What harmful by-product is associated with the chlorination of water?

The correct response highlights the presence of trihalomethanes (THMs) as a harmful by-product formed during the chlorination process of water. When chlorine is used as a disinfectant, it reacts with organic matter naturally present in water, leading to the formation of THMs. These compounds can have health implications, including an increased risk of certain cancers and issues related to liver and kidney function when individuals are exposed to them over an extended period.

Understanding the formation of THMs is crucial for water quality analysts because it underscores the balance needed between effective disinfection and minimizing harmful by-products. Recognizing this can aid in developing treatment strategies that reduce the formation of THMs while still ensuring the water is safe for consumption.

In contrast, lead, sulfate, and nitrite are not direct by-products of chlorination. Lead typically originates from plumbing systems and the corrosion of pipes, sulfate can come from various sources including industrial processes and natural mineral dissolution, and nitrite is often associated with agricultural runoff and nitrogen contamination in water sources. These substances, while relevant pollutants or concerns in water quality, do not share the same direct relationship to chlorination as THMs do.