Endrin in freshwater and marine water
Toxicant default guideline values for protecting aquatic ecosystems
Extracted from Section 8.3.7 ‘Detailed descriptions of chemicals’ of the ANZECC & ARMCANZ (2000) guidelines.
The default guideline values (previously known as ‘trigger values’) and associated information in this technical brief should be used in accordance with the detailed guidance provided in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality.
Description of chemical
Most organochlorine pesticides have been phased out of use in recent years, mainly because of their residual properties and potential for bioaccumulation. The guideline trigger values stated are for toxicity only and need to be adjusted for bioaccumulation where appropriate. Where the statistical distribution method was used, figures quoted are the 95% protection levels, usually applicable to slightly to moderately disturbed systemsalthough 99% protection figures are recommended for chemicals that bioaccumulate.
Endrin (CAS 72-20-8) is a persistent cyclodiene insecticide. Its chemical name is 1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo-5,8-dimethanonaphthalene. Its formula is C12H8Cl6O and molecular weight is 380.9. It has very low solubility in water (200 µg/L) and high log Kow of 5.6. The current analytical practical quantitation limit (PQL) for endrin is 0.05 µg/L (NSW EPA 2000).
Uses and environmental fate
Endrin has previously had uses in agriculture and as a termiticide but has not been used in Australia for at least 10 years. Endrin rapidly bioaccumulates in fish to BCF levels between 400 and 2000.
The toxicity of endrin was very high to almost all test species.
Freshwater fish: 22 spp, 48 to 96-hour LC50, 0.06to 31.00 µg/L, with most figures being below 7.00 µg/L. Higher figures were usually with nominal concentrations and some individual outlying figures were reported for Cyprinus carpio (49, 141 and 137 µg/L) and Gambusia affinis (88 and 2010 µg/L). Salmonids tended to be most sensitive. Chronic no observed effect concentration (NOEC) figures of 0.29 µg/L (140-d mortality) and 0.22 µg/L (110-day reproduction) were reported for Jordanella floridae giving an acute-to-chronic ratio (ACR) of 3.9. A 30-day growth NOEC for Pimephales promelas was 0.2 µg/L and 300-day mortality was 0.14 µg/L. The overall ACR of 10, instead of the empirical 5.8, was applied to provide an adequate margin of safety for toxicity.
Freshwater crustaceans: 10 species, 48 to 96-hour LC50 or EC50 (immobilisation), 0.5 to 74 µg/L. Sowbugs (Asellus), ostracods and prawns were most sensitive. Some outlying figures were reported for Daphnia magna (88 and 230 µg/L, (AQUIRE 1994) but also a low figure of 0.57 µg/L.
Freshwater amphibians: 10 species, 96-hour LC50, 0.21 to 180 µg/L, with marked differences for different species.
Freshwater insects: 11 species 48 to 96-hour LC50, 0.08 to 2.40 µg/L. Stoneflies and midges were most sensitive. Higher figures were reported for additional species, a cranefly Tipula sp. (12 µg/L) and a mayfly (Hexagenia bilineata 62 µg/L).
Freshwater algae: the only figure was a 36-hour NOEC for growth of 95 µg/L.
Marine fish: 17 species, 48 to 96-hour LC50, 0.09 to 2.60 µg/L. Chronic NOEC figures: Cyprinodon variegatus (28 to 175-day growth, 0.12 µg/L, giving an ACR of 3); Gasterosteus aculeatus (9-day hatching, 0.19 µg/L).
Marine crustaceans: seven species, 48 to 96-hour LC50 of 0.2 to 1.7 µg/L although additional species, Penaeus duorarum, had 96-hour LC50 of 0.037 and one species of crab, 15 to 25 µg/L. Chronic NOEC figures were reported for Palaeomonetes pugio (145 days) of 0.03 to 0.05 µg/L (growth) and 0.05 to 0.11 µg/L (mortality).
Marine echinoderms: one species, 72-hour LC50, 360 µg/L.
Marine algae: only 24-hour figures were available for two species of diatom (0.1 and 100 µg/L) and 36-hour NOEC for growth of a blue–green algae, 0.067 µg/L.
Australian and New Zealand data
The 96-hour LC50 to the introduced mosquitofish Gambusia holbrooki was 0.3 to 1.0 µg/L and to the firetail gudgeon Hypseleotris gallii was 0.55 µg/L.
Factors that modify toxicity
Toxicity of endrin was increased by a factor of 2 to Oncorhynchus mykiss and P. promelas between 2°C and 29°C (Johnson & Finley 1980). Hardness had little effect on toxicity.
A freshwater moderate reliability guideline figure of 0.02 µg/L was derived for endrin using the statistical distribution method with 95% protection and the default ACR of 10. The 99% protection level is 0.01 µg/L and is recommended as the trigger value for slightly to moderately disturbed systems. The overall ACR of 10, instead of the empirical 5.8, was applied to provide an adequate margin of safety for acute toxicity.
A marine moderate reliability guideline figure of 0.008 µg/L was derived for endrin using the statistical distribution method with 95% protection. The 99% protection level is 0.004 µg/L and is recommended as the trigger value for slightly to moderately disturbed systems.
Both figures would need to be adjusted for bioaccumulation. Users are advised to apply the 99% protection level if there are no data to adjust for bioaccumulation at the specific slightly to moderately disturbed site (Section 220.127.116.11 of the ANZECC & ARMCANZ 2000 guidelines). In addition, the 95% protection figure is only 3-fold lower than the lowest freshwater acute fish value.
AQUIRE (Aquatic Toxicity Information Retrieval Database) 1994. AQUIRE standard operating procedures. USEPA, Washington, DC.
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.
Johnson WW & Finley MT 1980. Handbook of acute toxicity of chemicals to fish and aquatic invertebrates. US Department of the Interior, Fish and Wildlife Service, No 137, Washington DC.
NSW EPA 2000. Analytical Chemistry Section, Table of Trigger Values 20 March 2000, LD33/11, Lidcombe, NSW.