Flupropanate
(endorsed 2011)
Guideline
Based on human health concerns, flupropanate in drinking water should not exceed 0.009 mg/L.
Related chemicals
Flupropanate (CAS 756-09-2) belongs to the halogenated alkanoic acid class of chemicals. There are no other pesticides in this class (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, flupropanate would not be a health concern unless the concentration exceeded 0.009 mg/L. Excursions above this level even for a relatively short period are of concern as the health-based guideline is based on medium-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
Users: Flupropanate is a herbicide used to control the growth of grass weeds in industrial or pasture land.
There are registered products containing flupropanate in Australia. These are available as concentrated solutions applied as a dilute spray by aerial, ground boom or hand spray techniques. Data on currently registered products are available from the Australian Pesticides and Veterinary Medicines Authority.
Exposure sources: The potential sources of public exposure to flupropanate and its metabolites are residues in food and drinking water. Flupropanate is not registered for use on food crops and the maximum residue limits are set at the level of detection.
Agricultural use of flupropanate 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 flupropanate in Australian drinking waters have been identified.
Treatment of drinking water
There is insufficient information on the treatment of flupropanate in drinking water, but it is expected that advanced treatment methodologies such as ozonation and advanced oxidation would be effective.
Measurement
No suitable analytical techniques have been identified, but the use of high performance liquid chromatography with tandem mass spectrometry is expected to be suitable for residue levels of this pesticide in water.
History of the health values
The current acceptable daily intake (ADI) for flupropanate is 0.002 mg per kg of bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 5 mg/kg bw/day from a 90-day dietary rat study. The NOEL is based on effects on the liver. The ADI incorporates a safety factor of 2000 and it was established in 1987.
A health value has not been previously established by NHMRC.
Health considerations
Metabolism: No data are available on the absorption, distribution, metabolism or excretion of flupropanate.
Acute effects: Flupropanate has low acute oral and dermal toxicity. Its skin sensitisation potential is unknown.
Short-term effects: A 90-day dietary study in rats reported changes in liver weight at 15 mg/kg bw/day and changes in kidney weight at 50 mg/kg bw/day. The NOEL from the rat study was 5 mg/kg bw/day, and this is the basis of the ADI.
Long-term effects: A 1-year dietary study in mice reported kidney weight changes at 15 mg/kg bw/day and changes in bodyweight gain and liver weight, together with evidence of liver toxicity, at 30 mg/kg bw/day. The study was of poor quality and the NOEL of 7 mg/kg bw/day was not used to establish the ADI.
Carcinogenicity: There are no studies available to assess the potential carcinogenicity of flupropanate.
Genotoxicity: Only short-term bacterial in vitro studies were available, and based on these, flupropanate is not considered to be genotoxic; however, no in vitro mammalian studies or in vivo studies were available.
Reproductive and developmental effects: There were no data available on the reproductive effects of flupropanate. Developmental studies in mice and rats did not show any evidence of effects on foetal development; however, both studies were considered to be of poor quality.
Poisons Schedule: Flupropanate 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 value of 0.009 mg/L for flupropanate was determined as follows:
where:
5 mg/kg bw/day is the NOEL based on a medium-term (90-day) dietary study in rats.
70 kg is taken as the average weight of an adult.
0.1 is a proportionality factor based on the conservative 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.
2000 is a safety factor applied to the NOEL derived from animal studies. The safety factor incorporates a factor of 10 for interspecies extrapolation, 10 for intraspecies variations, and an additional factor of 20 for using a NOEL derived from a medium-term study.
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.
Tomlin CD (ed) (2006). The Pesticide Manual: a world compendium, 14th Edition, British Crop Production Council, UK.
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