摘要:

Brominated dibenzo-p-dioxins and dibenzofurans can be formed under laboratory conditions by pyrolysis of flame retardants based on polybrominated biphenyls and biphenyl ethers. Their occurrence in the environment, however, is due to combustion processes such as municipal waste incineration and internal combustion engines. As these processes generally take place in the presence of an excess of chlorine, predominantly mixed brominated and chlorinated compounds have been identified so far in environmental samples. Brominated dibenzo-p-dioxins or dibenzofurans bind to the cytosolic Ah receptor about as avidly as their chlorinated congeners and induce hepatic microsomal enzymes with comparable potency. The same holds true for mixed brominated-chlorinated compounds. Gross pathologic symptoms-hypothyroidism, thymic atrophy, wasting of body mass, lethality-also occur at doses that, on a molar concentration basis, are virtually identicalto those seen with the chlorinated compounds. Their potency to induce malformations in mice following prenatal exposure is equivalent to that of chlorinated dibenzo-p-dioxins and dibenzofurans. Possible activities as (co)carcinogens and endocrine disrupters have not been evaluated, but are likely to exist. Considering the overall similarity in action of chlorinated and brominated dibenzo-p-dioxins and dibenzofurans, environmental and health assessments should be based on molar body burdens without discrimination for the nature of the halogen.

ISSN:0098-4108    

DOI:10.1080/009841097160456

出版商:Informa UK Ltd    

年代:1997

数据来源: Taylor

摘要:

In recent years, several regulatory agencies and professional societies have recommended an occupational exposure limit (OEL) for formaldehyde. This article presents the findings of a panel of experts, the Industrial Health Foundation panel, who were charged to identify an OEL that would prevent irritation. To accomplish this task, they critiqued approximately 150 scientific articles. Unlike many other chemicals, a large amount of data is available upon which to base a concentration-response relationship for human irritation. A matheReceived matical model developed by Kane et al. (1979) for predicting safe levels of exposure to irritants based on animal data was also evaluated. The panel concluded that for most persons, eye irritation clearly due to formaldehyde does not occur until at least 1.0 ppm. Information from controlled studies involving volunteers indicated that moderate to severe eye, nose, and throat irritation does not occur for most persons until airborne concentrations exceed 2.0-3.0 ppm. The data indicated that below 1.0 ppm, if irritation occurs in some persons, the effects rapidly subside due to "accommodation." Based on the weight of evidence from published studies, the panel found that persons exposed to 0.3 ppm for 4-6 h in chamber studies generally reported eye irritation at a rate no different than that observed when persons were exposed to clean air. It was noted that at a concentration of 0.5 ppm (8-h TWA) eye irritation was not observed in the majority of workers (about 80%). Consequently, the panel recommended an OELof 0.3 ppm as an 8-h time-weighted average (TWA) with a ceiling value (CV) of 1.0 ppm (a concentration not to be exceeded) to avoid irritation. The panel believes that the ACGIH TLV of 0.3 ppm as a ceiling value was unnecessarily restrictive and that this value may have been based on the TLV Committee's interpretation of the significance of studies involving self-reported responses at concentrations less than 0.5 ppm. The panel concluded that any occupational or environmental guideline for formaldehyde should be based primarily on controlled studies in humans, since nearly all other studies are compromised by the presence of other contaminants. The panel also concluded that if concentrations of formaldehyde are kept below 0.1 ppm in the indoor environment (where exposures might occur 24 h/d) this should prevent irritation in virtually all persons. The panel could not identify a group of persons who were hypersensitive, nor was there evidence that anyone could be sensitized (develop an allergy) following inhalation exposure to formaldehyde. The panel concluded that there was sufficient evidence to show that persons with asthma respond no differently than healthy individuals following exposure to concentrations up to 3.0 ppm. Although cancer risk was not a topic that received exhaustive evaluation, the panel agreed with other scientific groups who have concluded that the cancer risk of formaldehyde is negligible at airborne concentrations that do not produce chronic irritation.

