Methodologies for derivation, listing of available values, and adjustments to allow for early lif... more Methodologies for derivation, listing of available values, and adjustments to allow for early life stage exposures.
trestle were engulfed in flame. The trestle, largely constructed of creosote-treated wood ties an... more trestle were engulfed in flame. The trestle, largely constructed of creosote-treated wood ties and structural beams, continued to burn uncontained for 48 hours. Smoke from the fire was most intense during the first two days of the event. Initially, a large column of black smoke rose directly from the site in a vertical plume, flattening out at 1400-2000 feet elevation (see pictures, Appendix A). Predominant weather conditions throughout most of the fire allowed the thick black smoke to disperse high in the atmosphere, reducing exposures in the Sacramento area. Late Friday night and into Saturday morning, however, portions of Sacramento, Yolo, and Sutter counties were impacted with smoke as the weather and wind conditions changed. Particulate matter concentrations rose dramatically at one air monitoring location to levels considered unhealthy for sensitive groups. Fortunately, the worst air quality readings measured at this site lasted only a matter of hours before clearing. Particul...
... and Dr Martyn T. Smith (School of Public Health, University of California, Berkeley) for cons... more ... and Dr Martyn T. Smith (School of Public Health, University of California, Berkeley) for constructive discussions on aspects of urethane metabolism and carcinogenesis. They also thank Anita Vallejo and Mary King for secretarial assistance. Andrew G. Salmon Lauren Zeise ...
The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588, Connelly) was enact... more The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588, Connelly) was enacted in September 1987. Under this Act, stationary sources of air pollution are required to report the types and quantities of certain substances their facilities routinely release into the air. The goals of the Air Toxics "Hot Spots" Act are to collect emission data, identify facilities having localized impacts, ascertain health risks posed by those facilities, notify nearby residents of significant risks and reduce emissions from significant sources. The Technical Support Document for Cancer Potency Factors (TSD) contains cancer unit risks and potency factors for 107 of the 201 carcinogenic substances or groups of substances for which emissions must be quantified in the Air Toxics Hot Spots program. These unit risks are used in the cancer risk assessment of facility emissions. The purposes of this revision to the TSD is to provide updated calculation procedures used to derive t...
Research on disease causation often attempts to isolate the effects of individual factors, includ... more Research on disease causation often attempts to isolate the effects of individual factors, including individual genes or environmental factors. This reductionist approach has generated many discoveries, but misses important interactive and cumulative effects that may help explain the broad range of variability in disease occurrence observed across studies and individuals. A disease rarely results from a single factor, and instead results from a broader combination of factors, characterized here as intrinsic (I) and extrinsic (E) factors. Intrinsic vulnerability or resilience emanates from a variety of both fixed and shifting biological factors including genetic traits, while extrinsic factors comprise all biologically-relevant external stressors encountered across the lifespan. The I×E concept incorporates the multi-factorial and dynamic nature of health and disease and provides a unified, conceptual basis for integrating results from multiple areas of research, including genomics, ...
Journal of Toxicology and Environmental Health Part a, Dec 20, 2007
Substantial effort has been invested in improving children&am... more Substantial effort has been invested in improving children's health risk assessment in recent years. However, the body of scientific evidence in support of children's health assessment is constantly advancing, indicating the need for continual updating of risk assessment methods. Children's inhalation dosimetry and child-specific adverse health effects are of particular concern for risk assessment. When focusing on this topic within children's health, key issues for consideration include (1) epidemiological evidence of adverse effects following children's exposure to air pollution, (2) ontogeny of the lungs and effects on dosimetry, (3) estimation and variability of children's inhalation rates, and (4) current risk assessment methodologies for addressing children. In this article, existing and emerging information relating to these key issues are introduced and discussed in an effort to better understand children's inhalation dosimetry and adverse health effects for risk assessment. While much useful evidence is currently available, additional research and methods are warranted for improved children's health risk assessment.
