Aldrin and Dieldrin
(endorsed 2011)
Guideline
Based on human health concerns, aldrin and dieldrin when measured together in drinking water should not exceed 0.0003 mg/L.
Related chemicals
Aldrin and dieldrin (CAS 309-00-2/CAS 60-57-1) belong to the organochlorine class of chemicals and are classified as persistent organic pollutants (POP). Other POPs that were previously used as pesticides include DDT 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 contaminants in drinking water, aldrin and dieldrin when measured together would not be a health concern unless the concentration exceeded 0.0003 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: Aldrin and dieldrin have been used previously as insecticides for the control of soil-dwelling pests and for the protection of wood structures against termites and wood borers.
There are no registered products that contain aldrin or dieldrin in Australia, but de-registered compounds may still be detected in water.
Exposure sources: Aldrin is largely converted to dieldrin, which persists in the environment. The general public may be exposed to low levels of dieldrin through residues in food and/or contaminated source waters from previous use of aldrin and dieldrin as insecticides. The residue definition of aldrin and dieldrin is defined as “sum of HHDN (aldrin) and HEOD (dieldrin)”.
Typical values in Australian drinking water
No occurrence data of aldrin or dieldrin in Australian drinking water could be found. The concentrations of aldrin and dieldrin in aquatic environments and drinking water in industrialised countries are normally less than 0.01 μg/L (WHO 2003).
Treatment of drinking water
Aldrin is completely removed by either chlorination or activated carbon, while dieldrin is more recalcitrant, with removal efficacies of 30% for chlorination and 85% for activated carbon (Ormad et al. 2008).
Measurement
Aldrin and dieldrin are determined by extraction with pentane followed by gas chromatography with electron capture detection. The detection limits in tap water and river water are about 0.001 μg/L for aldrin and 0.002 μg/L for dieldrin (WHO 2003).
History of the health values
The current tolerable daily intake (TDI) for both aldrin and dieldrin is 0.0001 mg per kg bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 0.025 mg/kg bw/day from 2-year dietary studies in rats and dogs. The NOEL is based on liver damage. The TDI incorporates a safety factor of 250 and was established in 2003
When aldrin and dieldrin were in use in Australia, the ADI was 0.0001 mg/kg bw, based on a NOEL of 0.025 mg/kg bw/day from the long-term dietary studies. As aldrin and dieldrin are no longer used in agricultural practice in Australia, the ADI was not maintained.
The previous health value for aldrin and dieldrin was 0.0003 mg/L (NHMRC and NRMMC 2004).
Health considerations
Since aldrin is converted to dieldrin in the environment, the toxicity of dieldrin is the major consideration in relation to the health impact of aldrin and/or dieldrin in drinking water.
Metabolism: Aldrin and dieldrin are rapidly absorbed via the gastrointestinal tract in animals and humans. Aldrin is rapidly metabolised to dieldrin, and dieldrin is further metabolised, mainly in the liver. Aldrin and dieldrin accumulate in adipose tissue, from which they can be mobilised into blood. Some excretion of both compounds occurs, mainly as metabolites via urine and faeces. The major metabolite of dieldrin identified is the 9-hydroxy derivative.
Acute effects: Both aldrin and dieldrin have high acute oral and dermal toxicity. Skin sensitisation data are not available for aldrin or dieldrin.
Short-term effects: Short-term dietary studies in rats with both aldrin and dieldrin indicated an increase in relative liver weight and reversible hypertrophy of hepatocytes at dose levels above 5 mg/kg bw/day. In dogs, liver weight changes were observed at 0.05 mg/kg bw/day and muscular spasms and convulsions at high dose levels. In a two-year human volunteer study, no clinical signs of toxicity were reported up to doses of 0.2 mg/kg bw/day.
Long-term effects: Long-term dietary studies in mice, rats and dogs showed the liver to be the target organ of toxicity. In mice, there was liver enlargement and hyperplasia, and benign and malignant liver tumours at doses of 0.187 mg/kg bw/day and above. Clinical signs of toxicity, which included hair loss, diarrhoea, hyper-excitability, abdominal distention and tremors, were reported at doses of 0.5 mg/kg bw/day and above. Two-year dietary studies in rats and dogs reported by the Joint Meeting of Pesticide Residues (JMPR 1966, 1970, 1977) showed increased liver weights and microscopic liver lesions in rats at 0.1 mg/kg bw/day and above, and increased liver weight and liver damage at 0.075 mg/kg bw/day in dogs. The NOEL from these studies was 0.025 mg/kg bw/day, and this is the basis for the current Australian TDI.
Carcinogenicity: There was evidence of liver tumors in mice, but not rats, trout or hamsters. In epidemiological studies in workers, there was no evidence of an increased incidence of cancer related to exposure to aldrin and dieldrin.
Genotoxicity: Aldrin and dieldrin are not considered to be genotoxic, based on in vitro and in vivo short-term studies.
Reproductive and developmental effects: Reproductive studies in mice, rats and dogs up to 6 generations reported an increase in foetotoxicity and pre-weaning pup mortality at 0.125 mg/kg bw/day and above. Developmental toxicity studies in mice, rats and rabbits did not produce any evidence of effects on foetal development.
Immunotoxicity: There was no evidence of immunotoxicity based on studies in mice.
Poisons Schedule: Aldrin and dieldrin are 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 0.0003 mg/L for aldrin and dieldrin was determined as follows:
where:
0.025 mg/kg bw/day is the NOEL based on long-term (2-year) studies in rats and 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.
250 is the safety factor applied to the NOEL derived from animal studies. This safety factor incorporates a factor of 10 for interspecies extrapolation, 10 for intraspecies variation and an additional safety factor of 2.5 based on concern about carcinogenicity observed in mice.
The World Health Organization established a health-based guideline value of 0.00003 mg/L for aldrin and dieldrin in 2003 (WHO 2004).
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.
JMPR (Joint FAO/WHO Meeting on Pesticide Residues) (1966). Toxicological evaluation of aldrin (FAO/PL:CP/15).
JMPR (Joint Meeting on Pesticide Residues) (1970). Toxicological evaluation of dieldrin (AGP:1970/M/12/1).
JMPR (Joint Meeting on Pesticide Residues) (1977). Toxicological evaluation of aldrin/dieldrin (Pesticide residues in food: 1977 evaluations)
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.
Ormad MP, Miguel N, Claver A, Matesanz JM, Ovelleiro JL (2008). Pesticides removal in the process of drinking water production. Chemosphere, 71: 97-106.
Tomlin CD (ed) (2006). The Pesticide Manual: a world compendium, 14th Edition, British Crop Production Council, UK.
WHO (World Health Organization) (2003). Aldrin and Dieldrin in Drinking-water: Background document for development of WHO Guidelines for Drinking-water Quality. The World Health Organization.
WHO (World Health Organization) (2004). Guidelines for Drinking-water Quality. 3rd Edition, WHO, Geneva, Switzerland.
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