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EWG's Tap Water Database — 2019 UPDATE

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Perchlorate

Holliston Water Department

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.

 

39

Samples

0

Samples exceeding legal limit (MCL)

1

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20120.143 ppb32ND - 0.260 ppb
2013ND30ND
20140.221 ppb105ND - 1.10 ppb
20150.105 ppb129ND - 0.258 ppb
20160.156 ppb770.0420 ppb - 0.307 ppb
2017ND40ND

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 Result
2012-04-230.170 ppb
2012-09-120.260 ppb
2012-09-19ND
2013-09-25ND
2013-09-25ND
2013-09-25ND
2014-05-13ND
2014-05-13ND
2014-09-090.110 ppb
2014-09-09ND
2014-09-09ND
2014-09-161.10 ppb
2014-10-200.0250 ppb
2014-10-200.548 ppb
2014-11-10ND
2014-11-100.424 ppb
2015-03-170.131 ppb
2015-03-17ND
2015-05-120.195 ppb
2015-05-12ND
2015-08-040.258 ppb
2015-08-040.143 ppb
2015-08-040.0230 ppb
2015-08-110.206 ppb
2015-08-11ND
2015-09-150.118 ppb
2015-09-150.0670 ppb
2015-12-220.119 ppb
2016-03-220.110 ppb
2016-08-010.174 ppb
2016-08-020.0610 ppb
2016-08-020.307 ppb
2016-08-020.0420 ppb
2016-08-020.160 ppb
2016-08-020.237 ppb
2017-08-30ND
2017-08-30ND
2017-08-30ND
2017-08-30ND