Water Disinfection Byproduct Health Effects

[Guest guest]

*From:* Conspiracy Hunter

*Date:* Sun Apr 14, 2002 3:49 am

*Subject:* Drinking Water Disinfection Byproduct Health Effects

*Disinfection Byproduct Health Effects

*September 20, 1999

http://www.epa.gov/enviro/html/icr/dbp_health.html

Since the discovery of chlorination byproducts in drinking water in

1974, numerous toxicological studies (studies on the health effects from

exposure to high dosages contaminants usually involving animals in a

lab) have been conducted. These studies have shown several _disinfection

byproducts(1)_ to be carcinogenic in laboratory animals (e.g., including

_bromate(2)_, certain _trihalomethanes(3)_ and _haloacetic acids(4)_).

Some disinfection byproducts have also been shown to cause adverse

reproductive or developmental effects in laboratory animals (e.g.,

_chlorite(5)_ and certain _trihalomethanes(6)_ and _haloacetic

acids(4)_). However, there is considerable uncertainty involved in using

the results of high-dose, toxicological studies of some byproducts

occurring in disinfected drinking water to estimate the risk to humans

from chronic exposure to low doses of these and other byproducts.

In the area of epidemiology (studies of the factors that influence

disease in human populations), a number of studies have been completed

investigating the relationship between exposure to chlorinated surface

water and cancer. Some have suggested an increased cancer risk to those

exposed to chlorinated waters while others have demonstrated none. In

issuing the _Stage 1 Disinfectants/Disinfection Byproducts Rule(7)_

based on evidence then available, EPA stated that while the agency

cannot conclude there is a causal link between exposure to chlorinated

surface water and cancer, these studies have suggested an association,

albeit small, between bladder, rectal, and colon cancer and exposure to

chlorinated surface water. There are fewer epidemiology studies

evaluating the association between exposure to disinfection byproducts

and reproductive and developmental effects. Again, some have suggested

an increased risk from exposure to disinfection byproducts while others

have shown none. There remains considerable debate in the scientific

community on the significance of these contradictory findings concerning

chlorinated water and disinfection byproducts. As with cancer, EPA

stated in its _Stage 1 Disinfectants/Disinfection Byproducts Rule_ that,

based on data then available, the agency can not conclude there is a

causal link between exposure to disinfection byproducts and reproductive

and developmental effects. In sum, EPA believes the weight-of-evidence

presented by the available epidemiological studies on chlorinated

drinking water and toxicological studies on individual disinfection

byproducts support a potential hazard concern and warrant regulatory

action at this time such as that taken in the _Stage 1

Disinfectants/Disinfection Byproducts Rule_.

An extensive research effort (_1997 Update to ORD's Strategic Plan(8)_,

_National Toxicology Program(9)_) is currently underway to better

understand the potential risks attending exposure to disinfection

byproducts. While this research is being completed, an agreement among

water suppliers, environmental groups, consumer groups, and regulatory

agencies has been reached, resulting in the publication of a _Stage 1

Disinfectants/Disinfection Byproducts Rule_ by EPA in the Federal

Register in December 1998. The participants recommended that while

additional information, especially on health effects, is needed, the

_Stage 1 Disinfectants/Disinfection Byproducts Rule_ was considered the

best course of action to reduce potential risks from disinfection

byproducts in the near term.

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tplan/page1-20.

<http://www.epa.gov/ORD/WebPubs/stratplan/page1-20.pdf>pdf

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s.nih.gov/

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