Endosulfan
(endorsed 2011)
Guideline
Based on human health concerns, endosulfan in drinking water should not exceed 0.02 mg/L.
Related chemicals
Endosulfan (CAS 115-29-7) is in the cyclodiene organochlorine class of chemicals. The other pesticide in this class is trinexapac-ethyl (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 in drinking water as a result of a spillage or through misuse, endosulfan would not be a health concern unless the concentration exceeded 0.02 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: Endosulfan is an insecticide used for the control a range of insects and mites on a broad spectrum of crops, as well as on cotton.
There are registered products containing endosulfan in Australia. The products are for professional use only and are available as emulsifiable concentrates to be diluted before use. Application is by aircraft, boom spray, or hand spray from the ground for crops other than cotton, and by aircraft for cotton crops. Data on currently registered products are available from the Australian Pesticides and Veterinary Medicines Authority.
Exposure sources: The main source of public exposure to endosulfan is residues in food. The residue levels in food produced according to good agricultural practice are generally low.
Agricultural use may potentially lead to contamination of source waters through processes such as run-off, spray drift or entry into groundwater.
Typical values in Australian drinking water
There are few available data on endosulfan concentrations in Australian drinking water. Treated sewage in Australia contains less than 0.5 µg/L (supporting data, NRMMC/EPHC/NHMRC 2008). Internationally, endosulfan contamination does not appear to be widespread in the aquatic environment, but has been found in agricultural run-off and rivers in industrialised areas where it is manufactured or formulated (IPCS 1984). Endosulfan (one or both of its isomers) has been identified in 24 surface water samples and 103 groundwater samples collected from 164 hazardous waste sites in the USA. Surface water samples in the USA generally contain less than 1 µg/L (ATSDR 2000).
Treatment of drinking water
Like many other pesticides, endosulfan is efficiently removed by activated charcoal (94% removal; Mishra and Patel 2007) and ozonation (94-97%; Yazgan and Kinaci 2003, Yazgan et al. 2003).
Measurement
The method of choice for the determination of endosulfan involves extraction from water with methylene chloride followed by gas chromatography combined with electron capture detection (WHO 2004a). In considering residue levels, the sum of the α- and β-somers plus the endosulfan sulfate metabolite, which is similar in toxicity to the parent compound, have to be considered. Detection limits are 0.015 μg/L for α-endosulfan, 0.024 μg/L for β-endosulfan and 0.015 μg/L for endosulfan sulfate (ATSDR 2000).
History of the health values
The current acceptable daily intake (ADI) for endosulfan is 0.006 mg per kg of bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 0.57 mg/kg bw/day for decreased bodyweight gain in a 12-month dietary study in dogs, and a NOEL of 0.66 mg/kg bw/day for decreased bodyweight gain and damage to kidney tissue in long-term studies in rodents and a developmental study in rats. The ADI incorporates a safety factor of 100 and was established in 1997.
The previous ADI, set in 1968, was 0.007 mg/kg bw, based on a NOEL of 0.7-0.75 mg/kg bw/day established in a 1-year dog dietary study, a 13-week rat dietary study, and rat reproduction and developmental studies, using a 100-fold safety factor.
The previous health value was 0.03 mg/L (NHMRC and NRMMC 2004).
Health considerations
Metabolism: Endosulfan is readily absorbed via the gastrointestinal tract and widely distributed in the body. It is extensively metabolised to sulfates and has a low potential for bioaccumulation. Excretion occurs mainly in faeces and is complete within 72 hours.
Acute effects: Endosulfan has a high acute oral and dermal toxicity. It is not a skin sensitiser.
Short-term effects: In short-term dermal studies in rats, endosulfan produced inhibition of serum and brain acetylcholinesterase and mild liver changes at 9 mg/kg bw/day. In medium-term dietary studies in mice and rats, there was an increase in granular pigment formation in the proximal tubule cells and increased kidney weight at 3.9 mg/kg bw/day and above.
Long-term effects: Long-term dietary studies were conducted in rodents and dogs. A 2-year rat study reported reduced bodyweight, an increased incidence of enlarged kidneys and blood vessel aneurysms, and marked progressive glomerulonephrosis at 2.9 mg/kg bw/day. A 1-year study in dogs reported decreased bodyweight gain at 0.75 mg/kg bw/day. The NOEL of 0.57 in rats and dogs is the basis for the current ADI.
Carcinogenicity: Based on long-term studies in mice and rats, there is no evidence of carcinogenicity for endosulfan.
Genotoxicity: Endosulfan is not considered to be genotoxic, based on in vitro and in vivo short-term studies.
Reproductive and developmental effects: A reproduction study in rats and developmental toxicity studies in rats and rabbits did not produce any evidence of effects on reproductive parameters or foetal development.
Poisons Schedule: Endosulfan is included in Schedule 6 and 7 of the Standard for the Uniform Scheduling of Medicines and Poisons No.1, 2010 (the Poisons Standard)(DoHA 2010) depending on concentrations and use patterns. Current versions of the Poisons Standard should be consulted for further information.
Derivation of the health-based guideline
The health-based guideline of 0.02 mg/L for endosulfan was determined as follows:
where:
0.57 mg/kg bw/day is the NOEL based on a long-term (1-year) dietary study in dogs.
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 ADI 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 variations.
The World Health Organization has not established a guideline value for endosulfan, because it occurs at concentrations well below those at which toxic effects are observed (WHO 2004b).
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.
ATSDR (Agency for Toxic Substances and Disease Registry) (2000) Toxicological profile for endosulfan. Published by the US Department of Health and Human Services, Public Health Service, ATSDR, Atlanta, GA.
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.
IPCS (International Programme on Chemical Safety) (1984). Endosulfan. Environmental Health Criteria 40. Published by the World Health Organization, IPCS, Geneva, Switzerland.
Mishra PC, Patel RK (2007). Removal of endosulfan by sal wood charcoal. Journal of Hazardous Materials 152(2):730-736.
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.
NRMMC (Natural Resource Management Ministerial Council), EPHC (Environment Protection and Heritage Council), NHMRC (National Health and Medical Research Council) (2008). Australian Guidelines for Water Recycling: Managing health and environmental risks (Phase 2) - Augmentation of drinking water supplies. NRMMC, EPHC, NHMRC.
Tomlin CD (ed) (2006). The Pesticide Manual: a world compendium, 14th Edition, British Crop Production Council, UK.
WHO (World Health Organization) (2004a). Endosulfan in drinking water. Background document for development of WHO Guidelines for Drinking-water Quality. World Health Organization, Geneva, Switzerland.
WHO (World Health Organization) (2004b). Guidelines for Drinking-water Quality. 3rd Edition, WHO, Geneva, Switzerland.
Yazgan MS, Kinaci C (2003). Beta-endosulfan removal from water by ozone oxidation. Water Science and Technology, 48(11-12): 511-517.
Yazgan MS, Kinaci C, Toroz I (2003). Ozonation of aqueous solution of alpha endosulfan. Journal of Environmental Science and Health Part B, 38(6):843-853.
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