Acrylamide
(endorsed 1996)
Guideline
Based on health considerations, the concentration of acrylamide in drinking water should not exceed 0.0002 mg/L.
General description
Acrylamide occurs as a minor impurity in polyacrylamide. It may be present in drinking water through the use of polyacrylamides as flocculant aids in water treatment, and through the use of grouting agents containing polyacrylamide. Overseas studies have reported concentrations of up to a few micrograms per litre in drinking water.
When nonionic or anionic polyacrylamides are used in water treatment at a typical dose level of 1 mg/L, the maximum theoretical concentration of acrylamide has been estimated at 0.0005 mg/L, with practical concentrations 2–3 times lower. Residual levels of acrylamide from the use of cationic polyacrylamides may be higher.
Concern over the health effects of acrylamide has led some countries to introduce tight restrictions on its use for water treatment.
Polyacrylamide is used in food processing and exposure to acrylamide may also occur from this source.
Typical values in Australian drinking water
Acrylamide 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
Acrylamide can be removed from drinking water by adsorption onto granular activated carbon. It is not removed effectively by conventional water treatment or with powdered activated carbon.
Measurement
Acrylamide can be analysed using high performance liquid chromatography with ultraviolet detection (Brown and Rhead 1979). The sample is brominated to form 2,3-dibromopropionamide, which is extracted with ethyl acetate and analysed. The limit of determination is 0.0002 mg/L.
Health considerations
Acrylamide is readily absorbed following ingestion or inhalation, or through the skin, and it forms a number of metabolites. It can accumulate in nervous system tissues and blood. The results of animal studies indicate that it is largely excreted as metabolites in urine and bile. It can cross the placenta.
An extensive review and summary of the human and animal toxicity data for acrylamide is available (IPCS 1985).
Humans exposed for a short time to well water contaminated with up to 400 mg/L of acrylamide showed effects including confusion, disorientation, memory disturbances and hallucinations. They recovered fully within 4 months. Long-term occupational exposure has resulted in skin irritation, fatigue, foot weakness and sensory changes.
In animals, acrylamide is well established as a neurotoxicant. Short- and long-term effects are similar, with exposure causing paralysis in the hind limbs of cats, dogs and rats at doses from 5 mg/kg body weight per day. The animals recovered completely when short-term exposure stopped. Acrylamide can also impair reproductive organs in rats, cats and dogs at the same dose.
Animal studies indicate that acrylamide is a carcinogen. Male rats receiving low oral doses (0.5 mg/kg body weight per day) for 2 years had increased incidence of scrotal, thyroid and adrenal tumours. Female rats exposed for 18 months had increased tumours of the mammary glands, central nervous system, thyroid and uterus. Mice exposed to higher doses for 8 weeks showed an increased incidence of lung adenomas.
Several studies have reported that acrylamide is not mutagenic in bacteria, but induces gene mutations and chromosomal aberrations in mammalian cells both in vitro and in vivo.
The International Agency for Research on Cancer (IARC) has concluded that acrylamide is probably carcinogenic to humans (Group 2A, inadequate evidence in humans, sufficient evidence in experimental animals, and supporting mechanistic evidence) (IARC 1994).
Derivation of guideline
The guideline value for acrylamide of 0.0002 mg/L is based on a consideration of health effects in relation to the limit of determination for analysis using commonly available techniques.
Health-based derivations can be determined as follows:
where:
0.2 mg/kg body weight per day is the no-effect level from a 93-day drinking water study using rats (Burek et al. 1980). Longer-term studies only identify lowest effect levels, which are significantly higher than the no-effect level used in the calculation.
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.
1000 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 and 10 for a less than lifetime study). An additional factor of 10 for carcinogenicity was not applied as tumours occur at doses above those that cause neurotoxic effects. The use of this safety factor was recommended by the NHMRC Standing Committee on Toxicity.
ii) On the basis of a drinking water study using rats (Johnson et al. 1986), the excess cancer risk of lifetime consumption of water with an acrylamide concentration of 0.00005 mg/L (50 ng/L) was conservatively estimated by the World Health Organization (WHO), using a linear multistage model, at one additional cancer per million people.
The guideline value was set at the limit of determination because this is within the values derived from health considerations, and provides an adequate degree of protection. This is consistent with the general approach adopted for compounds that are known genotoxic carcinogens (see Section 6.4). The higher WHO guideline value of 0.0005 mg/L is based on an estimated lifetime risk of one additional cancer per 100,000 people.
References
Brown L, Rhead MM (1979). Liquid chromatographic determination of acrylamide monomer in natural and polluted aqueous environments. Analyst, 104:391–399.
Burek JD, Albee RR, Beyer JE, Bell TJ, Carreon RM, Morden DC, Wade CE, Hermann EA, Gorzinski SJ (1980). Subchronic toxicity of acrylamide administered to rats in the drinking water followed by up to 144 days of recovery. Journal of Environmental Pathology and Toxicology, 4:157–182.
IARC (International Agency for Research on Cancer) (1994). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Some Industrial Chemicals. World Health Organization, IARC, 60, Lyon.
IPCS (International Programme on Chemical Safety) (1985). Acrylamide. Environmental Health Criteria, 49. World Health Organization, IPCS.
Johnson KA, Gorzinski SJ, Bodner KM, Campbell RA, Wolf CH, Friedman MA, Mast RW (1986). Chronic toxicity and oncogenicity study on acrylamide incorporated in the drinking water of Fischer 344 rats. Toxicology and Applied Pharmacology, 85:154–168.
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