Formaldehyde
(endorsed 1996)
Guideline
Based on health considerations, the concentration of formaldehyde in drinking water should not exceed 0.5 mg/L.
General description
Formaldehyde may be present in drinking water through ozonation of naturally occurring humic material, contamination by accidental spills, or deposition from the atmosphere. Typical concentrations in air are probably in the low parts-per-billion range. Overseas, formaldehyde has been detected in ozonated drinking water at concentrations up to 0.03 mg/L.
Formaldehyde is used industrially in the wood, paper and textile industries. It is also used in the production of a number of chemicals and for the preservation of biological material. It is occasionally used as a disinfectant, sometimes to disinfect water filters. Other sources of exposure include cigarette smoke and food. Formaldehyde is present in almost all common foods, and adult dietary intake is estimated at 11 mg/day. Drinking water would contribute less than 10% of total intake.
Typical values in Australian drinking water
No data are available on the concentrations of formaldehyde in Australian drinking waters.
Treatment of drinking water
There are no published reports on methods for the removal of formaldehyde from drinking water.
Measurement
Formaldehyde can be determined by formation of the 2,4-dinitro-phenylhydrazone derivative followed by analysis with high performance liquid chromatography with UV detection (Whittle and Rennie 1988). The limit of determination is 0.006 mg/L.
Health considerations
Formaldehyde is readily absorbed from the gastrointestinal tract and is rapidly metabolised to formic acid and subsequently to carbon dioxide and water.
An extensive review and summary of the human and animal toxicity data for formaldehyde is available (IPCS 1989).
Most human health data are from inhalation studies, where formaldehyde causes irritation of the respiratory tract, and dermal studies, where it causes skin irritation. Formaldehyde has been linked to outbreaks of haemolytic anaemia in patients using improperly serviced dialysis units, where formaldehyde was used to disinfect the units and residual amounts remained in the water filter.
A number of epidemiological studies have looked at the effects of inhalation of formaldehyde. No effects could be directly attributed to long-term occupational exposure, but studies among exposed workers have reported elevated incidences of a number of cancers including nasal, buccal, nasopharyngeal, skin, prostate and colon cancers. The available human evidence indicates that formaldehyde does not have a high carcinogenic potential (IPCS 1989).
In a 2-year drinking water study using rats, severe damage to gastric mucosa was reported only at the highest doses (over 80 mg/kg body weight per day), but no tumours were observed, either in the stomach or at other sites. Other studies have shown similar pathological changes to the stomach, but again only at the highest doses.
There was no evidence of tumour-promoting activity when formaldehyde was applied to mouse skin, but rats inhaling formaldehyde exhibited a markedly increased incidence of cancer of the nasal cavity. Formaldehyde has demonstrated mutagenic activity when applied to cells in vitro but not when applied in vivo.
The International Agency for Research on Cancer has concluded that formaldehyde is probably carcinogenic to humans (Group 2A, limited human evidence, sufficient animal evidence, based on inhalation studies) (IARC 1987). The weight of evidence indicates that formaldehyde is not carcinogenic by the oral route.
Derivation of guideline
The guideline value for formaldehyde in drinking water was determined as follows:
where:
15 mg/kg body weight per day is the no-effect level based on a 2-year drinking water study in rats (Til et al. 1989).
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.
100 is the safety factor in using the results of an animal study as a basis for human exposure (10 for interspecies variations and 10 for intraspecies variations). The use of this safety factor was recommended by the NHMRC Standing Committee on Toxicity.
The World Health Organization derived a guideline value of 0.9 mg/L based on a 20% allocation of total daily intake to drinking water. In determining the Australian guideline value, it was felt that sufficient data were available to indicate that 10% was a more realistic figure.
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) (1989). Formaldehyde. Environmental Health Criteria, 89. World Health Organization, IPCS.
Til HP, Woutersen RA, Feron VJ, Hollanders VHM, Falke HE, Clary JJ (1989). Two-year drinking water study of formaldehyde in rats. Food and Chemical Toxicology, 27:77–87.
Whittle PJ, Rennie PJ (1988). Determination of formaldehyde in river water by high-performance liquid chromatography. Analyst, 113:665–666.
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