Which of these contaminants requires specific testing as mandated by the SDWA?

The Safe Drinking Water Act (SDWA) mandates specific testing for various contaminants to ensure the safety of drinking water supplied to the public. Pathogenic viruses, heavy metals, and disinfection by-products are all considered significant health risks and are therefore subject to regulatory testing under the SDWA.

Pathogenic viruses, such as norovirus and hepatitis A, can pose serious health hazards, making their detection critical in preventing waterborne diseases. Heavy metals, including lead and mercury, can accumulate in the human body and cause various health issues, necessitating vigilant testing. Disinfection by-products, which can form during the water treatment process when disinfectants react with natural organic matter, have been linked to potential long-term health effects and are closely monitored.

Given that each of these contaminants poses unique risks that regulatory authorities aim to mitigate, comprehensive testing is required for all of them under SDWA guidelines. Therefore, the correct option encompasses all these contaminants, highlighting the importance of broad testing protocols to protect public health.