The Analysis, Communication, and Perception of Risk, 1991
Risk assessment of environmental contaminants is dependent on the availability of compound-specif... more Risk assessment of environmental contaminants is dependent on the availability of compound-specific toxicologic information. When this information is not available, it may be possible to employ structure-activity relationship (SAR) methods to predict the toxicologic activity. A brief introduction to SAR methodologies, in particular Quantitative SAR (QSAR) is presented with a summary of the major concerns regarding their application in the regulatory setting. An example of the application of QSAR in assessing the risks of drinking water contaminants is presented. This example uses QSAR methodologies to predict the carcinogenicity and mutagenicity of compounds about which there is either limited or no experimental information regarding these properties. The approach utilizes an existing decision framework developed by the ground water and potable water programs in New Jersey which regulates these contaminants at a 5 ppb level for carcinogens and 50 ppb for noncarcinogens.
As part of a program for evaluation of environmental contaminants in drinking water, risk assessm... more As part of a program for evaluation of environmental contaminants in drinking water, risk assessments are being conducted to develop Public Health Goals (PHGs) for chemicals in drinking water, based solely on public health considerations. California's Safe Drinking Water Act of 1996 mandated the development of PHGs for over 80 chemicals by 31 December 1999. The law allowed these levels to be set higher or lower than federal maximum contaminant levels (MCLs), including a level of zero if data are insufficient to determine a specific level. The estimated safe levels and toxicological rationale for the first 26 of these chemicals are described here. The chemicals include alachlor, antimony, benzo[a]pyrene, chlordane, copper, cyanide, dalapon, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 2,4-D, diethylhexylphthalate, dinoseb, endothall, ethylbenzene, fluoride, glyphosate, lead, nitrate, nitrite, oxamyl, pentachlorophenol, picloram, trichlorofluoromethane, trichlorotrifluoroethane, uranium and xylene(s). These risk assessments are to be considered by the State of California in revising and developing state MCLs for chemicals in drinking water (which must not exceed federal MCLs). The estimates are also notable for incorporation or consideration of newer guidelines and principles for risk assessment extrapolations.
Journal of Environmental Science and Health, Part C, 2011
Chloro-s-triazines have been a mainstay of preemergent pesticides for a number of decades and hav... more Chloro-s-triazines have been a mainstay of preemergent pesticides for a number of decades and have generally been regarded as having low human toxicity. Atrazine, the major pesticide in this class, has been extensively studied. In a number of experimental studies, exposure to high doses of atrazine resulted in increased weight loss not attributable to decreased food intake. Chronic studies of atrazine and simazine and their common metabolites show an elevated incidence of mammary tumors only in female Sprague Dawley (SD) rats. On the basis of the clear tumor increase in female SD rats, atrazine was proposed to be classified as a likely human carcinogen by US Environmental Protection Agency (EPA) in 1999. With Fischer rats, all strains of mice, and dogs, there was no evidence of increased incidence of atrazine-associated tumors of any type. Evidence related to the pivotal role of hormonal control of the estrus cycle in SD rats appears to indicate that the mechanism for mammary tumor induction is specific to this strain of rats and thus is not relevant to humans. In humans the menstrual cycle is controlled by estrogen released by the ovary rather than depending on the LH surge, as estrus is in SD rats. However, the relevance of the tumors to humans continues to be debated based on endocrine effects of triazines. No strong evidence exists for atrazine mutagenicity, while there is evidence of clastogenicity at elevated concentrations. Atrazine does not appear to interact strongly with estrogen receptors α or β but may interact with putative estrogen receptor GPR30 (G-protein-coupled receptor). A large number of epidemiologic studies conducted on manufacturing workers, pesticide applicators, and farming families do not indicate that triazines are carcinogenic in these populations. A rat-specific hormonal mechanism for mammary tumors has now been accepted by US EPA, International Agency for Research on Cancer, and the European Union. Chlorotriazines do influence endocrine responses, but their potential impact on humans appears to be primarily on reproduction and development and is not related to carcinogenesis.
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
Environmental Assessment) and the faculty members of the University of California with whom the O... more Environmental Assessment) and the faculty members of the University of California with whom the Office of Environmental Health Hazard Assessment contracted through the University of California Office of the President for their peer reviews of the public health goal documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. (OEHHA) to perform risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. Section 116365 specif...
