Government Watch
Federal court finds some carcinogens safe at low doses A recent federal court decision on safe levels of chloroform in drinking water has ushered in a new era of carcinogenic risk assessment for the U.S. EPA. The controversial approach, which relies heavily on a nonlinear doseresponse model, assumes that some carcinogens are safe at low doses. Although this model is supported by the court, the agency's Science Advisory Board (SAB), and the several scientists are against it and argue that not enough is known about cancer mechanisms to describe the relationship between dose and response in humans at very low doses In its March 31 decision, the U.S. Court of Appeals for the District of Columbia Circuit rejected EPA's final maximum-contaminant-level goal (MCLG) of zero for chloroform in drinking water. The MCLG, originally finalized in November 1999, is an unenforceable standard (Environ. Sci. Technoll.999, 33 (5), ,14A. As s aesult of the court's ruling, EPA has dropped the zero MCLG from its regulations. The court wrote that in using a linear dose-response relationship as a basis for establishing the MCLG, the agency did not use the best available scientific evidence. Chloroform, a known carcinogen, is formed when chlorine for disinfecting drinking water reacts with natural organic compounds in raw water supplies. It is the most common water disinfectant used in the United States and abroad. The court's decision gives EPA the green light to consider evidence for nonzero standards when evaluating risk for other carcinogens in food and water, such as arsenic and atrazine, many inside and outside government said. Indeed, EPA told this court that a nonzero MCLG was more appropriate and argued that the nonlinear approach for chloroform was supported by new mechanistic data. Chloroform will be the first carcinogen for which EPA has considered a hearth standard
above zero {Environ. Sci. Technol, 1998, 32 (9), 208A). When it set the final MCLG of zero, EPA relied on its 1986 Guidelines for Carcinogen Risk Assessment, a document used for all environmental statutes that prescribes a linear dose-response model for known carcinogens. The linear doseresponse model assumes that carcinogens have no safe exposure level. Additional mechanistic data became available just before EPA's deadline to set the final MCLG for chloroform, but the agency had no time to consult with its SAB and therefore set a default MCLG of zero. In February 2000, the SAB agreed that the dose-response curve for chloroform is nonlinear.
"The idea that there is a threshold for carcinogens is an untested hypothesis." —Ron Melnick NIEHS
But not everyone agrees with the court's interpretation. "The idea that there is a threshold for carcinogens is an untested hypothesis, and we need to know more before we change the assumptions underlying the shape of the dose-response curve," said Ron Melnick, toxicologist at the National Institute of Environmental Health Sciences. Although mechanistic data are valuable, "we don't know enough about cancer mechanisms to describe the shape of the dose-response curve at low doses." in point is chloroform where the mechanistic data which shows exactly how certain chemicals cause cancer and purports to show a threshold is inconsistent he said The court's validation of the draft 1996 guidelines "opens the door to a
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new approach," said Denise Robinson, toxicologist with the International Life Sciences Institute, a nonprofit research group. Incorporating mechanistic data into risk analyses "should lead to more certainty and confidence in the result," she concluded. These scientists disagree over whether employing the nonlinear dose-response will result in stricter or laxer standards. But an EPA scientist agreed mat the agency will continue to review mechanistic data and would consider a nonzero standard for certain carcinogenic contaminants when appropriate.
New model reveals 50% funding shortfall for state water quality programs A new model from the U.S. EPA designed to estimate the cost of running state water quality programs has the strong support of state leaders, who call it a significant first step in addressing chronic funding shortfalls. The model estimates that states will need to spend a total of $1.3 billion annually over the next five years, excluding capital cost investments, a figure nearly double the current level. Budget estimates from the model will be key in garnering additional funds from Congress and state legislatures to fully implement the Clean Water Act (CWA) provisions. Completed in March by a working group of state leaders, who urged EPA to help develop such a model, and officials from the agency's Office of Water, the model is a spreadsheetbased program that estimates state resource needs for managing surface water quality programs and identifies funding shortfalls. To run the model, programmers must know the number of stream miles, impaired water bodies, and monitoring sites in a state. EPA and the states are developing another analysis that will calculate infrastructure costs for sewage and drinking water treatment. © 2000 American Chemical Society
So far, the model reveals that the average state should spend about 23% of its total budget on point source ac tivities, 16% on nonpoint sources, 12% on wetlands protection, and 10% on the total maximum daily load pro gram, designed to reduce and cap pol lution from runoff. Cost figures for individual states are not available. The model is the first national ef fort to identify how much states will have to pay to comply with the CWA, said Susan Sylvester, water division administrator in Wisconsin's Depart ment of Natural Resources, who worked on the model. Unlike previous models, this one will give states a fuller accounting of all of the costs involved in implementing a water management program, including la bor, said Sylvester. Previous models estimated funds needed to run 3. per mit program and were based on data such as state population. A large shortfall in water program funding exists thanks to Congress's expansion of state responsibilities without providing additional money, Sylvester said. "The funding gap is huge because the federal financial commitment to the Clean Water Act is far less than necessary to sustain water programs," agreed Linda Eichmiller, deputy director of the Associ ation of State and Interstate Water Pollution Control Administrators.
