The Safe Drinking Water Act, SDWA, is the Federal law that protects the public from drinking water contaminants that pose a known health concern. Only 91 contaminants are regulated by the Safe Drinking Water Act, yet according to the U.S. Environmental Protection Agency, EPA, more than 80,000 chemicals are used within the United States. Not every drinking water contaminant with health consequence gets regulated because they may not be widely present in source waters. And not every regulated contaminant has health consequence. Some contaminants are regulated to control taste and odor. Though the SDWA was adopted in 1974, it has had significant amendments in 1986 and 1996 that added explicit health goals, risk management approaches and methods of gathering data to allow the SDWA to continue to evolve and ensure the public water supply systems in the United States remains among the safest in the world.
The 1996 amendments to the SDWA created the Unregulated Contaminant Monitoring Rule, UCMR. This is the tool the EPA uses to determine if there are contaminants likely to pose a risk to the health of the nation. A contaminant is identified as being of a possible health concern in drinking water, by states, water systems, scientists or other sources. Health information is collected and if deemed appropriate, occurrence and exposure information are collected using the UCMR data collection program for preliminary risk assessment then a determination is then made on whether there exists an opportunity to reduce public health risks by regulation and the contaminant is then added to the Drinking Water Contaminant Candidate List. The 1996 Safe Drinking Water Act (SDWA) amendments require that once every five years, EPA issue a new list of no more than 30 unregulated contaminants to be monitored by public water systems. The national sampling program provides the EPA with a scientifically valid database on the occurrence of these emerging contaminants in drinking water supplies.
The third Unregulated Contaminant Monitoring Rule list (UCMR 3) from the EPA was finalized and signed on April 16, 2012. The final version of the UCMR 3 requires public water systems, PWSs, serving more than 100,000 people to monitor their source and finished water for 30 contaminants using EPA approved analytical methods during 2013-2015 and provide the data to the EPA. Some smaller systems will be required to perform testing also, but EPA will pay for the analysis of all samples from systems serving 10,000 or fewer people and provide some technical assistance for sampling. In addition, EPA will select 800 representative PWSs serving 1,000 or fewer people that do not disinfect. These PWSs with wells that are located in areas of karst or fractured bedrock, will participate in monitoring for the 2 viruses during a 12-month period from January 2013 through December 2015. (This might be of particular interest to those in Raspberry Falls and Evergreen areas of Loudoun and Prince William Counties.) In all approximately 6,000 PWSs will collect data for a 12 months period creating a very powerful database so that overall exposure can be assessed.
EPA anticipates spending $20 million to subsidize the sampling and analysis in the small water systems, but the bulk of the sampling and analysis will be paid for by the large PWSs and ultimately by their rate payers. In this largest of systems, the anticipated cost of $50,000-$100,000 is not a significant burden, but on the mid-size systems the cost is noticeable. UCMR 2 cost Fairfax Water $50,000 in analysis and was entirely non-detect for all substances, but nationally, the nitrosamines were detected in 25% of the water systems tested. The levels detected ranged from 0.002-0.630 parts per billionwith an average of 0.009 ppb and might result in a regulatory standard for NDMAor all the nitrosamines. The only other UCMR 2 contaminants to appear at more than two of the 1,200 sample locations was the appearance of acetanilide pesticide degradation products in less than 5% of water systems testing. The levels found were up to 4 ppb and averaged less than 2 ppb. This is the only way EPA can gather data and determine if the population as a whole is being exposed to these substances and the levels of exposure. This is a primary data source for the EPA uses to make regulatory decisions for emerging contaminants. EPA has just opened nominations for the next list, UCMR 4.
No actions have yet been taken as a result of the finding of UCMR 2, but N-nitorsodimethylamine, NDMA, may now be listed on the Drinking Water Contaminate Candidate List for potential regulatory action, but when I called the EPA to verify, they asked I submit my questions by email (which I did) and simply sent links to the Federal Register announcing the UCMR 3 which states “guide the
conduct of the Contaminant Candidate List (CCL) process and support the Administrator in making regulatory decisions for contaminants in the interest of protecting public health, as required under SDWA.” That was a frustrating waste of effort. NDMA is a carcinogen known to be present in various foods and industrial products. The EPA hasestablished a 10(-6) cancer risk level for NDMA of 0.7 ng/l. NDMA has been found in the effluents of various water and wastewater plants, but its formation mechanism is not fully understood. As I understand it from other sources there is consideration of regulation on all nitrosamines.
EPA selected the contaminants by first reviewing the agency’s lists of contaminants that need additional research to support future drinking water protections, from states monitoring programs and recommendations from public hearings and comments. The contaminants selected are known or anticipated to occur in public water systems or were selected based on current occurrence research and health-risk factors. Hexavalent chromium was the last addition, added to the list after comments to the proposed list strongly supported its inclusion. This final list includes 6 heavy metals, 7 volatile organic compounds, 7 hormones, 6 perflorinated compounds, 2 viruses, chlorate and 1,4 dioxane. The complete list can be viewed on the EPA website. These contaminants that are not regulated by the National Primary Drinking Water Regulations; are anticipated to occur at public water systems; and may warrant regulation under the Safe Drinking Water Act. The EPA is using the UCMR 3 to determine if these substances are present in drinking water supplies throughout the nation and what levels. In the past 15 years, concerns have been raised about the fate and effects of these emerging contaminants of concern being released into watersheds through upland runoff from both urban and agricultural lands, sewage discharges, and industrial releases. Many of these routes of release are almost constant at very low levels and without widespread sampling and appropriate analysis it is impossible to know what substances might be a real threat to human health.
Chemicals are everywhere in our modern world, they exist in pharmaceuticals, household products, personal care products, plastics, pesticides, industrial chemicals, human and animal waste; they are in short, all around us. These chemicals include organics, inorganic, polymers, complex reaction products, and biological materials. The technology used for chemical analysis has advanced to the point that it is possible to detect and quantify nearly any compound known to human kind down to less than a nanogram per liter or parts per trillion (1/1,000,000,000,000). This enhanced analytical ability has allowed scientists to discover that trace levels of pharmaceuticals, potential endocrine disrupting compounds (EDC) and other emerging contaminants exist in surface water, have appeared in some groundwater and may to persist in the water through conventional and some advanced treatment trains to appear in our finished drinking water. What we don’t know is how prevalent these contaminants are and if these traces of compounds are a health concern.
The emerging contaminants lack human health standards so the first step is to identify what substances are present at what levels in the environment. EPA has begun with water not only because there exists a way to mandate the data is collected on a national scale, but everyone drinks and bathes in water. Using the UCMR list to identify substances with widespread exposure through drinking water is the best way to prioritize contaminants. The next step would be to identify the acceptable human exposure level and need for regulation based on presence in the environment. Much of the environmental work in the past has been done on what are called the persistent priority pollutants, such as trace metals, pesticides, PCBs and PAHs, substances that persist in the environment. Many of the emerging contaminants are environmentally non-persistent, but still may have health impacts. A non-persistent chemical breaks down and these breakdown products may be widely present in the environment.