Styrene
San Francisco City Water System
Styrene is a volatile cancer-causing chemical used for manufacturing Styrofoam (polystyrene) and other plastics. Releases from industrial production sites and hazardous waste landfills cause styrene contamination in drinking water. Read More.
In addition to increasing the risk of cancer, styrene can also damage the liver and the nervous system. California set a public health goal for styrene in drinking water at 0.5 parts per billion. The federal Maximum Contaminant Level (MCL) allows up to 100 parts per billion of styrene in water, which is 200 times more than the California recommended level.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2013 | N/A | 0 | 0 | N/A |
| 2014 | N/A | 0 | 0 | N/A |
| 2015 | N/A | 0 | 0 | N/A |
| 2016 | ND | 1 | 0 | ND |
| 2017 | N/A | 0 | 0 | N/A |
| 2018 | ND | 17 | 0 | ND |
| 2019 | ND | 4 | 0 | ND |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 0.5 ppb
The EWG Health Guideline of 0.5 ppb for styrene 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 cancer.
EPA Maximum Contaminant
Level (MCL) 100 ppb
The legal limit for styrene, established in 1991, was based on a toxicity study in laboratory animals conducted in the 1970s. This limit may not fully protect against the risk of cancer due to styrene exposure.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2016-06-14 | 9553-001-0920 | ND |
| 2018-01-11 | 9553-007-1115 | ND |
| 2018-03-06 | 9590-004-1031 | ND |
| 2018-03-08 | 9590-006-0925 | ND |
| 2018-04-17 | 9590-007-1055 | ND |
| 2018-04-30 | 9590-008-1013 | ND |
| 2018-06-12 | 9590-008-0930 | ND |
| 2018-06-12 | 9590-004-1058 | ND |
| 2018-07-17 | 9590-007-0519 | ND |
| 2018-07-26 | 9553-006-0838 | ND |
| 2018-09-12 | 9590-004-0944 | ND |
| 2018-09-25 | 9553-006-0930 | ND |
| 2018-09-25 | 9553-004-0910 | ND |
| 2018-09-25 | 9553-008-0950 | ND |
| 2018-10-17 | 9553-007-0730 | ND |
| 2018-12-11 | 9553-004-0845 | ND |
| 2018-12-11 | 9553-006-0915 | ND |
| 2018-12-11 | 9553-008-1045 | ND |
| 2019-06-17 | 9553-008-1106 | ND |
| 2019-06-17 | 9553-007-0905 | ND |
| 2019-06-17 | 9553-006-1206 | ND |
| 2019-06-17 | 9553-004-0956 | ND |