EWG's Tap Water Database — 2019 UPDATE


Heptachlor epoxide

Marine Corps Base Hawaii

Heptachlor epoxide is a breakdown product of heptachlor, a highly toxic and carcinogenic pesticide banned in the U.S. since the 1980s.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.00102 ppb868ND - 0.0120 ppb
20130.000509 ppb2328ND - 0.0260 ppb
20140.000771 ppb24410ND - 0.0280 ppb
20150.00123 ppb263ND - 0.0110 ppb
20160.00233 ppb243ND - 0.0270 ppb
20170.000382 ppb1103ND - 0.0170 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.006 ppb

The EWG Health Guideline of 0.006 ppb for heptachlor epoxide 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) 0.2 ppb

The legal limit for heptachlor epoxide, established in 1991, was based on analytical detection limits at the time that the standard was set. This limit may not fully protect against the risk of cancer.

ppb = parts per billion

All test results

Date Lab ID Result