Acute toxic effects of methyl isocyanate in the rat were determined for two hour exposures to con... more Acute toxic effects of methyl isocyanate in the rat were determined for two hour exposures to concentrations in the range 11 ppm (very slight effect) to 65 ppm (lethality: pulmonary oedema). Changes in the eye, lungs, and behaviour were noted. Eye changes were confined to erosions of the corneal epithelium and were most severe at intermediate levels of exposure. A comparison was made of the effects noted in rats with reported effects on survivors of the Bhopal disaster. Urinary thiocyanate concentrations in exposed rats were found to be reduced relative to control values.
Polychlorinated biphenyls (PCBs) are ubiquitous toxic contaminants. Health risk assessment for th... more Polychlorinated biphenyls (PCBs) are ubiquitous toxic contaminants. Health risk assessment for this class of chemicals is complex: the current toxic equivalency factor (TEF) method covers dioxin-like (DL-) PCBs, dibenzofurans, and dioxins, but excludes non-DL-PCBs. To address this deficiency, we evaluated published data for several PCB congeners to determine common biomarkers of effect. We found that the most sensitive biomarkers for DL-non-ortho-PCB 77 and PCB 126 are liver enzyme (e.g., ethoxyresorufin-O-deethylase, EROD) induction, circulating thyroxine (T4) decrease, and brain dopamine (DA) elevation. For DL-ortho-PCB 118 and non-DL-ortho-PCB 28 and PCB 153, the most sensitive biomarkers are brain DA decrease and circulating T4 decrease. The only consistent biomarker for both DL- and non-DL-PCBs is circulating T4 decrease. The calculated TEF-(TH), based on the effective dose to decrease T4 by 30% (ED(30)) with reference to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is identical to both TEF-(WHO98) and TEF-(WHO05) for TCDD and DL-PCBs (correlation coefficients are r=1.00, P<0.001; and r=0.99, P<0.001, respectively). We conclude that T4 decrease is a prospective biomarker for generating a new TEF scheme which includes some non-DL-congeners. The new TEF-(TH) parallels the TEF-(WHO) for DL-PCBs and, most importantly, is useful for non-DL-PCBs in risk assessment to address thyroid endocrine disruption and potentially the neurotoxic effects of PCBs.
Methodologies for derivation, listing of available values, and adjustments to allow for early lif... more Methodologies for derivation, listing of available values, and adjustments to allow for early life stage exposures.
trestle were engulfed in flame. The trestle, largely constructed of creosote-treated wood ties an... more trestle were engulfed in flame. The trestle, largely constructed of creosote-treated wood ties and structural beams, continued to burn uncontained for 48 hours. Smoke from the fire was most intense during the first two days of the event. Initially, a large column of black smoke rose directly from the site in a vertical plume, flattening out at 1400-2000 feet elevation (see pictures, Appendix A). Predominant weather conditions throughout most of the fire allowed the thick black smoke to disperse high in the atmosphere, reducing exposures in the Sacramento area. Late Friday night and into Saturday morning, however, portions of Sacramento, Yolo, and Sutter counties were impacted with smoke as the weather and wind conditions changed. Particulate matter concentrations rose dramatically at one air monitoring location to levels considered unhealthy for sensitive groups. Fortunately, the worst air quality readings measured at this site lasted only a matter of hours before clearing. Particul...
... and Dr Martyn T. Smith (School of Public Health, University of California, Berkeley) for cons... more ... and Dr Martyn T. Smith (School of Public Health, University of California, Berkeley) for constructive discussions on aspects of urethane metabolism and carcinogenesis. They also thank Anita Vallejo and Mary King for secretarial assistance. Andrew G. Salmon Lauren Zeise ...
The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588, Connelly) was enact... more The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588, Connelly) was enacted in September 1987. Under this Act, stationary sources of air pollution are required to report the types and quantities of certain substances their facilities routinely release into the air. The goals of the Air Toxics "Hot Spots" Act are to collect emission data, identify facilities having localized impacts, ascertain health risks posed by those facilities, notify nearby residents of significant risks and reduce emissions from significant sources. The Technical Support Document for Cancer Potency Factors (TSD) contains cancer unit risks and potency factors for 107 of the 201 carcinogenic substances or groups of substances for which emissions must be quantified in the Air Toxics Hot Spots program. These unit risks are used in the cancer risk assessment of facility emissions. The purposes of this revision to the TSD is to provide updated calculation procedures used to derive t...
