Selenium
EPA Designation Regulated
EPA Classification Inorganic Chemicals
EPA Levels 1,2 0.05 MCLG (mg/L)
0.05 MCLG (mg/L)
Alternative Names none
Sources Discharge from petroleum refineries; erosion of natural deposits; discharge from mines
Selenium is a naturally occurring element that contaminates water due to mining or petrolum refining, fly-ash from coal-burning power plants, and irrigation of arid farmland soils high in selenium.

Overview

Selenium is a metal found in natural deposits such as ores containing other elements.

Uses

The greatest use of selenium compounds is in electronic and photocopier components, but they are also widely used in glass, pigments, rubber, metal alloys, textiles, petroleum, medical therapeutic agents, and photographic emulsions.

Health Effects

Some people who drink water containing selenium well in excess of the maximum contaminant level (MCL) for many years could experience hair or fingernail losses, numbness in fingers or toes, or problems with their circulation.

EPA Data Source: Selenium

EPA Definitions:

1Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.

Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.

Maximum Residual Disinfectant Level Goal (MRDLG) - The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

(TT) Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.

Maximum Residual Disinfectant Level (MRDL) - The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

2 Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.