Persistent Organic Pollutants

Persistent organic pollutants (POPs) – particularly chlorinated compounds, such as dioxins, furans, and polychlorinated biphenyls (PCBs) – continue to be detected in the environment and exposure to these compounds have been identified as a potential human health concern. Although these compounds are no longer manufactured, they can still be found in various media including air, soil/sediment, fish, beef, or dairy products. Consequently, humans continue to be exposed to low levels with measurable concentrations of POPs being detected in biomonitoring studies of the U.S. public. As a result, public concerns can be raised when these compounds are detected at Superfund sites, in public school, or in cases of accidental releases (e.g., spills).
Exponent toxicologists review and interpret the data related to the toxicity of dioxins, furans, and PCBs. Our reviews of the data range from detailed examinations of the experimental animal studies to comprehensive weight-of-the-evidence evaluations of the toxicology and epidemiology data for various alleged human health endpoints, such as cancer and diabetes. 

Given our broad-based knowledge of these compounds, Exponent staff have participated in various regulatory meetings related to POPs and have presented comments on the regulatory evaluations of these compounds. We have interacted with California’s OEHHA on related Proposition 65 issues, contributed to Congressional briefings on these compounds, presented on POPs at national and international scientific conferences, and participated in meetings related to EPA’s re-evaluation of dioxins/furans and the current re-examination of PCBs under IRIS.

Hazard identification and dose-response are two critical, toxicology-based elements that are integral to the risk assessment process. Consequently, Exponent toxicologists have been involved in a wide range of risk assessment issues related to POPs, from individual evaluations of consumer products to complex risk assessments as Superfund sites. Specific to Superfund sites, we have assisted the Principal Responsible Parties (PRPs) in understanding the toxicology issues, estimating risks under various exposure scenarios, and developing appropriate risk-based remediation goals.

Exponent toxicologists have widely recognized expertise in this field, especially with regard to assessing allegations of health effects associated with exposure to dioxins and furans, claims of injury from dioxin exposure, allegations of health effects associated with both direct and indirect exposure to PCBs, and claims of exposure to PCBs from caulk in school environments. 


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