite residue level, is used. Data gathered from supervised industry trials in which individual items were analysed following treatment, although limited, show that variability is typically lower than that reflected by the default factors currently used and that the range of variability is reproducible over the limited range of different a.i./crop/method of application combinations investigated. In order to improve the accuracy of the acute dietary exposure estimate, the European Crop Protection Association (ECPA) proposes the following alternative to the current Tier I approach. The residue level input from a ‘hot’ unit within the dietary risk assessment should be determined using the highest composite sample residue from supervised field trials and a generic variability factor (nu) determined experimentally from supervised trials. The variability factor itself should be calculated as the 95th percentile level of the residue level found in an individual unit (or single serving portion for large crops) divided by sample mean for data produced from supervised trials. This would improve the accuracy of the Tier I approach and allow attention to be focused on particular a.i./crop/method of application combinations where the NESTI> acute RƒD (based on a Tier I assessment) and generation of individual unit residue data for the particular outlet or other mitigation may be appropriate.

ISSN:0265-203X    

DOI:10.1080/026520300412492

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Probabilistic modelling techniques allow much more realistic estimates of exposure and risk by computing the use of the full range of potential exposures rather than single ‘worst case’ exposures. However, these techniques require additional considerations regarding the appropriate data and models. This article reviews the theoretical aspects of probabilistic modelling and also considers some of the practical applications. The most common method, called Monte Carlo analysis, is discussed in some detail. The practical application of Monte Carlo to risk assessments is presented along with an evaluation of the input parameters. Topics also discussed include considerations of the requirements for precision and procedures for validation of assessments.

ISSN:0265-203X    

DOI:10.1080/026520300412500

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In 1996, studies on a range of organophosphate and carbamate pesticide residues in fruit that may be eaten as single items reported variability. The usual point estimate exposure model did not take account of the variation in residue levels between items or variation in consumption patterns of individual consumers. Using only the highest residue levels and consumption values for each of the multiple sources (different fruit) could lead to overestimates of residue intakes which would indicate higher than actual levels of risk. Probabilistic simulation was identified as a tool that could utilize all the available information from the variability studies and fruit consumption data collected from dietary surveys. The estimation of exposure of toddlers to carbaryl is shown as an example. The number of samples representing some combinations of fruit in the toddler dietary survey was particularly low and the validity of extrapolating from these was unknown. Therefore, consumption values were simulated using the data for frequency and amount eaten from the whole database. The data indicated that there were some weak positive associations between consumption levels of the different fruit. However, inclusion of correlated sampling in the model simulation was considered too conservative. The profiles of carbaryl residues in different retail batches differed. Therefore a model was constructed that differentiated between different residue profiles and sampled separate residue levels for each item assumed to be eaten. Two simpler models, both ignoring the effect of re-sampling from the same batch, were also used to estimate exposure. All three models were considered to give realistic views of the likely short-term intakes and the outputs were useful as an aid to decision-making in terms of necessary regulatory action.

ISSN:0265-203X    

DOI:10.1080/026520300412519

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

To perform risk assessments for short term dietary intakes of pesticides it is necessary to determine an acceptable level of exposure from the available toxicity studies. This type of assessment is a relatively new development in regulatory toxicology and often the studies currently available are not optimal for such uses. The strengths and weaknesses of currently performed study types are presented. Consideration of the entire toxicity data base is essential.

ISSN:0265-203X    

DOI:10.1080/026520300412528

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The approach of the Joint Meeting on Pesticide Residues to the establishment of the acute reference dose for pesticides is presented and related issues are discussed. Three main points seem relevant when discussing the acute reference dose: (1) what compounds should have an acute reference dose, (2) what toxicological database is required for the establishment of an acute reference dose; (3) what safety factors are to be used. It is concluded that (1) groups of compounds that need an acute reference dose can be identified, whereas general rules for identifying groups not requiring an acute reference dose cannot be easily given; (2) studies from the standard toxicological database can often be used to allocate an acute reference dose and the usefulness of refinements (by requesting specific studies) should be evaluated after intake assessment; general rules on study requirements cannot be easily given; (3) more thought should be given to what safety factors apply in certain circumstances.

ISSN:0265-203X    

DOI:10.1080/026520300412537

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Reference doses (RƒD) for the definition of tolerable food residues have traditionally been based on the lowest no observed adverse effect level (NOAEL), which usually comes from chronic toxicity studies. While this is generally agreed to be a safe approach to evaluate the overall significance of expected consumption it is clear that it is not appropriate for evaluation of the toxicological significance of residues in a single meal. Standard acute toxicity tests are not designed to generate an NOAEL, from which an RƒD can be derived. They are more appropriate to evaluating risk following accidental high exposure to the product itself rather than to food residues. A typical toxicological database for a pesticide active substance contains studies which may be appropriate, on a case-by-case basis, to evaluate shorter term endpoints of interest for specific molecules, such as developmental or acute neurotoxicity studies. However, their specificity limits their scope of application. General toxicological endpoints are well covered by short-term, 28- or 90-day, guideline studies. However, neither of these studies is ideal for setting of an acute RƒD (ARƒD) as the treatment period is significantly longer than the duration of consumer exposure. This could be balanced by applying a reduced safety factor to the NOAEL to set the ARƒD. Alternatively, a test guideline could be designed to generate a relevant acute NOAEL but the time necessary for development, validation and acceptance of such a guideline means that an interim approach is, in any case, necessary.

ISSN:0265-203X    

DOI:10.1080/026520300412546

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor