Two public interest groups have issued a report warning of the dangers of what they term "chlorination byproducts" (CBPs) that can pose a threat of cancer, miscarriages and birth defects. While the groups agree that using chlorine as a disinfectant is a critical public health measure, they warn that source water is often contaminated with organic matter that can interact with chlorine to form dangerous byproducts.
"Until Congress and the EPA act to limit pollution from farms and urban runoff so that water entering drinking water treatment plants is much cleaner than it is today, CBP levels will remain at unacceptably high levels," the report states.
The report, "Consider the Source: Farm runoff, chlorination byproducts, and human health," was compiled and published by the Environmental Working Group (EWG) and U.S. Public Interest Research Group (U.S. PIRG).
The EWG analyzed Total Trihalomethane (TTHM) levels in public water supplies from 50 states and Washington, D.C. The report lists 50 U.S. cities that face elevated risk for miscarriage and birth defects resulting from high TTHMs in their drinking water. According to the report, well over half of the pregnancies considered to be at-risk occur in Pennsylvania, Texas, New Jersey and Maryland. The report warns that hundreds of small utilities and some large cities across the country have high levels of TTHMs in their tap water.
"By failing to clean up rivers and reservoirs that provide drinking water for hundreds of millions of Americans, EPA and the Congress have forced water utilities to chlorinate water that is contaminated with animal waste, sewage, fertilizer, algae, and sediment," the report states. "In spite of the diligent efforts of the water utilities to filter and clean the water before they chlorinate, CBP levels remain high in the water consumed by millions of people each day. Approximately 240 million Americans drink tap water contaminated with some level of CBPs."
Based on their findings, the groups made three core recommendations:
- The creation of a nationwide health tracking network to help scientists and policymakers fully understand the link between tap water chlorination byproducts and specific birth defects, cancers, and miscarriage.
- Funding for programs to train operators of small town drinking water systems in improved chlorination techniques.
- A major national effort to clean up drinking water sources, focusing on reducing agricultural and urban pollutants that lead to chlorination byproducts.
According to the report, nearly 30 peer-reviewed epidemiologic studies have linked disinfection byproducts to increased risks of cancer. At current levels in U.S. tap water, EPA estimates that such byproducts cause up to 9,300 cases of bladder cancer each year.
"A growing body of science links CBPs to miscarriages and birth defects, including neural tube defects, low birth weight, and cleft palate. Other health problems from exposure may include other cancers (rectal and colon), kidney and spleen disorders, immune system problems and neurotoxic effects," the report states.
"While there is no known level of exposure to CBPs that does not increase these health risks for consumers, scientists and policymakers would be better equipped to protect public health from CBPs if they had better information on exposures and health outcomes."
The report's authors claim that the U.S. lacks a nationally coordinated network to track birth defects and miscarriages. National cancer incidence data is more complete, but scientists lack data on CBP levels in public water supplies needed to fully understand the link between those byproducts and specific birth defects, cancers, and miscarriage.
Notably, the report said industrial water pollution is not a major contributor to CBPs in tap water. Instead, it said the main causes are sediments, nutrients, and pollution from agricultural and urban runoff, and in some small systems, excess use of chlorine.
This first ever national analysis of chlorination byproducts in tap water from both large and small cities, conducted by the Environmental Working Group, shows that although most water suppliers are in compliance with current and future drinking water standards:
- More than 153,000 pregnancies each year are at increased risk of miscarriage and birth defects from exposure to CBPs in tap water.
- Since 1995, more than 11 million people in 1,044 communities have been served water containing chlorination byproducts for 12 months in a row at levels above the legal limit going into effect in January 2002.
- A handful of large cities with a history of high CBP levels account for a significant portion of the population at risk, including Philadelphia, Washington D.C., San Francisco, Pittsburgh, and Newark NJ
- More than 1,000 small towns (fewer than 10,000 people) have reported potentially dangerous levels of CBPs in their tap water over the past six years. Pregnant women living in small towns supplied by rivers and reservoirs are more than twice as likely to drink tap water with elevated levels of CBPs as women in larger communities. Historically, systems serving fewer than 10,000 people have been exempt from all federal health standards for disinfection byproducts.
For more information on the study, "Consider the Source: Farm runoff, chlorination byproducts, and human health," visit the Environmental Working Group's web site at www.ewg.org, or the Public Interest Research Group site at www.pirg.org. WW/
