Epichlorohydrin

(endorsed 1996)

Guideline

Based on health considerations, the concentration of epichlorohydrin in drinking water should not exceed 0.0005 mg/L.

General description

Epichlorohydrin is used in the manufacture of glycerine and unmodified epoxy resins, including resins used in water treatment (polyelectrolytes). The United States Environmental Protection Agency has proposed that the maximum residual epichlorohydrin content in flocculating agent shall not exceed 0.01% which, at maximum resin usage rates of 20 mg/L, would lead to an epichlorohydrin concentration in drinking water of less than 0.002 mg/L. No monitoring of epichlorohydrin concentrations in drinking water has been reported. Epichlorohydrin hydrolyses in water and this can cause difficulties in detection.

Typical values in Australian drinking water

Epichlorohydrin has not been found in Australian drinking waters. It is included here to provide guidance in the unlikely event of contamination, and because it has been detected occasionally in drinking water supplies overseas.

Treatment of drinking water

No published reports are available on water treatment procedures for the removal of epichlorohydrin. Aeration is unlikely to be successful.

Measurement

Epichlorohydrin can be determined using gas chromatography with electron capture detection (Pesselman and Feit 1988). The limit of determination is approximately 0.05 mg/L.

Health considerations

In laboratory animals epichlorohydrin is rapidly absorbed after ingestion, inhalation and skin contact, and is distributed to the liver, kidneys and pancreas.

An extensive review and summary of the human and animal toxicity data for epichlorohydrin is available (IPCS 1984).

In humans, skin contact with high concentrations can cause initial redness, itching, or a burning sensation. The initial effects of inhalation are similar, and can be followed by vomiting and severe headache. Long-term exposure can cause kidney and liver damage. Epichlorohydrin has been reported to increase chromosome damage in lymphocytes, and decrease blood cell counts in occupationally exposed workers.

A long-term study where male rats were given epichlorohydrin in their drinking water for 81 weeks reported a decrease in leucocytes and an increase in the incidence of fore-stomach tumours from a dose of 39 mg/kg body weight per day and fore-stomach hyperplasia from 18 mg/kg body weight per day. A 2-year gavage study in rats, using doses of 2 and 10 mg/kg body weight per day, also reported induction of fore-stomach carcinomas. Inhalation studies in rats have reported the appearance of nasal cavity carcinomas.

Epichlorohydrin has been shown to be genotoxic both in vitro and in vivo. It is an alkylating agent and a direct-acting mutagen.

The International Agency for Research on Cancer has concluded that epichlorohydrin is probably carcinogenic to humans (Group 2A, insufficient evidence in humans, sufficient evidence in animals, and other supportive data) (IARC 1987).

Derivation of guideline

The assessment of the toxicological data for epichlorohydrin by the World Health Organization (WHO) has been used without review. The guideline value of 0.0005 mg/L was determined as follows:

$$\text{ 0.0005 mg/L } = \dfrac{\text{ 2 mg/kg body weight per day x 70 kg x 0.1 }}{\text{ 2 L/day x 10,000 }} \times \dfrac{\text{ 5 }}{\text{ 7 }}$$

where:

• 2 mg/kg body weight per day is the lowest effect level based on a 2-year gavage study using rats (Wester et al. 1985).

• 70 kg is the average weight of an adult.

• 0.1 is the proportion of total daily intake attributable to the consumption of water.

• 2 L/day is the average amount of water consumed by an adult.

• 10,000 is the safety factor in using the results of an animal study as a basis for human exposure (10 for interspecies variations, 10 for intraspecies variations, 10 because a lowest effect level was used instead of a no-effect level, and 10 for carcinogenic effects).

• 5/7 is used to convert data based on a 5 day per week feeding study to a 7-day week equivalent.

Although epichlorohydrin is a genotoxic carcinogen, the use of a linear multistage model for estimating cancer risk was considered inappropriate because tumours are seen only at the site of administration where epichlorohydrin is highly irritating.

The limit of determination is approximately 0.05 mg/L; however, concentrations in drinking water can be controlled by product specification.

The WHO guideline value of 0.0004 mg/L was based on an adult body weight of 60 kg. The difference in guideline values is not significant.

References

IARC (International Agency for Research on Cancer) (1987). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Overall Evaluations of Carcinogenicity. An updating of IARC monographs volumes 1 to 42. World Health Organization, IARC, Supplement 7.

IPCS (International Programme on Chemical Safety) (1984). Epichlorohydrin. Environmental Health Criteria, 33. World Health Organization, IPCS.

Pesselman RL, Feit MJ (1988). Determination of residual epichlorohydrin and 3-chloropropanediol in water by gas chromatography with electron capture detection. Journal of Chromatography, 439:488–542.

Wester PW, Van Der Heijden CA, Bisschop A, Van Esch GJ (1985). Carcinogenicity study with epichlorohydrin (CEP) by gavage in rats. Toxicology, 36:325–339.