Thallium
Block Island Water Company
Thalium is a naturally occurring metal released into the environment from metal smelting and coal burning. Exposure to too much thalium can cause hair loss, liver damage, reduced sperm motility and nervous system impairment.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | 0.400 ppb | 3 | 1 | ND - 1.20 ppb |
| 2015 | ND | 5 | 0 | ND |
| 2016 | ND | 2 | 0 | ND |
| 2017 | ND | 4 | 0 | ND |
| 2018 | 0.0750 ppb | 4 | 1 | ND - 0.300 ppb |
| 2019 | ND | 2 | 0 | ND |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 0.1 ppb
The EWG Health Guideline of 0.1 ppb for thallium 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 harm to internal organs.
EPA Maximum Contaminant
Level (MCL) 2 ppb
The legal limit for thallium, established in 1992, was based on analytical detection limits at the time that the standard was set.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2014-04-09 | 1404248-01I | ND |
| 2014-04-09 | 1404248-02I | ND |
| 2014-09-10 | 1409222-01_IOC | 1.20 ppb |
| 2015-05-13 | 1505347-02I | ND |
| 2015-05-13 | 1505347-04I | ND |
| 2015-05-13 | 1505347-03I | ND |
| 2015-05-13 | 1505347-05I | ND |
| 2015-05-13 | 1505347-06I | ND |
| 2016-04-20 | 1604606-06I | ND |
| 2016-04-20 | 1604606-05I | ND |
| 2017-04-06 | 1704183-03I | ND |
| 2017-04-06 | 1704183-04I | ND |
| 2017-04-06 | 1704183-05I | ND |
| 2017-06-27 | 1706736-01_IOC | ND |
| 2018-04-11 | 1804353-01I | ND |
| 2018-04-11 | 1804357-01I | ND |
| 2018-04-11 | 1804350-01I | 0.300 ppb |
| 2018-04-11 | 1804351-01I | ND |
| 2019-04-10 | 1904-06459-002 | ND |
| 2019-04-10 | 1904-06459-001 | ND |