|
|
How the Federal Government, Other States, and the European Union Address Unregulated Contaminants in Drinking Water
2. Agency for Toxic Substances and Disease Registry
|
For Public Comment -- Deadline April 2, 2004
Chemical Mixtures Program
The Agency for Toxic Substances and Disease Registry has been mandated to determine the health impact of exposure to combinations of chemicals. Exposure to two or more chemicals occurs at numerous hazardous waste sites, sometimes by way of more than one exposure route. Meanwhile, the majority of current toxicological research focuses on the health effects of exposure to a single substance. In order to fulfill its mandate, the Agency for Toxic Substances and Disease Registry is engaged in a multi-faceted course of investigation into the human health effects of chemical mixtures, including: (1) identification of the mixtures of highest concern to public health. (2) estimation of the joint toxic action of these chemicals through assessment and laboratory methods, and (3) development of new methodologies for evaluating the health effects of mixtures.
To address the course of investigation, the agency develops Interactions Profiles. Similar to the agency Toxicological Profiles, these documents summarize the health effects caused by exposure to chemicals in a mixture. Other guidance the agency offers or plans to offer include: the development of Guidance Manual for the Assessment of Joint Toxic Action of Chemical Mixtures, which is designed to assist health assessors in determining
the impact of chemical mixture exposure on public health; the development of Minimal Risk Levels for chemical mixtures, which is a paradigm using methods to derive health guidance values for mixtures such as chlorinated dibenzodioxins and polybrominated biphenyls; performance of weight of evidence analyses for combinations of chemicals, used to predict the influence of one chemical on the health effects of another chemical; and performance of laboratory studies in collaboration with other national agencies to validate weight of evidence analyses.
More information on this program can be found at the agency's website:
http://www.atsdr.cdc.gov/mixtures.html"
(Click on the above link to go to that document)
Among the specific objectives of the program are:
Develop methods to evaluate toxicological interactions of chemical mixtures. Trichloroethylene, the most frequently found drinking water contaminant, is being studied in combination with chemicals such as vinyl chloride, arsenic and 1,2-dichloroethane that are found together in water.
Test effects of metal mixtures using laboratory techniques. Simple mixtures of environmentally important chemicals such as arsenic, cadmium, chromium and mercury are being studied.
Improve precision and reliability in toxicity assessment methods for mixtures. Dose-response relationships are being studied using mixtures of liver toxicants such as chloroform and trichloroethylene.
Assess the absorption of toxic chemical mixtures through skin. Mixtures of chemicals such as poly chlorinated biphenyls and pentachlorophenol are being studied in the presence of chemicals that are found together and can influence skin absorption rates.
Develop new methods and protocols to estimate the toxicity of complex mixtures. Mixtures containing polycyclic aromatic hydrocarbons that are found in sediments of certain hazardous waste sites are being studied. Such methods, when fully developed and validated, may be useful to assess the toxicity associated with lifestyle and occupational exposures.
|
 BACK
||
CONTENTS
||
NEXT
||
|
|
|
