1,4-Dioxane
City of Napa
1,4-Dioxane is a solvent classified by the EPA as a likely human carcinogen. It contaminates groundwater in many states due to industrial wastewater discharges, plastic manufacturing runoff and landfill runoff. Read More.
Animal studies show that 1,4-dioxane can target the liver, kidneys and respiratory system, and that prenatal exposure can harm the developing fetus. The State of California has set a Public Heatlh Goal of no more than 1 part per billion of 1,4-dioxane in drinking water. The state of Massachusetts sets a legal limit of 0.3 ppb, and New Hampshire's limit is 3 parts per billion. There is no national drinking water standard for this contaminant.
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 | ND | 6 | 0 | ND |
| 2014 | ND | 3 | 0 | ND |
| 2015 | ND | 3 | 0 | ND |
| 2016 | ND | 2 | 0 | ND |
| 2017 | ND | 3 | 0 | ND |
| 2018 | ND | 2 | 0 | ND |
| 2019 | ND | 2 | 0 | ND |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 0.35 ppb
The EWG Health Guideline of 0.35 ppb for 1,4-dioxane was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2013-02-25 | 1302776-001A | ND |
| 2013-04-03 | 1304110-001D | ND |
| 2013-07-10 | 1307416-001D | ND |
| 2013-07-10 | 1307419-001D | ND |
| 2013-10-03 | 1310111-001D | ND |
| 2013-10-03 | 1310113-001D | ND |
| 2014-07-09 | 1233-007-0925 | ND |
| 2014-07-09 | 1233-006-1245 | ND |
| 2014-07-09 | 1233-005-1145 | ND |
| 2015-07-21 | 1233-005-1120 | ND |
| 2015-07-21 | 1233-007-0940 | ND |
| 2015-07-21 | 1233-006-1415 | ND |
| 2016-07-27 | 1233-007-1245 | ND |
| 2016-07-27 | 1233-006-1545 | ND |
| 2017-07-20 | 1233-007-1050 | ND |
| 2017-07-20 | 1233-006-1330 | ND |
| 2017-09-13 | 1233-005-0840 | ND |
| 2018-07-11 | 1233-007-1200 | ND |
| 2018-07-11 | 1233-006-1015 | ND |
| 2019-07-10 | 1233-007-0830 | ND |
| 2019-07-10 | 1233-006-1200 | ND |