EWG's Tap Water Database — 2021 UPDATE



Thomas Hill PWSD 1

p-Dichlorobenzene is a carcinogenic insecticide used in mothballs, and added to deodorant blocks made for trash cans and toilets. Long-term exposure can cause liver damage and kidney problems.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20160.730 ppb110.730 ppb
20171.36 ppb220.790 ppb - 1.92 ppb
20180.640 ppb110.640 ppb
20190.228 ppb41ND - 0.910 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 6 ppb

The EWG Health Guideline of 6 ppb for p-dichlorobenzene was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL) 75 ppb

The legal limit for p-dichlorobenzene, established in 1987, was based on toxicity studies conducted in laboratory animals in the 1980s. This limit may not fully protect against the risk of cancer due to p-dichlorobenzene exposure.

ppb = parts per billion

All test results

Date Lab ID Result