Research on disease causation often attempts to isolate the effects of individual factors, includ... more Research on disease causation often attempts to isolate the effects of individual factors, including individual genes or environmental factors. This reductionist approach has generated many discoveries, but misses important interactive and cumulative effects that may help explain the broad range of variability in disease occurrence observed across studies and individuals. A disease rarely results from a single factor, and instead results from a broader combination of factors, characterized here as intrinsic (I) and extrinsic (E) factors. Intrinsic vulnerability or resilience emanates from a variety of both fixed and shifting biological factors including genetic traits, while extrinsic factors comprise all biologically-relevant external stressors encountered across the lifespan. The I×E concept incorporates the multi-factorial and dynamic nature of health and disease and provides a unified, conceptual basis for integrating results from multiple areas of research, including genomics, ...
Journal of Toxicology and Environmental Health Part a, Dec 20, 2007
Substantial effort has been invested in improving children&am... more Substantial effort has been invested in improving children's health risk assessment in recent years. However, the body of scientific evidence in support of children's health assessment is constantly advancing, indicating the need for continual updating of risk assessment methods. Children's inhalation dosimetry and child-specific adverse health effects are of particular concern for risk assessment. When focusing on this topic within children's health, key issues for consideration include (1) epidemiological evidence of adverse effects following children's exposure to air pollution, (2) ontogeny of the lungs and effects on dosimetry, (3) estimation and variability of children's inhalation rates, and (4) current risk assessment methodologies for addressing children. In this article, existing and emerging information relating to these key issues are introduced and discussed in an effort to better understand children's inhalation dosimetry and adverse health effects for risk assessment. While much useful evidence is currently available, additional research and methods are warranted for improved children's health risk assessment.
Acute toxic effects of methyl isocyanate in the rat were determined for two hour exposures to con... more Acute toxic effects of methyl isocyanate in the rat were determined for two hour exposures to concentrations in the range 11 ppm (very slight effect) to 65 ppm (lethality: pulmonary oedema). Changes in the eye, lungs, and behaviour were noted. Eye changes were confined to erosions of the corneal epithelium and were most severe at intermediate levels of exposure. A comparison was made of the effects noted in rats with reported effects on survivors of the Bhopal disaster. Urinary thiocyanate concentrations in exposed rats were found to be reduced relative to control values.
Polychlorinated biphenyls (PCBs) are ubiquitous toxic contaminants. Health risk assessment for th... more Polychlorinated biphenyls (PCBs) are ubiquitous toxic contaminants. Health risk assessment for this class of chemicals is complex: the current toxic equivalency factor (TEF) method covers dioxin-like (DL-) PCBs, dibenzofurans, and dioxins, but excludes non-DL-PCBs. To address this deficiency, we evaluated published data for several PCB congeners to determine common biomarkers of effect. We found that the most sensitive biomarkers for DL-non-ortho-PCB 77 and PCB 126 are liver enzyme (e.g., ethoxyresorufin-O-deethylase, EROD) induction, circulating thyroxine (T4) decrease, and brain dopamine (DA) elevation. For DL-ortho-PCB 118 and non-DL-ortho-PCB 28 and PCB 153, the most sensitive biomarkers are brain DA decrease and circulating T4 decrease. The only consistent biomarker for both DL- and non-DL-PCBs is circulating T4 decrease. The calculated TEF-(TH), based on the effective dose to decrease T4 by 30% (ED(30)) with reference to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is identical to both TEF-(WHO98) and TEF-(WHO05) for TCDD and DL-PCBs (correlation coefficients are r=1.00, P<0.001; and r=0.99, P<0.001, respectively). We conclude that T4 decrease is a prospective biomarker for generating a new TEF scheme which includes some non-DL-congeners. The new TEF-(TH) parallels the TEF-(WHO) for DL-PCBs and, most importantly, is useful for non-DL-PCBs in risk assessment to address thyroid endocrine disruption and potentially the neurotoxic effects of PCBs.
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