Farmers say EPA should play no role in land-use decisions A ruling by a federal court support ing the U.S. EPA's position that it can identify as impaired water bodies that are contaminated by runoff is not going stop the multitude of farmers, foresters, and ranchers op posed to the agency's proposed rule to regulate nonpoint source pollu tion. The March 30 ruling from the U.S. District Court for the Northern District of California agreed with EPA that the Clean Water Act (CWA) provides a comprehensive approach for protecting impaired waters, such that cleanup plans Ρ3ΤΊ apply to sedi ment pollution from agricultural and forestry operations as well as other types of nonpoint source runoff The ruling written by U.S. District Court Judge William Alsup rejected claims by landowner Guido Pronsolino and others that EPA had over stepped its CWA authority when it listed the Garcia River in California as
impaired due to sediment runoff {En viron. Sci. Technol. 2000,34, (7(7 168A169A). Pronsolino maintains that the impaired listing and subsequent plans to protect the watershed will prevent him from harvesting for sale hundreds of acres of North Coast redwood trees, said Pronsolino's attorney Russell Eggert of the law firm Mayer, Brown & Piatt. The listing was part of a settle ment agreement reached after a coali tion of environmentalists and fisher men sued EPA in the early 1990s asking it to take over California's total maximum daily load (TMDL) program by listing any impaired waters and developing protection plans EPA listed the Garcia River as impaired due to soil erosion resulting from timber practices But the plaintiff's lawyers in the case Pronsolino v. .PA still believe they are correct. States might include "nonpoint sources in their programs, but EPA doesn't have the authority to force states to do anything about those sources," said Eggert. The plain tiffs have fiied an appeall Local, state, and federal farm orga nizations, including the American Farm Bureau Federation (AFBF) were coplaintiffs in the lawsuit. The AFBF, a powerful lobbying organization, "be lieves the proper place to deal widi
nonpoint sources is at the state and local level," said Don Parrish, an AFBF senior environmental policy analyst. "You can't control runoff; you can only manage it," Parrish said. "And runoff management raises land-use ques tions. We don't believe the federal gov ernment should be in the business of even suggesting what local land use should be." Parrish said AFBF mem bers are highly concerned that EPA's proposed TMDL rule published in Au gust 1999 (Environ. Scii Technol. 1999 4 (11), 446A-447A), will allow the fed eral government to regulate agricultural QIJ ^>j-g^2 Q rts near impaired water bodies and are considering other law suits challenging the TMDL program The final TMDL rule is expected to be released midsummer Elizabeth Fellows in EPA's Office of Water said Alsup's ruling clearly supports the agency's view. The court "ringingly said that nonpoint sources must be in the TMDL plan" for the Garcia River, Fellows said. EPA officials never claimed they have authority to permit nonpoint sources, she added. EPA has always, and will continue, to rely on volun tary programs to control nonpoint pollution. EPA is under a court order in 15 states to establish TIvIDLs ac cording to the agency.
New facilities triple national data on toxic releases For the first time this year, seven new industrial sectors were required to report their 1998 releases under the U.S. EPA's Toxics Release Inventory. Combined with the manufacturing industry, these new sectors bring the 1998 total toxic releases to 7.3 billion pounds, almost triple the amount recounted previously. Overall, the 1998 data show a 45% decrease, or 1.5 billion pounds, among the manufacturing industries, which since 1987 have reported air, water, and land releases of listed chemicals. The 1998 report and links to Web-based tools that can help citizens analyze the data can be found at www.epa.gov/tri.
Note: Releases are in millions of pounds. Source: U.S. EPA.
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