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Aquatic Plant Water Quality Criteria
Citation:
Thursby, G. AND M. Lewis. Aquatic Plant Water Quality Criteria. Presented at Society of Environmental Toxicology and Chemistry (SETAC) North America 34th Annual Meeting, Nashville, TN, November 17 - 21, 2013.
Impact/Purpose:
This research builds upon recent work completed as part of a data harmonization effort between the Office of Pesticides Programs and the Office of Water. That original effort provided evidence for the utility of minimal aquatic plant data sets for the potential to derive species sensitivity distributions, but was limited primarily to herbicides. This task will expand the categories of compounds (and thus the modes-of-action), as well as provide information from which OW can develop guidance for minimal data requirements for aquatic plants in the derivation of Aquatic Life Water Quality Criteria.
Description:
The USEPA, as stated in the Clean Water Act, is tasked with developing numerical Aquatic Life Critiera for various pollutants found in the waters of the United States. These criteria serve as guidance for States and Tribes to use in developing their water quality standards. The Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses (“the 1985 Guidelines”) describes the current USEPA methodology for deriving aquatic criteria. The criteria are primarily derived from animal toxicity data. An acute criterion uses a minimum of eight acute toxicity values for animals. A chronic criterion uses the most sensitive of the final chronic value (FCV) for animals or the final plant value (FPV). In practice, however, the chronic criterion has almost always been driven by the FCV. More recently, plant data have been given more consideration in the development of Aquatic Life Criteria, especially for herbicides. There are some limitations; however, associated with the use of the FPV because of an insufficient description of minimum data requirements for plants within the 1985 Guidelines. The availability of a more complete plant toxicity database is desirable. This would allow the USEPA to provide a more definitive recommendation for the optimal minimum dataset needed to assess the risk of chemicals to aquatic plants. This presentation will discuss the status of the current effort for creating a methodology for the derivation of aquatic plant water quality criteria. The majority of the data for the analyses used in that derivation comes from EPA’s publicly accessible ECOTOX database.