Final answer:
Trihalomethanes (THMs) are a group of chemicals that form when chlorinated water reacts with natural organic matter. They are disinfection byproducts found in treated drinking water and have been linked to potential health risks.
Step-by-step explanation:
THM stands for Trihalomethane. Trihalomethanes are a group of chemicals that can form when chlorinated water reacts with natural organic matter, such as decaying plant material. They are commonly found in treated drinking water and are considered disinfection byproducts. The presence of THMs in water is a concern because they have been linked to potential health risks, including cancer and reproductive issues.