Highest on this list is pregnant women. Pregnant women should discuss this issue with their physicians. While deciding what to do on the household level is an individual decision, deciding what to do on the community level is a governmental decision. After much consideration our federal government has decided that the health questions surrounding TTHM are sufficient to require community water treatment plants take corrective action to achieve low TTHM levels in water. Some scientific studies have linked TTHM to increased risk of cancer .
Several studies suggest a small increase in the risk of bladder cancer and colorectal cancer.
Beyond the cancer and reproduction concerns, some investigations have found that chlorination by-products may be linked to heart, lung, kidney, liver, and central nervous system damage. Other studies have linked TTHM to reproductive problems , including miscarriage. A North Carolina study investigating the same question but found no strong relationship between TTHM and problem pregnancies. When taken in total, the cancer evidence is probably the strongest among these possible health risks. These distinctions among the specific chemical by-products of is a result of toxicological, not empidemiological studies.