ISSN:0098-4108    

DOI:10.1080/009841097160465

出版商:Informa UK Ltd    

年代:1997

数据来源: Taylor

摘要:

An ecologic study design was used to investigate the relationship between cancer risks and residence in communities adjacent to petrochemical industrial counties (PICs). Directly age-adjusted mortality rates for cancer during 1982-1991 among 16 counties characterized by a heavy concentration of petrochemical industries were compared to rates among 16 matched counties with similar concentration of nonpetrochemical manufacturing industries, urbanization level, and demographic characteristics. An excess rate for liver cancer among males was found in the so-called PICs. The correlation could not be explained by confounding variables such as urbanization, socioeconomic class, or employment in nonpetrochemical industries. No other increased cancer risks were found to be associated with residence near petrochemical industries.

ISSN:0098-4108    

DOI:10.1080/009841097160474

出版商:Informa UK Ltd    

年代:1997

数据来源: Taylor

摘要:

Fusaric acid (FA) is produced by several Fusarium species that commonly infect cereal grains and other agricultural commodities. FA in the feed of nursing dams is lactationally transferred to the suckling offspring and alters serotonin (5-hydroxytryptamine, 5HT) in the pineal gland of the neonate rat. 5HT is involved in melatonin (MEL) production by the pineal gland. MEL is a hormone important in reproduction and seasonality in animals. Therefore, the effects of FA on MEL in the serum and pineal gland of male and female 21-d-old weanling rats from dams on an FA diet were studied. MEL was measured by enzyme-linked immunosorbent assay (ELISA), which was standardized for directly measuring MEL in rat serum and pineal homogenates. At 200 ppm in the diet of nursing dams, FA increased serum MEL in both sexes. Results obtained from ELISA were supported by high-performance liquid chromatography (HPLC) analysis with fluorescence detection. MEL analysis of the pineal gland homogenates by ELISA and HPLC supported observations in the serum. Analogously, in pineal cell monolayer cultures, FA at 1 M and 100 M concentrations increased MEL in a dose-dependent manner as compared to the control cells. This is the first report that FA increases MEL in vivo and in vitro and suggests that FA contamination of diets may affect mechanisms involving MEL synthesis.

ISSN:0098-4108    

DOI:10.1080/009841097160483

出版商:Informa UK Ltd    

年代:1997

数据来源: Taylor

摘要:

Identification of constituents responsible for the pulmonary toxicity of fugitive combustion emission source particles may provide insight into the adverse health effects associated with exposure to these particles as well as ambient air particulate pollution. Herein, we describe results of studies conducted to identify constituents responsible for the acute lung injury induced by residual oil fly ash (ROFA) and to assess physical-chemical factors that influence the pulmonary toxicity of these constituents. Biochemical and cellular analyses performed on bronchoalveolar lavage fluid obtained from rats following intratracheal instillation of ROFA suspension demonstrated the presence of severe inflammation, an indicator of pulmonary injury, which included recruitment of neutrophils, eosinophils, and monocytes into the airway. A leachate prepared from ROFA, containing predominantly Fe, Ni, V, Ca, Mg, and sulfate, produced similar lung injury to that induced by ROFA suspension. Depletion of Fe, Ni, and V from the ROFA leachate abrogated its pulmonary toxicity. Correspondingly, minimal lung injury was observed in animals exposed to saline-washed ROFA particles. A surrogate transition metal sulfate solution containing Fe, V, and Ni largely reproduced the lung injury induced by ROFA. Metal interactions and pH were found to influence the severity and kinetics of lung injury induced by ROFA and soluble transition metals. These findings provide direct evidence for the role of soluble transition metals in the pulmonary injury induced by the combustion emission source particulate, ROFA.

ISSN:0098-4108    

DOI:10.1080/009841097160492

出版商:Informa UK Ltd    

年代:1997

数据来源: Taylor