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National Drinking Water Database


1,4-Dioxane in California


1,4-Dioxane is a stabilizing chemical in industrial solvents and an emerging groundwater pollutant from solvent recycling and plastic manufacturing; it is a probable human carcinogen. [read more]

The Most Polluted Communities in California

16 water utilities reported detecting 1,4-Dioxane in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average 1,4-Dioxane level

RankSystem Population Served Positive test results of total reported tests Average Level
(Range)
1Santa Monica-City, Water Division
Santa Monica, CA
84,18414 of 164.8 ppb
(0 to 7.3 ppb)
2California Water Service Co. - Ela
Montebello, CA
151,04253 of 604.04 ppb
(0 to 8 ppb)
3Park WC - Bellflower-Norwalk
Downey, CA
71,00012 of 123.88 ppb
(3.05 to 5.59 ppb)
4Tract 349 Mutual Water Co.
Cudahy, CA
7,50014 of 152.42 ppb
(0 to 4.7 ppb)
5Gswc - Norwalk
Santa Fe Springs, CA
31,3203 of 31.82 ppb
(1.6 to 2.17 ppb)
6South Gate-City, Water Dept.
South Gate, CA
82,55012 of 141.44 ppb
(0 to 3.7 ppb)
7Gswc - Bell, Bell Gardens
Santa Fe Springs, CA
24,3216 of 90.78 ppb
(0 to 2.1 ppb)
8Gswc-South San Gabriel
San Dimas, CA
15,59315 of 290.74 ppb
(0 to 2 ppb)
9Monterey Park-City, Water Dept.
Monterey Park, CA
57,0002 of 70.49 ppb
(0 to 1.7 ppb)
10Suburban Water Systems-Whittier
Covina, CA
58,08949 of 840.41 ppb
(0 to 1.4 ppb)

Health Based Limits for 1,4-Dioxane

StandardDescriptionLevel
One in one million (10-6) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.3 ppb
One in ten thousand (10-4) Cancer RiskThe concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.300 ppb
Children's health-based limit for 10-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.400 ppb
Children's health-based limit for 1-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.4000 ppb

Violation Summary for 1,4-Dioxane in California

There are no violations reported for this contaminant in California