Propiconazole
(endorsed 2011)
Guideline
Based on human health concerns, propiconazole in drinking water should not exceed 0.1 mg/L.
Related chemicals
Propiconazole (CAS 60207-90-1) is in the DMI: triazole class of chemicals. Other pesticides in this class include flutriafol, myclobutanil, paclobutrazol, and triadimefon (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, propiconazole would not be a health concern unless the concentration exceeded 0.1 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: Propiconazole is a broad-spectrum fungicide used to control a variety of fungi in food crops, and as turf and timber treatments.
There are registered products containing propiconazole in Australia. The products are intended for professional use only and are available as emulsifiable concentrate formulations, to be diluted and applied using ground or aerial spray methods. Data on currently registered products are available from the Australian Pesticides and Veterinary Medicines Authority.
Exposure sources: The main source of public exposure to propiconazole and its metabolites is residues in food. 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
No reports of propiconazole in Australian drinking waters have been identified.
Treatment of drinking water
There is insufficient information on the treatment of propiconazole in drinking water, but it is expected that advanced treatment methodologies such as ozonation and advanced oxidation would be effective.
Measurement
Propiconazole can be measured in drinking water by the use of high performance liquid chromatography–tandem mass spectrometry. The limit of detection for this approach has been reported as 0.05 ng/L (Van De Steene and Lambert 2008).
History of the health values
The current acceptable daily intake (ADI) for propiconazole is 0.04 mg per kg of bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 4.0 mg/kg bw/day from a 2-year dietary study in rats. The NOEL is based on decreased food consumption and decreased bodyweight gain. The ADI incorporates a safety factor of 100 and was established in 1983.
The previous guideline value was 0.0001 mg/L and previous health value was 0.1 mg/L (NHMRC and NRMMC 2004).
Health considerations
Metabolism: Propiconazole is rapidly and extensively absorbed via the gastrointestinal tract and widely distributed in various tissues. It is readily metabolised and excreted in faeces and urine within 144 hours (97%), and has low potential for bioaccumulation. The major metabolites of propiconazole are triazole derivatives of the parent compound and include 1,2,4-triazole, triazole alanine and triazole acetic acid.
Acute effects: Propiconazole has low oral and dermal acute toxicity. It is not a skin sensitiser.
Short-term effects: In medium-term dietary studies in rats, there was reduced bodyweight gain at 80 mg/kg bw/day. In medium-term studies in dogs, there were no adverse effects at dose levels up to 36 mg/kg bw/day.
Long-term effects: Long-term dietary studies were conducted in mice and rats. In mice, there were increased liver weights and associated changes in blood plasma enzymes at 50 mg/kg bw/day. In rats, there was reduced bodyweight gain at 20 mg/kg bw/day.
Carcinogenicity: Based on long-term studies in mice and rats, there is no evidence of carcinogenicity for propiconazole.
Genotoxicity: Propiconazole is not considered to be genotoxic, based on in vitro or in vivo short-term studies.
Reproduction and developmental effects: Two 3-generation reproduction studies in rats produced decreased bodyweight gain at high dose levels only. There was no evidence of effects on reproductive parameters. In developmental studies in rats and rabbits, there was no evidence of effects on foetal development in the absence of maternal toxicity.
Poisons Schedule: Propiconazole is included in Schedule 5 or 6 of the Standard for the Uniform Scheduling of Medicines and Poisons No.1, 2010 (the Poisons Standard)(DoHA 2010), depending on its concentration. Current versions of the Poisons Standard should be consulted for further information.
Derivation of the health-based guideline
The health-based guideline of 0.1 mg/L for propiconazole was determined as follows:
where:
4 mg/kg bw/day is the NOEL based on a long-term (2-year) 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 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.
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.
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.
Tomlin CD (ed) (2006). The Pesticide Manual: a world compendium, 14th Edition, British Crop Production Council, UK.
Van De Steene JC, Lambert WE (2008). Validation of a solid-phase extraction and liquid chromatography-electrospray tandem mass spectrometric method for the determination of nine basic pharmaceuticals in wastewater and surface water samples. Journal of Chromatography A, 1182(2):153-160.
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