Chlordane
(endorsed 2011)
Guideline
Based on human health concerns, chlordane in drinking water should not exceed 0.002 mg/L.
Related chemicals
Chlordane (CAS 57-74-9) belongs to the cyclodiene organochlorine class of chemicals. A currently used pesticide in this class is endosulfan. Chlordane is also classified as a persistent organic pollutant (POP). Other cyclodiene organochlorines that were previously used as pesticides include aldrin, dieldrin and heptachlor (Tomlin 2006).
Human risk statement
With good water quality management practices, the exposure of the general population is expected to be well below levels that may cause health concerns.
If present as a contaminant in drinking water, chlordane would not be a health concern unless the concentration exceeded 0.002 mg/L. Minor excursions above this level would need to occur over a significant period to be a health concern, as the health-based guideline is based on long-term effects.
With good water quality management practices, pesticides should not be detected in source waters used for drinking water supplies. Persistent detection of pesticides may indicate inappropriate use or accidental spillage, and investigation is required in line with established procedures in the risk management plan for the particular water source.
General description
Uses: Chlordane was used previously as an insecticide for the control of termites and soil insects.
There are no registered products that contain chlordane in Australia, but de-registered compounds may still be detected in water.
Exposure sources: The general public may be exposed to low levels of chlordane and its metabolites through residues in food and/or contaminated source waters from previous insecticidal use of chlordane.
Typical values in Australian drinking water
No specific reports of chlordane in Australian drinking waters have been identified. However, chlordane is a relatively commonly identified water contaminant in many parts of the world (Yamashita et al. 2000, Fatoki and Awofolu 2004, Singh et al. 2007, Kumari et al. 2008, Mmualefe et al. 2009).
Treatment of drinking water
No specific data on the treatment of chlordane in drinking water have been identified. It is expected that treatment by activated carbon should be effective under optimal conditions (WHO 2004).
Measurement
Chlordane is commonly measured in drinking waters by gas chromatography–electron capture detection, with a limit of detection of 0.014 µg/L (WHO 2004).
History of the health values
The current tolerable daily intake (TDI) for chlordane is 0.0005 mg per kg bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 0.045 mg/kg bw/day from a 130-week dietary rat study. The NOEL is based on effects in the liver. The TDI incorporates a safety factor of 100, and was established in 2003.
When chlordane was previously used, the acceptable daily intake (ADI) was 0.0005 mg/kg bw/day, based on a NOEL of 0.045 mg/kg bw/day from the same long-term dietary study.
The previous health value was 0.001 mg/L (NHMRC and NRMMC 2004).
Health considerations
Metabolism: Chlordane is readily absorbed via the gastrointestinal tract and is extensively metabolised to oxychlordane and heptachlor epoxide. It is mainly excreted in the faeces.
Acute effects: Chlordane has low/moderate acute oral toxicity and moderate dermal toxicity. It is not a skin sensitiser.
Short-term effects: A 30-day dietary study in mice reported histopathological changes in the liver at 1.4 mg/kg bw/day and above.
Long-term effects: Long-term dietary studies conducted in mice, rats and dogs showed the liver to be the target organ of toxicity. Effects on the liver were observed at 0.13 mg/kg bw/day in mice and 0.27 mg/kg bw/day in dogs. In a 130-week study in rats, increased absolute and relative liver weights, liver enlargement, hepatocellular swelling and necrosis were seen at dose levels above 0.045 mg/kg bw/day. The NOEL of 0.045 mg/kg bw/day is the basis for the current TDI.
Carcinogenicity: Carcinogenicity studies were conducted in mice and rats. There was evidence of liver tumours in mice at dose levels of 0.65 mg/kg bw/day and above. There was no evidence of carcinogenicity in rats.
Genotoxicity: Chlordane is not considered to be genotoxic, based on in vitro and in vivo short-term studies.
Reproductive and developmental effects: Reproduction studies in rats and mice reported reduced viability of offspring during weaning at 3 mg/kg bw/day and 7.5 mg/kg bw/day, respectively. Developmental studies in rabbits showed no effects on foetal development at doses up to 50 mg/kg bw/day.
Poisons Schedule: Chlordane is included in Schedule 6 of the Standard for the Uniform Scheduling of Medicines and Poisons No.1, 2010 (the Poisons Standard)(DoHA 2010). Current versions of the Poisons Standard should be consulted for further information.
Derivation of the health-based guideline
The health-based guideline of 0.002 mg/L for chlordane was determined as follows:
where:
0.045 mg/kg bw/day is the NOEL based on a long-term (130-week) dietary study in rats.
70 kg is taken as the average weight of an adult.
0.1 is a proportionality factor based on the assumption that 10% of the TDI will arise from the consumption of drinking water.
2 L/day is the estimated maximum amount of water consumed by an adult.
100 is the safety factor applied to the NOEL derived from animal studies. This safety factor incorporates a factor of 10 for interspecies extrapolation and 10 for intraspecies variation.
The World Health Organization established a health-based guideline value of 0.0002 mg/L for chlordane in 2003 (WHO 2006).
References
NOTE: The toxicological information used in developing this fact sheet is from reports and data held by the Department of Health, Office of Chemical Safety.
DoHA (2010) The Poisons Standard; Schedule 1-Standard for the Uniform Scheduling of Medicines and Poisons, Department of Health and Ageing, Commonwealth of Australia, Canberra.
Fatoki OS, Awofolu OR (2004). Levels of organochlorine pesticide residues in marine-, surface-, ground- and drinking waters from the Eastern Cape Province of South Africa. Journal of Environmental Science and Health Part B – Pesticides, Food Contaminants and Agricultural Wastes, 39(1):101-114.
Kumari B, Madan VK, Kathpal TS (2008). Status of insecticide contamination of soil and water in Haryana, India. Environmental Monitoring and Assessment, 136(1-3):239-244.
Mmualefe LC, Torto N, Huntsman-Mapila P, Mbongwe B (2009). Headspace solid phase microextraction in the determination of pesticides in water samples from the Okavango Delta with gas chromatography-electron capture detection and time-of-flight mass spectrometry. Microchemical Journal, 91(2):239-244.
NHMRC (National Health and Medical Research Council), NRMMC (Natural Resources Management Ministerial Council) (2004). Australian Drinking Water Guidelines. National Water Quality Management Strategy, Paper 6. NHMRC and NRMMC.
Singh KP, Malik A, Sinha S (2007). Persistent organochlorine pesticide residues in soil and surface water of northern Indo-Gangetic alluvial plains. Environmental Monitoring and Assessment, 125(1-3):147-155.
Tomlin CD (ed) (2006). The Pesticide Manual: a world compendium, 14th edition, British Crop Production Council, UK.
WHO (World Health Organization) (2004). Guidelines for Drinking-water Quality. 3rd Edition, WHO, Geneva, Switzerland.
Yamashita N, Urushigawa Y, Masunaga S, Walash MI, Miyazaki A (2000). Organochlorine pesticides in water, sediment and fish from the Nile River and Manzala Lake in Egypt. International Journal of Environmental Analytical Chemistry, 77(4):289-303.
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