1,4-Dioxane
Cathedral Gardens Water District
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 |
|---|---|---|---|---|
| 2018 | 0.0149 ppb | 13 | 6 | ND - 0.0490 ppb |
| 2019 | 0.00650 ppb | 4 | 1 | ND - 0.0260 ppb |
| 2020 | 0.0106 ppb | 18 | 6 | ND - 0.0370 ppb |
| 2021 | 0.240 ppb | 14 | 7 | ND - 0.480 ppb |
| 2022 | 0.450 ppb | 32 | 10 | ND - 0.900 ppb |
| 2023 | 0.305 ppb | 33 | 10 | ND - 0.610 ppb |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
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 |
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