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EWG's Tap Water Database — 2019 UPDATE

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Uranium

San Pedro Canyon Subdivision - Upper

Uranium is a known human carcinogen. The federal legal limit for uranium is set at 30 micrograms per liter (corresponding to parts per billion), but utilities can also report uranium in picocuries per liter (pCi/L), which is a measure of radioactivity in water. EWG translated all uranium results to pCi/L using a conversion factor developed by the EPA. With this conversion approach, the limit of 30 ppb corresponds to 20 pCi/L. Drinking water with this much uranium would cause more than 4.6 cancer cases in a population of 100,000. California set a public health goal for uranium of 0.43 pCi/L. Read More.

Multiple forms of uranium can be detected in water, including uranium-234, uranium-235 and uranium-238. Uranium-234 is the most toxic form of uranium for human health.

 

24

Samples

0

Samples exceeding legal limit (MCL)

10

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20120.18 pCi/L41ND - 0.74 pCi/L
20130.37 pCi/L42ND - 0.74 pCi/L
20140.52 pCi/L43ND - 0.74 pCi/L
20150.54 pCi/L43ND - 0.74 pCi/L
20160.18 pCi/L41ND - 0.74 pCi/L
2017ND40ND

pCi/L = picocuries per liter

State and national drinking water standards and health guidelines

EWG Health Guideline 0.43 pCi/L

The EWG Health Guideline of 0.43 pCi/L for uranium 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. Three most common uranium isotopes are U-234, U-235 and U-238. All isotopes of uranium are radioactive, and the total radioactivity depends on the ratio of isotopes. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL) 20 pCi/L

pCi/L = picocuries per liter

All test results

Date Lab ID Result
2012-02-27AB82147ND
2012-04-18AB87473ND
2012-08-21AB994880.74 pCi/L
2012-11-28AC05753ND
2013-03-13AC13437ND
2013-06-27AC234290.74 pCi/L
2013-09-18AC306470.74 pCi/L
2013-12-10AC37437ND
2014-03-05AC456460.67 pCi/L
2014-06-03AC557780.74 pCi/L
2014-07-09AC591480.67 pCi/L
2014-12-17AC75267ND
2015-03-11AC83690ND
2015-06-03AC945070.74 pCi/L
2015-08-19AD046510.67 pCi/L
2015-12-09AD161860.74 pCi/L
2016-02-24AD25318ND
2016-05-19AD374320.74 pCi/L
2016-09-07AD48236ND
2016-11-09AD57338ND
2017-03-21AD76278ND
2017-05-02AD82081ND
2017-09-18AD96495ND
2017-11-28AE05896ND