Arsenic case study - should drinking water standards be set at the federal level or at a finer scale?

The drinking water standards for arsenic should be set at a finer scale such as the state level or lower. This is because arsenic concentrations vary greatly from region to region and even state to state. Setting one single national standard would not be accurate or effective enough to protect public health uniformly throughout the entire country. Additionally, in some cases, individual data on arsenic levels or even water samples for testing may be unavailable at the federal level, making it difficult to accurately set a single federal standard. Regional or state-specific standards based on local data may be more effective at protecting drinking water from arsenic contamination in the long run.