These include chloroform, bromoform, bromodichloromethane and dibromochloromethane. The maximum annual average of THMs detected in local water supplies cannot exceed 80 ppb per Environmental Protection Agency (EPA) regulations.
Studies have linked THMs with low birth weight and neurological abnormalities in infants, along with increased incidences of neural tube defects, small body length, and small head size in babies born to women drinking water containing 400 ppb THMs. Research has also linked an increased risk of bladder cancer with exposures of 50 ppb, and first trimester miscarriage in pregnant women drinking water with 75 ppb -- both of which are under the EPA “safe” limit.
Levels of THMs between 80 and 100 ppb and above are associated with increased incidences of neural tube, central nervous system, and major cardiac birth defects.
Haloacetic acids (HAAs):
These include monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid. The maximum annual average of HAAs permitted by EPA regulations is 60 ppb.
Classified by the EPA as possibly carcinogenic to humans because of evidence of carcinogenicity in animals, studies have linked HAAs with an increased risk of cancer, and injury to the brain, nerves, liver, kidneys, eyes and reproductive systems.
Further, the Environmental Working Group (EWG) points out that evidence has shown exposure to HAA during the second and third trimesters of pregnancy may be linked to intrauterine growth retardation and low birth weight. Certain HAAs have also been linked to a disturbance in the balance of the intestinal tract, which could increase the risk of pathogenic bacteria causing illness, particularly in those with compromised immune systems. They have also been shown to be toxic to the sperm of rats at concentrations as low as 10 parts per billion, and to cause a range of neurological effects.
While there are a total of 600 disinfection byproducts that have been identified by EPA scientists, legal limits for levels in tap water have been set for only 11 of them.
How to Find Out Levels of DBPs in Your Area
In 1998 a federal mandate was passed requiring all U.S. water utilities to prepare annual water quality reports, also known as Consumer Confidence Reports. These reports allow you to track the amount of disinfection byproducts and other contaminants in your drinking water supply. Contact your local water utility to find out when your next annual report will be released, or to review past versions.
And no matter where you live, you can always send a sample of your water to a qualified laboratory to be tested for contaminants. Either way, knowing exactly what’s in your water, and then taking the steps to make it as pure as possible, will give you peace of mind that your family’s water is healthy and safe.