Quintozene
(endorsed 2011)
Guideline
Based on human health concerns, quintozene in drinking water should not exceed 0.03 mg/L.
Related chemicals
Quintozene (CAS 82-68-8) belongs to the nitroaniline class of chemicals. There are no other registered pesticides in this chemical 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, quintozene would not be a health concern unless the concentration exceeded 0.03 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: Quintozene is a soil fungicide for the control of pathogenic fungi on turf, ornamentals, cotton seedlings, peanuts, and vegetable agricultural crops.
There are registered products that contain quintozene in Australia. The products are intended for professional use and are available as concentrated solutions to be applied directly to soil in diluted form using ground, aerial or hand-held sprays. Data on currently registered products are available from the Australian Pesticides and Veterinary Medicines Authority.
Exposure sources: The main source of public exposure to quintozene and its metabolites is residues in food. Residue levels in food produced according to good agricultural practice are generally low.
Agricultural use of quintozene 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 quintozene in Australian drinking waters have been identified.
Treatment of drinking water
No specific data on the treatment of quintozene in drinking water have been identified.
Measurement
No suitable techniques for the analysis of quintozene in drinking water have been identified. However, it is expected that a suitable method using high performance liquid chromatography–tandem mass spectrometry could be developed if required.
History of the health values
The current acceptable daily intake (ADI) for quintozene is 0.007 mg per kg of bodyweight (mg/kg bw), based on a no-observed-effect level (NOEL) of 0.7 mg/kg bw/day from a long-term (2-year) dietary study in dogs. The NOEL is based on evidence of mild liver toxicity (increased absolute and relative liver weights, hepatocyte enlargement and granulosis, and increased serum alkaline phosphatase and cholesterol). The ADI incorporates a safety factor of 100, and was first established in 1987.
The previous health value was 0.03 mg/L (NHMRC and NRMMC 2004).
Health considerations
Metabolism: Quintozene is readily absorbed from the gastrointestinal tract of rats. The compound is extensively metabolised, mostly via nitrogen reduction to form acetyl pentachlorophenyl cysteine and pentachloroaniline. Excretion is rapid, occurring mostly via urine and being complete by three days, with small amounts of unabsorbed parent compound also excreted in faeces.
Acute effects: Quintozene has low acute oral and dermal toxicity. It is a skin sensitiser in humans.
Short-term effects: A 28-day dietary study in dogs reported increased relative liver weights at a dose of 64 mg/kg bw/day, but with no histological examination of the liver. Medium-term dietary studies in rats and dogs did not show any evidence of toxicity up to 100 mg/kg bw/day in rats and up to 25 mg/kg bw/day in dogs.
Long-term effects: In long-term studies in rats (2-year) and dogs (1- and 2-year), there was decreased bodyweight gain and increased liver and kidney weight in both species at 6 mg/kg bw/day. There was also evidence of liver toxicity in rats (necrosis) at this dose level. In dogs, there was increased serum alkaline phosphatase, serum cholesterol, hepatocyte size and granulosis at 40 mg/kg bw/day. The lowest overall NOEL was 0.7 mg/kg bw/day in dogs.
Carcinogenicity: Based on 2-year studies in mice and rats, there is no evidence of carcinogenicity for quintozene.
Genotoxicity: Quintozene is not considered to be genotoxic, based on in vitro and in vivo short-term studies.
Reproductive and developmental effects: In a 2-generation reproduction study in rats, and in developmental studies in rats, mice and rabbits, there was no evidence of effects on reproductive parameters or foetal development.
Poisons Schedule: Quintozene is included in Schedule 5 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 0.03 mg/L for quintozene was determined as follows:
where:
0.7 mg/kg bw/day is the NOEL based on a long-term (2-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 variation.
The World Health Organization has not established a health-based guideline value for quintozene and it is excluded from the list of agricultural chemicals guideline value derivation because it is “unlikely to occur in drinking water” (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.
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.
WHO (World Health Organization) (2004). Guidelines for Drinking-water Quality. 3rd Edition, WHO, Geneva, Switzerland.
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