Emerging Contaminants Summit
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Emerging Contaminants Summit
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Usha Vedagiri Usha Vedagiri
Principal Risk Assessor

Dr. Usha Vedagiri is a principal risk assessor at Wood with more than 20 years of national and international experience in human health and ecological risk assessment. She provides technical leadership on risk assessments as well as frequently communicating risk assessment results to technical and non-technical audiences. She is actively engaged in several ITRC teams dealing with emerging contaminants and new methods including PFAS, TPH Risk Evaluation and Bioavailability. She has been tracking technical and regulatory developments in microplastics for several years.


Microplastics: Current regulatory status and trends in risk assessment vs risk perception.

Authors:Usha Vedagiri (USA), Liz Nicol (UK), Julius Kreissig (UK), Caryn Kelly (USA)

Microplastics (particles less than 5 mm in size) form an important emerging category of physical and chemical contaminants that have elicited global concern and calls for regulatory action. This presentation will review the most commonly expressed perceived ecological risks and concerns for Mp, the current state of information as to whether these concerns are supported by the scientific literature and the regulatory approaches taken by the EU and US in approaching Mp. Wood led a project to conduct an initial assessment the risks and potential regulatory options for intentionally added MP for the European Commission, performed an extensive review of Mp literature and developed recommendations to assist the European Chemicals Agency (ECHA) with a potential REACH restriction for intentionally added Mp. USEPA held a Microplastics Experts Workshop in 2017 that resulted in a number of technical recommendations to better understand the nature and magnitude of Mp issues and is currently evaluating initiatives to address trash and Mp under existing regulatory programs such as CERCLA, RCRA and the Clean Water Act. Strongly-held public perceptions regarding the physical hazards and risks of Mp to aquatic and marine life focus on reports of ingestion and accumulation of plastics in the gut, translocation and transfer through the food web and subsequent adverse effects such as starvation and mortality. Public concerns have also been expressed about biological exposure to persistent chemical contaminants that may be adsorbed to the Mp surfaces. A large amount of literature published in the last 10 years provides documentation of the widespread exposure of aquatic life to Mp but is less clear on documented or predictable dose-response information and quantitative predictions of risks. Acceptable physical risk levels for Mp in water have been estimated on the basis of density (particles per liter) and concentration (mass per liter) and some studies have estimated that these levels are most likely to be exceeded only in certain types of localized environments or activities, but unlikely to be exceeded in the open marine environment. This type of acceptable risk level approach to Mp may be at variance with worst-case risk perceptions. Distinctions between intentionally added and unintentionally-generated Mp are also important to understand when considering regulatory actions. This presentation will present a comparative evaluation of European and US regulatory approaches with regard to understanding and managing ecological risks related to Mp.


Safety of Commercial Food Supplies in the US in relation to PFAS: Are there Reasons for Concern?

Authors:Usha Vedagiri (Wood, Rancho Cordova, CA), Shalene Thomas (Wood, Minneapolis, MN)

This presentation focuses on whether concerns regarding PFAS in the commercial food supply chain are warranted. As public awareness of the wide distribution of PFAS in the environment has grown, so too have concerns about the multiple modes of exposure to PFAS. Numerous publications have documented PFAS occurrence in drinking water, crops and produce grown in PFAS-amended soils, and in fish and shellfish from PFAS-impaired water bodies. Fish consumption has been highlighted as a particular area of concern due to the bioaccumulative nature of PFOS and other long-chain PFAS. Elevated levels of PFAS have been reported in sport fish from PFAS-contaminated water bodies and numerous fish consumption advisories have been developed for recreational anglers and subsistence consumers. However, 90% of the US population actually obtains their fish from commercially-available fish and shellfish products sold at retail markets. Similarly, produce and other dietary items are also mostly derived from purchased sources for the majority of the US population. This presentation summarizes the results of several very recent and earlier “market basket” studies in the US (2010-2019) that analyzed PFAS in retail market fish and shellfish that originated from US and international sources. These studies represented a range of fresh and processed commercial fish products from multiple retail locations around the US. Although it is not possible to sample and analyze the thousands of fish and shellfish supplies that are available commercially, in general, these recent studies found commercial fish supplies to have very low or undetectable concentrations of PFAS and did not identify health concerns for consumers. Thus, there is a difference in the regulatory and risk communication tools that are needed to protect the health of anglers in water bodies with known PFAS contamination versus fish consumers in the general US population. Conclusions and recommendations are presented regarding the importance of appropriate risk communication when addressing PFAS in commercial food supplies such as fish and shellfish.

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