Is Tetrachloroethylene safe in drinking water?

Long-term exposure to tetrachloroethylene in drinking water above the Maximum Contaminant Level (MCL) of 0.005 mg/L (5 ppb) is associated with an increased risk of cancer, including bladder cancer, multiple myeloma, and non-Hodgkin's lymphoma in humans, and liver, kidney, and blood system cancers in animals.

Why here

Tetrachloroethylene can contaminate drinking water through improper disposal, spills, or leaching from vinyl-lined pipes in water distribution systems, leading to ingestion.

What would have to be true

Ingestion of drinking water containing tetrachloroethylene at concentrations above the EPA MCL of 0.005 mg/L (5 ppb) over many years.

The other side

The U.S. EPA has set a Maximum Contaminant Level Goal (MCLG) of zero for tetrachloroethylene, indicating no adverse health effects are expected at this level, but the enforceable MCL is 0.005 mg/L (5 ppb) due to treatment feasibility.

The International Agency for Research on Cancer (IARC) classifies tetrachloroethylene as 'probably carcinogenic to humans' (Group 2A), based on limited evidence in humans and sufficient evidence in experimental animals.

Why here

This classification applies to human exposure, including through contaminated drinking water.

What would have to be true

Exposure to tetrachloroethylene from various sources, including drinking water.

Long-term exposure to tetrachloroethylene in drinking water above the MCL can cause liver and kidney problems, and detrimental effects to the central nervous system.

Why here

Ingestion of contaminated drinking water leads to systemic exposure.

What would have to be true

Ingestion of drinking water containing tetrachloroethylene at concentrations above the EPA MCL of 0.005 mg/L (5 ppb) over many years.

Studies in Massachusetts have suggested an association between exposure to tetrachloroethylene from public drinking water and an increased risk of lung and colon-rectum cancer, as well as a small to moderate increased risk of breast cancer among women with the highest exposure levels.

Why here

Tetrachloroethylene leached from vinyl-lined water distribution pipes into public drinking water, leading to chronic ingestion by residents.

What would have to be true

Ingestion of public drinking water contaminated with tetrachloroethylene, particularly at higher exposure levels (e.g., above the 75th and 90th percentiles in studies), over long periods.

The other side

While these studies suggest associations, the IARC review noted that in four out of five studies of people exposed to drinking water contaminated with tetrachloroethylene, no consistent pattern of risk for any specific cancers was observed, and confounding cannot be excluded.

Studies have suggested that exposure to tetrachloroethylene in drinking water may be harmful to unborn children and could increase the numbers of babies with birth defects such as heart, oral cleft, or neural defects, though these studies were not large enough to definitively confirm causation.

Why here

Ingestion of contaminated drinking water by pregnant individuals leads to fetal exposure.

What would have to be true

Ingestion of drinking water containing tetrachloroethylene, particularly during pregnancy.

The other side

It is not known whether children are more susceptible than adults to the effects of tetrachloroethylene, and more studies are needed to clarify the link between tetrachloroethylene and birth defects.

Tetrachloroethylene is classified as probably carcinogenic to humans (Group 2A) by the International Agency for Research on Cancer (IARC), and as likely to be carcinogenic to humans by the U.S. Environmental Protection Agency (EPA), based on suggestive evidence in human studies and clear evidence in animal studies.

Why here

Tetrachloroethylene is a volatile organic compound, and inhalation is a primary route of exposure, particularly in occupational settings (e.g., dry cleaning) and from contaminated indoor air, leading to systemic absorption.

What would have to be true

Chronic inhalation exposure, such as in occupational settings where dry cleaning workers have been exposed to mean levels of 59 ppm, with some machine operators exposed to >100 ppm.

Acute inhalation of high levels of tetrachloroethylene can cause central nervous system (CNS) depression, leading to symptoms such as dizziness, drowsiness, headache, incoordination, confusion, nausea, and unconsciousness, with very high levels potentially causing death. Chronic exposure to lower levels can result in changes in mood, memory, attention, reaction time, and vision.

Why here

Tetrachloroethylene is readily absorbed through the lungs and, due to its lipophilic nature, distributes to the brain, where it interacts with neural membranes to exert its anesthetic and neurotoxic effects.

What would have to be true

Acute exposure to concentrations above 1,490 mg/m3 (approximately 219 ppm) for short durations (e.g., 1 hour) can cause dizziness and drowsiness. Chronic occupational exposure to levels as low as 7.3 ppm has been associated with color vision impairment.

Acute inhalation exposure to tetrachloroethylene vapor can cause irritation to the upper respiratory tract, eyes, and mucous membranes.

Why here

The volatile nature of tetrachloroethylene allows it to be present in the air and directly contact respiratory and ocular tissues upon inhalation.

What would have to be true

Mild nasal irritation has been reported at 690 mg/m3 (approximately 101 ppm) for 7 hours or 1,500 mg/m3 (approximately 220 ppm) for 1 hour. Exposures of 6,400 to 8,200 mg/m3 have resulted in immediate and severe respiratory tract irritation.

Some studies suggest a very limited association between tetrachloroethylene exposure and disruption of the menstrual cycle in humans.

Why here

As a systemic toxicant absorbed via inhalation, there is a theoretical potential for interference with endocrine pathways, though direct and conclusive evidence is scarce.

What would have to be true

Occupational exposure to tetrachloroethylene.