Exposure risk assessment guidelines

The cancer risk equation described below estimates tlie incremental individual lifetime cancer risk for simultaneous exposure to several carcinogens and is based on EPA s risk assessment guidelines. Tliis equation represents an approximation of the precise equation for combining risks wliich accounts for tlie joint probabilities of tlie same individual developing cancer as a consequence of exposure to two or more carcinogens. The difference between tlie precise equation and tlie approximation described is negligible for total cancer risks less tlian 0.1. Thus, tlie simple additive equation is appropriate for most risk assessments. The cancer risk equation for multiple substances is given by ... 

Risk assessment is an empirically based process that estimates the risk of adverse effects from exposure of an individual or population to a chemical, physical or biological agent. The OECD test guidelines, the US EPA risk assessment guidelines and additional risk assessment procedures for new and existing chemicals have been published and put into use by many different countries in Europe, the Americas and Asia (United Kingdom Department of Health, 1991,1995 EC, 1994,1996 Health Canada, 1994 IPCS, 1994 Hertel, 1996). A list of assessments produced by various national and international agencies on specific chemicals is included in ECETOC/UNEP (1996). 

RELs). The Air Toxics Hot Spots Program Risk Assessment Guidelines, Part 1 The Determination of Acute Reference Exposure Levels for Airborne Toxicants, March 1999 and the Air Toxics Hot Spots Program Risk Assessment Guidelines, Part III The Determination of Chronic Reference Exposure Levels for Airborne Toxicants, www.oehha.ca.gov/air/allrels.html (accessed 11 May 2009). 

OEHHA (2000) A ir Toxics Hot Spots Program risk assessment guidelines. Part IV. Technical support document for exposure assessment and stochastic analysis. Oakland, CA, California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (http //www.oehha.ca.gov/air/hot spots/pdf/Stoch4f.pdf). 

In addition to the graphic approach for toxicity data and the verification of uncertainty factors, other areas are under study such as route-to-route conversion, high-dose to low-dose extrapolation, approaches to assess the health risk from less-than-lifetime exposures, and refinement of risk assessment approaches for chemical mixtures. All of these areas represent progress in the methods used for risk assessment of single chemicals and chemical mixtures. With the new risk assessment guidelines currently being developed, the U.S. EPA can move forward to better and more consistent health risk assessments. 

To assess tlie overall potential for noncarcinogenic effects posed by more dian one chemical, a liazard index (HI) approach has been developed based on EPA s Guidelines for Healdi Risk Assessment of Chemical Mixtures. This approach assumes that simultaneous subtlu eshold exposures to several chemicals could result in an adverse healtli effect. It also assumes tliat tlie magnitude of the adverse effect will be proportional to tlie sum of the ratios of the subtlireshold exposures to acceptable exposures. The non cancer hazard index is equal to tlie sum of the hazard quotients, as described below, where E and tlie RfD represent the same exposure period (e.g., subclironic, clironic, or shorter-term). 

In 1996, the US Senate and House of Representatives passed the Food Quality Protection Act (FQPA). In order to make their exposure and risk assessments as accurate as possible, the US ERA Office of Pesticide Programs (OPP) has established guidelines to determine a value to assign for NDs. These guidelines can be summarized... 

Human risk assessment (HRA) was done applying guidelines from the Italian Institute for Environmental Protection and Research (ISPRA) and selecting water ingestion as route of exposure for human health assessment [20]. According to the... 

Henderson, R.F. 1992. Short-term exposure guidelines for emergency response The approach of the Committee on Toxicology. Pp. 89—92 in Conference on Chemical Risk Assessment in the Department of Defense (DoD) Science, Policy, and Practice, H.J.Clewell, III, ed. American Conference of Governmental Hygienists, Cincinnati, OH. 

In order to understand the use and intent of the various immunotoxicology regulatory guidelines and guidance documents, the difference between two concepts familiar to toxicologists should be emphasized. Hazard, identification refers to a method which is essentially qualitative that is, it is designed to detect the ability of a test article to produce a certain (in the context of toxicology) adverse effect, without reference to exposure issues. Risk assessment, on the other hand, takes into consideration method, dose, and duration of exposure, condition(s) of the exposed population, and concurrent... 

EPA guidelines for exposure and risk assessment and the agency s integrated risk information system (IRIS) http //cfpub.epa.gov/ncea/... 

---