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EWG's Tap Water Database — 2019 UPDATE

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Selenium

Contra Costa Water District

Selenium is an essential element in diets. But too much selenium can decrease thyroid hormone production and cause hair loss, skin lesions and brittle fingernails.

 

8

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012ND10ND
2013ND10ND
2014ND20ND
2015ND10ND
2016ND10ND
2017ND20ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 30 ppb

The EWG Health Guideline of 30 ppb for selenium 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 hair loss and nail damage.

EPA Maximum Contaminant
Level (MCL) 50 ppb

The legal limit for selenium, established in 1991, was based on human epidemiological studies of populations exposed to naturally occurring selenium in drinking water. This limit does not include any additional consideration of children’s health.

ppb = parts per billion

All test results

Date Lab ID Result
2012-07-092473-003-0800ND
2013-07-159590-003-1345ND
2014-07-079590-003-1455ND
2014-07-219590-019-1330ND
2015-07-069590-003-0815ND
2016-07-119590-003-1350ND
2017-07-109590-003-1450ND
2017-12-199590-003-1330ND