2,4,5-T in freshwater and marine water

​​Toxicant default guideline values for protecting aquatic ecosystems

October 2000

Description of chemical

2,4,5-T (2,4-5-trichlorophenoxyacetic acid) (CAS 93-76-5) is a chlorophenoxyacetic acidic herbicide, which is no longer in use in Australia. It was removed from use following concerns about effects of dioxin contaminants, mainly on human health. The current analytical practical quantitation limit (PQL) for 2,4,5-T in water is 0.2 mg/L (NSW EPA 2000).

Aquatic toxicology

Freshwater fish: 16 species, 48-96 h LC50, 150-61,000 µg/L (geometric mean for the most sensitive species, Oncorhynchus mykiss, was around 1100 µg/L).

Freshwater crustaceans: four species, 48-96 h LC50 or EC50, 120-88,000 µg/L.

Freshwater insects: one species, 96-h LC50, 13,000 µg/L.

Freshwater rotifer: three species, 13,000-112,900 µg/L.

No marine data were available.

Factors that modify toxicity

See 2,4-D for likely factors. None have been specifically listed for 2,4,5-T.

Guidelines

A freshwater moderate reliability trigger value of 36 µg/L was calculated for 2,4,5-T acid using the statistical distribution method with 95% protection and the default AF of 10. It is recommended that this be adopted as a low reliability marine guideline. This figure should only be used as an indicative interim working level.

References

ANZECC & ARMCANZ 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

NSW EPA 2000. Analytical Chemistry Section, Table of Trigger Values 20 March 2000, LD33/11, Lidcombe, NSW.​ ​​​​