A new study of 201 large municipal water systems in the U.S. found traces of a certain family of toxic chemicals in all of them. The highest levels of these chemicals, known as trihalomethanes, were found in Davenport, Iowa.
The Environmental Working Group published the report by the non-profit's Senior Scientist Renee Sharp and Research Analyst J. Paul Pestano today. You can download the pdf file with graphics here. An appendix on pages 13 through 19 shows annual average levels of trihalomethanes and haloacetic acids at all the water treatment facilities studied. You can read EWG's findings here. Excerpt (emphasis added):
The EPA regulates four members of the trihalomethane family, the best known of which is chloroform, once used as an anesthetic and, in pulp detective stories, to knock out victims. Today, the U.S. government classifies chloroform as a "probable" human carcinogen. California officials consider it a "known" carcinogen. Three other regulated trihalomethanes are bromodichloromethane, bromoform, and dibromochloromethane. hundreds more types of toxic trash are unregulated.
Scientists suspect that trihalomethanes in drinking water may cause thousands of cases of bladder cancer every year. These chemicals have also been linked to colon and rectal cancer, birth defects, low birth weight and miscarriage (NHDES 2006).
When Does Water Treatment Contamination Reach the Danger Point?
An Environmental Working Group analysis of water quality tests conducted in 2011 and made public last year by 201 large American municipal water systems in 43 states has determined that each of these systems detected thihalomethane contamination. In short, more than 100 million Americans served by these large waterworks were exposed to toxic trash.
Only one of the systems studied by EWG - Davenport, Iowa - exceeded the EPA rule barring more than 80 parts per billion of trihalomethanes in drinking water (see Appendix). This legal limit was set in 1998, based on the potential for trihalomethanes to cause bladder cancer. The 80-parts-per-billion standard was part of a major Clinton administration initiative to improve federal drinking water protections under the federal Safe Drinking Water Act.
Yet the significant toxicity of trihalomethanes and other water contaminants generated by water treatment chemicals, documented by large numbers of scientists around the world, makes a compelling case for lowering the federal legal limit to well below 80 parts per billion.
While Davenport was the only location where levels of trihalomethanes averaged above the EPA limit, sampling in many other locations showed occasional spikes above that limit. The systems stayed in compliance by averaging those pollution readings with lower readings taken at different times during the year.
Everyone is at risk for developing bladder cancer, but trihalomethanes present additional risks for pregnant women.
EWG's analysis suggests that many people are likely exposed to far higher concentrations of trihalomethanes than anyone knows. The EPA regulation for these toxic chemicals is based on the system-wide annual average. But in most water systems, trihalomethane contamination fluctuates from month to month, sometimes rising well beyond the 80 parts-per-billion federal cap. Contamination spikes are offset by low readings that keep the systems in legal compliance.
The EPA standard for trihalomethanes is based on preventing bladder cancer, but the agency has noted that that these chemicals may present reproductive and developmental risks as well (EPA 2012a). A spike that lasts three months exposes a pregnant woman and her fetus to excessive trihalomethane for an entire trimester, a critical window of development. Scientific research has shown that such intensive exposure can have serious consequences for the child. Three studies published last year:
Australian scientists found that when women in their third trimester of pregnancy consumed water with 25 parts per billion of chloroform, their newborns were small for their gestational age, meaning that they typically had birth weights in the lowest ten percent of newborns and were at higher risk for a various health problems (Summerhayes 2012).
Canadian researchers found that exposure to more than 100 parts per billion of trihalomethanes during the last trimester of pregnancy was associated with newborns small for their gestational age (Levallois 2012).
Taiwanese researchers linked stillbirth risks to trihalomethane levels as low as 20 parts per billion (Hwang 2012).
Numerous other studies have associated reproductive and developmental problems with trihalomethanes. Among them:
In 2008, scientists from the University of North Carolina found that women exposed to more than 80 parts per billion of trihalomethanes during their third trimester of pregnancy faced twice the risk of delivering a child small for gestational age (Hoffman 2008).
British scientists found a link between 60 parts per billion of trihalomethane exposure and stillbirths (Toledano 2005).
In 2003, a team from the harvard School of Public health linked exposures to more than 80 parts per billion of trihalomethanes during the second trimester of pregnancy to low birth weight and small- for-gestational-age newborns (Wright 2003).
In 2002 researchers at the federal Agency for Toxic Substances and Disease Registry reviewed the findings of 14 major studies and concluded that there was "moderate evidence" for an association between trihalomethane exposure, small-for-gestational-age newborns, neural tube defects and miscarriage (Bove 2002). The neural tube is the structure in the fetus that develops into the brain and spinal cord.
As usual, the self-styled "pro-life" movement is missing in action when water pollutants threaten fetuses' health or lives. Birth defect rates are higher among women exposed to the weed-killer atrazine. Exposure to nitrates is also associated with a higher risk of birth defects and miscarriage. I doubt we'll hear any complaints about trihalomethanes in the local water from the activists in the Quad City area who tried to stop Planned Parenthood from opening a clinic in Davenport.
The Environmental Working Group study notes that a "water pollution cascade from agricultural runoff" forces municipal water treatment facilities to use higher levels of chemicals.
Cleaner source water is critical to breaking this cycle. By failing to protect source water, Congress, EPA and polluters leave Americans with no choice but to treat it with chemical disinfectants and then consume the residual chemicals generated by the treatment process.
For most utilities with chronically high readings of treatment pollutants, cleaning up source water will require aggressive action to reduce agricultural pollution, runoff from suburban sprawl and upstream sewage discharges.