Water Disinfectants & disinfectant by-products

6. Conclusions

Water disinfection is, without question, one of the most important barriers to waterborne disease in most parts of the world. As a consequence disinfection should never be compromised in attempting to control disinfection by-products (DBPs). The risks of illness and death from germs in drinking water is very much greater than the risks from disinfectants and disinfection by-products. However, actions have been taken to reduce the levels of DBPs.

Chlorine and alternative chemical disinfectants (ozone, chlorine dioxide and chloramines) all lead to the formation of disinfectant by-products (DBPs). Currently, the DBPs of most concern include trihalomethanes (THMs), haloacetic acids (HAAs), bromate and chlorite. The toxicology of the DBPs suggests that the likelihood of adverse effects is not significantly different between different water disinfection options.

Animal studies indicate that none of the chlorination by-products studied to date is a potent carcinogen at concentrations normally found in drinking water. There is insufficient epidemiological evidence to conclude that drinking chlorinated water causes cancers.

The results of currently published studies do not provide convincing evidence that chlorinated water or THMs cause adverse pregnancy outcomes.

Nevertheless it is prudent to take steps to minimise exposure to DBPs, where this can be achieved without compromising disinfection. Strategies should focus on eliminating organic impurities fostering DBP formation. More...