?/EPA United States Environmental Protection Agency Office of Water EPA820-F-15-008 November 2015 Draft Aquatic Life Ambient Water Quality Criteria Update for Cadmium - 2015 Summary EPA is updating its national recommended ambient water quality criteria for cadmium in order to reflect the latest scientific information. The updated criteria reflect the inclusion of new laboratory aquatic toxicity tests with cadmium published since EPA's 2001 criteria document. In addition, the effect of total hardness on cadmium toxicity was also revised using the newly acquired data. The draft updated criteria document has undergone an external peer review that was completed in 2015. EPA will accept written comments from the public for 60 days once announced in the Federal Register. EPA will then consider the comments that were submitted, and revise and publish the final criteria document. Once finalized, EPA's water quality criteria for cadmium will provide recommendations to states and tribes authorized to establish water quality standards under the Clean Water Act. Background EPA published the original national recommended cadmium aquatic life criteria in 1980 with subsequent revisions in 1985,1990,1996 and 2001. In 1985, acute toxicity values were lowered to better protect rainbow trout, the most sensitive species. In 2001, criteria were developed for dissolved cadmium instead of total recoverable cadmium to more accurately account for bioavailability and reflect the latest EPA policy for metals risk assessment. Each update has included updated science and additional aquatic toxicity studies. EPA developed the draft 2015 updated national recommended aquatic life criteria for cadmium using the best available science. What is Cadmium? Cadmium is a relatively rare, naturally occurring metal found in mineral deposits and distributed ubiquitously at low concentrations in the environment. Cadmium's primary industrial uses are manufacturers of batteries, pigments, plastic stabilizers, metal coatings, alloys and electronics. Recently cadmium has been used in manufacturing nanoparticles for use in solar cells and color displays. How Does Cadmium Enter Surface Waters? Cadmium enters the environment by natural and human processes, however, human sources, such as mining and urban processes, are responsible for contributing approximately 90 percent of the cadmium found in surface waters. How Does Cadmium Affect Aquatic Life? Cadmium is a non-essential metal with no biological function in aquatic life. Chronic exposure leads to adverse effects on growth, reproduction, immune and endocrine systems, development and behavior in aquatic organisms. What are National Recommended Aquatic Life Criteria? Ambient water quality criteria for the protection of aquatic life are numeric concentrations of pollutants, with specific recommendations on the duration and frequency of those concentrations, in surface waters that are protective of aquatic life designated uses. Under Clean Water Act section 304(a), EPA is directed to develop and publish water quality criteria that reflect the latest scientific knowledge. Water quality criteria are based solely on data and ------- scientific judgments about the relationship between pollutant concentrations and potential environmental and human health effects. EPA's recommended water quality criteria are not rules, nor do they automatically become part of a state's water quality standards. States must adopt into their standards water quality criteria that protect the designated uses of the water bodies within their area. These can include scientifically defensible site- specific criteria that are different from EPA's national recommended criteria, as long as the site-specific criteria are protective of the designated use. Water quality criteria are not effective under the Clean Water Act until they have been adopted into state water quality standards and approved by EPA. What Are the 2015 Draft Recommended Water Quality Criteria for Cadmium? In the 2015 draft, EPA recommends: the one-hour freshwater acute criterion maximum concentration not exceed 2.1 u.g/L. the four-day average freshwater chronic criterion magnitude not exceed 0.73u.g/L the one-hour estuarine/marine acute criterion maximum concentration not exceed 35 u.g/L. the four-day average estuarine/marine chronic criterion magnitude not exceed 8.3 u.g/L. The recommended frequency of exceedance for the above is no more than once every three years. How Do the Draft 2015 Criteria Compare to the Previously Recommended 2001 Criteria? The draft 2015 updated criteria reflect data for 70 new species and 49 new genera. The draft 2015 freshwater acute criterion (2.1 micrograms per liter) for dissolved cadmium is approximately the same as the 2001 acute criterion (2.0 micrograms per liter). The draft 2015 freshwater chronic criterion (0.73 micrograms per liter) for dissolved cadmium is slightly higher (less stringent) compared to the 2001 criterion (0.25 micrograms per liter). These modest increases are primarily due to the inclusion of new toxicity studies. As in the 2001 criteria, the draft 2015 freshwater acute criterion was derived to be protective of endangered species and lowered further to protect the commercially and recreationally important rainbow trout. In addition, the duration of the 2015 acute criterion was changed to one-hour. Both changes are consistent with EPA's current aquatic life criteria guidelines. The draft 2015 estuarine/marine acute criterion for dissolved cadmium (35 micrograms per liter) is slightly lower (more stringent) than the 2001 acute criterion (40 micrograms per liter), which is primarily due to the addition of new toxicity studies for sensitive genera. The draft 2015 estuarine/marine chronic criterion (8.3 micrograms per liter) is also slightly more stringent than the 2001 chronic criterion (8.8 micrograms per liter), due the consideration of more species in the chronic criterion development. The draft 2015 criteria for dissolved cadmium can be found in Table 1. Table 1. Summary of 2015 Draft Aquatic Life AWQC for Cadmium. Freshwater (Total Hardness = 100 mg/L as CaCO3)a Estuarine/marine 2015 AWQC Update Acute (1-hour, dissolved Cd)c 2.1 ug/Lb 35 ug/L Chronic (4-day, dissolved Cd) 0.73 ug/L 8.3 ug/L a Freshwater acute and chronic criteria are hardness-dependent and were normalized to a hardness of 100 mg/L as CaCOs to allow the presentation of representative criteria values. b Lowered to protect the commercially and recreationally important species (rainbow trout), as per the 1985 Guidelines, Stephen et al. (1985). °The duration of the 2015 acute criteria was changed to 1-hour to reflect the 1985 Guidelines-based recommended acute duration. How to View the Criteria Document and Supporting Information: EPA has established an official public docket for this action under Docket ID No. EPA-HQ-OW-2015-0753, accessed at www.regulations.gov. You may also download the document and supporting information from EPA's aquatic life criteria website at: http://www.epa.gov/wqc/aquatic-life-criteria- cadmium Where can I find more information? Please contact Mike Elias by email at elias.mike@epa.gov. ------- |