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EWG's Tap Water Database — 2019 UPDATE

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Perchlorate

City of Hollister

Perchlorate, a component of rocket fuel, occurs both naturally and as a synthetic chemical. Ingested perchlorate interferes with thyroid function. Exposure to perchlorate during pregnancy and childhood can impair cognitive development. Read More.

According to the EPA, perchlorate likely contaminates the water of more than 16 million Americans. Perchlorate interferes with iodine uptake in the thyroid, which can result in reduced thyroid hormones and an impact on metabolism, physical development and cognitive development. Children and developing fetuses are the most at risk from perchlorate contamination.

Perchlorate is the only unregulated contaminant for which the EPA has attempted to set a federal drinking water standard since 1996. However, the agency has yet to propose a draft limit for this contaminant. Perchlorate in drinking water is regulated in Arizona, California, Massachusetts, New Jersey, New York and Texas. California set a public health goal of 1 part per billion for perchlorate in 2015.

Click here to read more about perchlorate.

 

18

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012ND60ND
2013N/A00N/A
2014ND60ND
2015N/A00N/A
2016N/A00N/A
2017ND60ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 1 ppb

The EWG Health Guideline of 1 ppb for perchlorate 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 hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2012-02-291610-005-1545ND
2012-02-291610-006-1430ND
2012-02-291610-007-1440ND
2012-02-291610-009-1450ND
2012-03-011610-001-1005ND
2012-03-011610-002-1000ND
2014-06-121610-007-1250ND
2014-06-121610-006-1315ND
2014-06-121610-005-1015ND
2014-06-121610-009-1055ND
2014-06-121610-002-1145ND
2014-06-121610-001-1205ND
2017-06-011610-002-1045ND
2017-06-011610-001-1011ND
2017-06-081610-009-0949ND
2017-06-081610-007-0916ND
2017-06-081610-006-1236ND
2017-06-081610-005-1150ND