National Drinking Water Database
Carbon tetrachloride in Maryland
Carbon tetrachloride is an industrial solvent and refrigerant released as a pollutant from various chemical plants and the petroleum refining industry. [read more]
Carbon tetrachloride has been used as an industrial solvent, dry cleaning ingredient (discontinued), fire extinguishing chemical and as a chemical intermediate used in refrigerants (Freon 11 and 12) (California Environmental Protection Agency 2000b, National Toxicology Program (NTP) 2002a). Carbon tetrachloride is no longer permitted in products intended for home use in the U.S. (NTP 2002a). The Montreal Protocol on Substances that Deplete the Ozone Layer (1987) established a timetable for the phase-out of the production and consumption of carbon tetrachloride world-wide (World Health Organization (WHO) 2004a).
Carbon tetrachloride contamination in the environment is primarily due to air and water releases from petroleum refining industry, chemical plants and other industrial manufacturing activities such as production of used plastics, resins, fluorocarbons, agricultural chemicals and aerosol propellants (U.S. Environmental Protection Agency (USEPA) 2002e). Carbon tetrachloride does not break down easily in the environment and may remain in groundwater for years (California Environmental Protection Agency 2000b; WHO 2004a). Carbon tetrachloride has been detected in at least 425 of the 1,662 hazardous waste sites identified by the Environmental Protection Agency (EPA) across the U.S. (Agency for Toxic Substances and Disease Registry (ATSDR) 2005d).
In people, carbon tetrachloride causes nausea, vomiting, central nervous system depression (including decreased breathing), irregular heart rate, liver damage and kidney damage. People with diabetes may be especially vulnerable to carbon tetrachloride exposure (ATSDR 2005d).
Carbon tetrachloride is classified as "reasonably anticipated to be a human carcinogen" by the National Toxicology Program (NTP) and a "probable human carcinogen" by EPA (NTP 2002a, USEPA 2002a). In rats or mice, it causes tumors of the liver, mammary gland (breast) (NTP 2002a) and thyroid (California Environmental Protection Agency 2000b). Carbon tetrachloride may cause genetic damage because some is metabolized in the body to a reactive chemical that binds to DNA (California Environmental Protection Agency 2000b). Tissues damaged by carbon tetrachloride in laboratory animals include the brain, liver, kidney and testes. Other studies show decreased fertility and impaired immune response. Exposure during pregnancy can cause death to the embryo or fetus and decreased growth.
Carbon tetrachloride can pass across the placenta, exposing the fetus during gestational development (Dowty 1976). Several studies reported that maternal exposure to carbon tetrachloride in drinking water might be related to certain birth defects, such as low birthweight and small size at birth (ATSDR 2005d). One study linked levels of carbon tetrachloride in drinking water greater than one part per billion (ppb), five times less than EPA's MCL of five ppb, with increased risk of low birth weight, central nervous system defects and defects of the neural tube (Bove 1995; California Environmental Protection Agency 2000b). In 2000, the California Environmental Protection Agency established a Public Health Goal (PHG) for carbon tetrachloride in drinking water of 0.1 ppb, fifty times lower than the EPA MCL of five ppb.
The Most Polluted Communities in Maryland
2 water utilities reported detecting Carbon tetrachloride in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies
Ranked by highest average Carbon tetrachloride level
|Rank||System||Population Served||Positive test results of total reported tests||Average Level|
|1||Town of Mount Airy|
Mount Airy, MD
|8,631||4 of 7||0.96 ppb|
(0 to 2.6 ppb)
|2||City of Taneytown|
|6,750||1 of 11||0.05 ppb|
(0 to 0.57 ppb)
Health Based Limits for Carbon tetrachloride
|Maximum Contaminant Limit Goal (MCLG)||A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.||0 ppb|
|California Public Health Goals||Defined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.||0.1 ppb|
|EPA Human Health Water Quality Criteria||Water quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.||0.23 ppb|
|One in one million (10-6) Cancer Risk||The concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.||0.3 ppb|
|Maximum Contaminant Limit (MCL)||The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.||5 ppb|
|One in ten thousand (10-4) Cancer Risk||The concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.||30 ppb|
|Drinking Water Equivalent Level||A lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.||30 ppb|
|Children's health-based limit for 10-day exposure||Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.||200 ppb|
|Children's health-based limit for 1-day exposure||Concentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.||4000 ppb|
Violation Summary for Carbon tetrachloride in Maryland
Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in Maryland since 2004
|Violation Type||Number of Violations|
|Failure to monitor regularly||1|