Deltamethrin
(endorsed 2011)
Guideline
Based on human health concerns, deltamethrin in drinking water should not exceed 0.04 mg/L.
Related chemicals
Deltamethrin (CAS 52918-63-5) is in the pyrethroid class of chemicals. Other pesticides in this class include cyfluthrin, cypermethrin, alpha-cypermethrin and permethrin (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, deltamethrin would not be a health concern unless the concentration exceeded 0.04 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: Deltamethrin is an insecticide and parasiticide used for the control of a range of insects in various situations.
There are 70 products containing deltamethrin. They are intended for both professional and home garden use. For professional use, deltamethrin may be applied either as a pour-on, or as a spray, using ground or aerial methods of application. For home garden use, deltamethrin is generally available as pre-prepared spray or aerosol.
Exposure sources: The main source of public exposure to deltamethrin is residues in food. Residues levels in food produced according to good agricultural practice are generally low.
Agricultural use of deltamethrin may potentially lead to the contamination of source waters through processes such as run-off, spray drift or entry into groundwater.
Typical values in Australian drinking water
No data are available on the concentrations of deltamethrin in Australian drinking waters or in drinking water overseas.
Treatment of drinking water
There are no reports of the treatment of deltamethrin in drinking water.
Measurement
Several methods have been reported for the analysis of deltamethrin in water including liquid chromatography with electrospray ionisation mass spectrometry, with a limit of detection (LOD) of 0.2 ng/L in groundwater and 0.3 ng/L in sea water (Gil-Garcia et al. 2006); gas chromatography with micro-electron capture detection, LOD 0.81 ng/L (Casas et al. 2006); and gas chromatography-high resolution mass spectrometry, LOD 0.74 ng/L (Woudneh and Oras 2006).
History of the health values
The current acceptable daily intake (ADI) for deltamethrin is 0.01 mg per kg of bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 1 mg/kg bw/day from a long-term dog study. This NOEL is based on clinical effects, including dilation of the pupils, decreased weight gain, vomiting and diarrhoea. The ADI incorporates a safety factor of 100 and was established in 1980.
A health value has not previously been established by NHMRC.
Health considerations
Metabolism: Deltamethrin is rapidly absorbed via the gastrointestinal tract. It is extensively metabolised and excreted. The principal routes of metabolism are ester cleavage and oxidation at the 4-position of the alcohol moiety.
Acute effects: Deltamethrin has moderate to high acute oral toxicity and low acute dermal toxicity. It is not a skin sensitiser. Production and agricultural workers have reported irritation to the skin and mucous membranes, which last for several days.
Short-term effects: Medium-term dietary exposure in rats and dogs resulted in decreased bodyweight gain at the highest doses tested, namely, 2.5 mg/kg bw/day and 1 mg/kg bw/day, respectively. This was not accompanied by any pathological changes.
Long-term effects: Long-term dietary studies in mice, rat and dogs reported no significant toxic effects at dose levels of 15, 2.1 and 1.0 mg/kg bw/day, respectively.
Carcinogenicity: Based on long-term studies in mice and rats, there is no evidence of carcinogenicity for deltamethrin.
Genotoxicity: Deltamethrin is not considered to be genotoxic, based on in vitro and in vivo short-term studies.
Reproductive and developmental effects: In a multigenerational reproduction study in rats and in developmental studies in mice, rats and rabbits, there was no evidence of effects on reproductive parameters or on foetal development.
Poisons Schedule: Deltamethrin is included in Schedule 5, 6 or 7 of the Standard for the Uniform Scheduling of Medicines and Poisons No.1, 2010 (the Poisons Standard)(DoHA 2010), depending on the concentration and use. Current versions of the Poisons Standard should be consulted for further information.
Derivation of health-based guideline
The health-based guideline of 0.04 mg/L for deltamethrin was determined as follows:
where:
1.0 mg/kg bw/day is the NOEL based on a long-term (2-year) toxicity 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 variation.
Deltamethrin is excluded from the World Health Organization drinking water guidelines because it is “unlikely to occur in drinking water” (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.
Casas V, Llompart M, Garcia-Jares C, Cela R, Dagnac T (2006). Multivariate optimisation of the factors influencing the solid-phase microextraction of pyrethroid pesticides in water. Journal of Chromatography A, 1124:148-156.
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.
Gil-Garcia MD, Barranco-Martinez D, Martinez-Galera M, Parrilla-Vazquez P (2006). Simple, rapid solid-phase extraction procedure for the determination of ultra-trace levels of pyrethroids in ground and sea water by liquid chromatography/electrospray ionisation mass spectrometry. Rapid Communications in Mass Spectrometry, 20:2395-2403.
Tomlin CD (ed) (2006). The Pesticide Manual: a world compendium, 14th Edition, British Crop Production Council, UK.
WHO (World Health Organization) (2006). Guidelines for Drinking-water Quality. 3rd Edition, First Addendum, WHO, Geneva, Switzerland.
Woudneh MB, Oros DR (2006). Quantitative determination of pyrethroids, pyrethrins and piperonyl butoxide in surface water by high-resolution gas chromatography/high resolution mass spectrometry. Journal of Agricultural and Food Chemistry, 54(19):6957-6962.
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