Phosphate ester flame retardants are human-made chemicals added to consumer and industrial products for the purpose of reducing flammability.

Phosphate ester flame retardants are composed of a group of chemicals with similar properties but slightly different structures.

Phosphate esters are typically liquids at room temperature; however, some are solids.

Phosphate esters are flame retardants, plasticizers, hydraulic fluids, solvents, extraction agents, antifoam agents, and coatings for electronic devices.

Phosphate ester flame retardants are released to the environment from industrial sources and disposal of consumer products containing flame retardants.

• air

Phosphate ester flame retardants can change chemical composition in the environment.

There is no specific information available for the eight phosphate ester flame retardants discussed in this document; however, in general, these compounds are degraded by chemical reactions in the air. If they attach themselves to particles, they can settle out onto the ground.

• Water and soil

Generally, most phosphate esters are poorly soluble in water and adsorb strongly to soils. These compounds are commonly detected in water due to their widespread use in commercial products. Phosphate esters are subject to biodegradation in aquatic and terrestrial environments.

Humans can be exposed by a combination of oral, inhalation, and dermal routes.

Ingesting contaminated food: Most foods have been found to contain trace amounts of phosphate ester flame retardants due to their wide use in plastics and presence in the environment.

Breathing contaminated outdoor air: Hydraulic fluid is the primary source of phosphate esters in outdoor air.

Breathing contaminated indoor air: Indoor air can contain phosphate ester flame retardants from certain plastics, adhesives, foams, or electronics.

Drinking water contaminated with phosphate esters due to leaching from plastics or industrial waste water discharge.

By skin contact with contaminated soil: Hydraulic fluid spills or industrial waste water used for agriculture can result in the presence of phosphate esters in soil.

Young children may be at a higher risk of exposure since they are more likely to put phosphate ester flame retardant treated materials in their mouths.

• Humans

There is virtually no information about the entrance of these substances into the body. However, TDCP had been found in human tissues and body fluids, so we know that this substance can enter the body possibly by inhaling aerosols or dusts or ingesting contaminated food or water. Adverse health effects seen in humans after exposure to TCP indicate that this substance can enter the body and pass into the bloodstream.

• Animals

Oral - Studies found that TDCP, TCEP, TCP, and TnBP can easily pass from the stomach and intestines into the blood stream.

Dermal - Less amounts entered the body through the skin of rats and only very small amounts through the skin of pigs.

Leave your body

• Humans

There is no information on how these chemicals leave your body, but based on studies in animals, phosphate ester flame retardants may be broken down in the body and the breakdown product may be eliminated in the urine. However, there are no studies in humans to prove that this actually happens.

• Animals

Neither phosphate ester flame retardants nor their breakdown products seemed to accumulate in the body. Most breakdown products were eliminated in the urine in 2-3 days.

Long-term exposure of workers to TDCP, TCP, or TPP was not associated with adverse health effects. No information was available regarding exposure to other phosphate ester flame retardants.

Almost no information is available regarding health effects in members of the general population exposed to the phosphate ester flame retardants discussed in this profile. However, accidental ingestion of a component of TCP, tri-o-cresyl phosphate, has caused adverse effects on the nervous system.

There have been a few cases of allergic reactions to consumer products that contain TPP, but a study that examined several hundred people exposed to plastics and glues that contained TPP or TCP did not find any allergic reactions.

One way to learn about the effects of phosphate ester flame retardants is to see how they affect test animals. Almost all studies in animals have administered these substances orally and generally at levels much higher than what can be expected from environmental exposures.

TCEP given to rats for 16 weeks or longer caused brain lesions. When given for 2 years, it also caused lesions in the kidneys. TCEP also decreased the fertility of mice that were exposed for 18 weeks before mating.

TnBP induced lesions in the urinary bladder of rats when given for 10 weeks or longer.

TBEP caused liver lesions in rats after the rats ate food that contained TBEP for 18 weeks.

A study showed that rats that ate food containing TCP for 2 years developed lesions in the ovary and adrenal gland and male mice developed liver lesions. TCP also decreased fertility in rats and mice.

Rats that ate food containing TDCP for 2 years developed lesions in the kidneys and liver.

The few studies that examined the effects of TPP, TiBP, and TCPP in animals did not report significant adverse health effects.

There is not enough information available to determine with certainty whether or not phosphate ester flame retardants produce cancer in humans.

Studies of workers employed in the manufacture of TDCP and TCP did not find significant associations between exposure and cancer. No information was available regarding the carcinogenic potential of the other phosphate esters to humans.

Rats that received oral doses of TCEP for 2 years developed kidney tumors. Feeding mice a diet that contained TCEP for 18 months induced tumors in the kidney, liver, and stomach, and also induced leukemia. Long-term administration of TnBP to rats and mice induced tumors in the urinary bladder and the liver, respectively. Feeding rats with a diet that contained TDCP for 2 years produced tumors in the liver, kidneys, testes, and adrenal gland.

Neither the EPA nor the Department of Health and Human Services (DHHS) has classified the carcinogenic potential of the phosphate esters discussed in this profile. The International Agency for Research on Cancer (IARC) determined that TCEP is not classifiable as to its carcinogenicity to humans.

There are no studies that examined the health effects of the phosphate ester flame retardants discussed in this profile on pregnant women or on their embryo or fetus.

There are no studies that examined the health effects in children of the phosphate ester flame retardants discussed in this document.

In general, exposure of rodents during gestation to TCEP, TnBP, TBEP, TDCP, TPP, or TCPP did not result in adverse effects to the fetuses or newborn animals.

However, continuous exposure of two generations of mice to TCEP reduced the number of male pups born alive in the third generation. A similar study with TnBP in rats found that pups born to exposed rats had lower body weight during the first weeks of life than pups born to untreated rats. Studies in rats and mice also found that exposure to TCP before and during pregnancy can increase the number of pups born dead.

There is no information regarding transfer of phosphate ester flame retardants to the fetus across the placenta in pregnant women.

No studies have been conducted to determine whether phosphate ester flame retardants can be detected in human breast milk from women exposed at work or from the general population.

Avoid food that is generally high in phosphate ester content as indicated by the current market basket for the U.S. Total Diet study.

Avoid installation or use of materials that are known to contain phosphate ester-based flame retardants in indoor environments to minimize exposure to them via air and particulate matter.

Phosphate ester flame retardants can be measured in blood and urine, but this is not a routine test that can be performed in a doctor's office. You should, however, see a physician if you believe that you have been exposed to high levels of these substances. No studies have been conducted to measure these chemicals in blood samples from groups of people representative of the U.S. general population.

The presence of phosphate ester flame retardants in your blood may indicate that you have been exposed to these substances and some amount entered your bloodstream.

The presence of phosphate ester flame retardants in your blood does not necessarily indicate that adverse health effects will occur. Additional studies are needed to help to determine the health effects associated with exposure to these substances.

OSHA set a legal limit of 3 and 5 mg/m³ for TPP and TnBP, respectively, in air averaged over an 8-hour work day.

The EPA has permitted TnBP, TBEP, and TPP for use in nonfood pesticide products.