The Analysis, Communication, and Perception of Risk, 1991
Risk assessment of environmental contaminants is dependent on the availability of compound-specif... more Risk assessment of environmental contaminants is dependent on the availability of compound-specific toxicologic information. When this information is not available, it may be possible to employ structure-activity relationship (SAR) methods to predict the toxicologic activity. A brief introduction to SAR methodologies, in particular Quantitative SAR (QSAR) is presented with a summary of the major concerns regarding their application in the regulatory setting. An example of the application of QSAR in assessing the risks of drinking water contaminants is presented. This example uses QSAR methodologies to predict the carcinogenicity and mutagenicity of compounds about which there is either limited or no experimental information regarding these properties. The approach utilizes an existing decision framework developed by the ground water and potable water programs in New Jersey which regulates these contaminants at a 5 ppb level for carcinogens and 50 ppb for noncarcinogens.
As part of a program for evaluation of environmental contaminants in drinking water, risk assessm... more As part of a program for evaluation of environmental contaminants in drinking water, risk assessments are being conducted to develop Public Health Goals (PHGs) for chemicals in drinking water, based solely on public health considerations. California's Safe Drinking Water Act of 1996 mandated the development of PHGs for over 80 chemicals by 31 December 1999. The law allowed these levels to be set higher or lower than federal maximum contaminant levels (MCLs), including a level of zero if data are insufficient to determine a specific level. The estimated safe levels and toxicological rationale for the first 26 of these chemicals are described here. The chemicals include alachlor, antimony, benzo[a]pyrene, chlordane, copper, cyanide, dalapon, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 2,4-D, diethylhexylphthalate, dinoseb, endothall, ethylbenzene, fluoride, glyphosate, lead, nitrate, nitrite, oxamyl, pentachlorophenol, picloram, trichlorofluoromethane, trichlorotrifluoroethane, uranium and xylene(s). These risk assessments are to be considered by the State of California in revising and developing state MCLs for chemicals in drinking water (which must not exceed federal MCLs). The estimates are also notable for incorporation or consideration of newer guidelines and principles for risk assessment extrapolations.
Journal of Environmental Science and Health, Part C, 2011
Chloro-s-triazines have been a mainstay of preemergent pesticides for a number of decades and hav... more Chloro-s-triazines have been a mainstay of preemergent pesticides for a number of decades and have generally been regarded as having low human toxicity. Atrazine, the major pesticide in this class, has been extensively studied. In a number of experimental studies, exposure to high doses of atrazine resulted in increased weight loss not attributable to decreased food intake. Chronic studies of atrazine and simazine and their common metabolites show an elevated incidence of mammary tumors only in female Sprague Dawley (SD) rats. On the basis of the clear tumor increase in female SD rats, atrazine was proposed to be classified as a likely human carcinogen by US Environmental Protection Agency (EPA) in 1999. With Fischer rats, all strains of mice, and dogs, there was no evidence of increased incidence of atrazine-associated tumors of any type. Evidence related to the pivotal role of hormonal control of the estrus cycle in SD rats appears to indicate that the mechanism for mammary tumor induction is specific to this strain of rats and thus is not relevant to humans. In humans the menstrual cycle is controlled by estrogen released by the ovary rather than depending on the LH surge, as estrus is in SD rats. However, the relevance of the tumors to humans continues to be debated based on endocrine effects of triazines. No strong evidence exists for atrazine mutagenicity, while there is evidence of clastogenicity at elevated concentrations. Atrazine does not appear to interact strongly with estrogen receptors α or β but may interact with putative estrogen receptor GPR30 (G-protein-coupled receptor). A large number of epidemiologic studies conducted on manufacturing workers, pesticide applicators, and farming families do not indicate that triazines are carcinogenic in these populations. A rat-specific hormonal mechanism for mammary tumors has now been accepted by US EPA, International Agency for Research on Cancer, and the European Union. Chlorotriazines do influence endocrine responses, but their potential impact on humans appears to be primarily on reproduction and development and is not related to carcinogenesis.
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
California with whom OEHHA contracted through the UC Office of the President for their peer revie... more California with whom OEHHA contracted through the UC Office of the President for their peer reviews of the PHG documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. The Act requires that PHGs be set in accordance with the following criteria: 1. PHGs for acutely toxic substances shall be set at levels at which no known or anticipated adverse effects on health...
Environmental Assessment) and the faculty members of the University of California with whom the O... more Environmental Assessment) and the faculty members of the University of California with whom the Office of Environmental Health Hazard Assessment contracted through the University of California Office of the President for their peer reviews of the public health goal documents, and gratefully acknowledge the comments received from all interested parties. This Public Health Goal (PHG) technical support document provides information on health effects from contaminants in drinking water. PHGs are developed for chemical contaminants based on the best available toxicological data in the scientific literature. These documents and the analyses contained in them provide estimates of the levels of contaminants in drinking water that would pose no significant health risk to individuals consuming the water on a daily basis over a lifetime. (OEHHA) to perform risk assessments and adopt PHGs for contaminants in drinking water based exclusively on public health considerations. Section 116365 specif...
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