Chlordane in freshwater and marine water

​​​Toxicant default guideline values for protecting aquatic ecosystems​

October 2000

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 systems although 99% protection figures are recommended for chemicals that bioaccumulate.

Chlordane (CAS 12789-03-6 or 57-74-9) is a persistent organochlorine cyclodiene insecticide first introduced by Velsicol Chemical Corporation. The technical compound is made up of a number of stereoisomers. Its chemical name is 1,2,4,5,6,7,8,8-octachloro-2,3,3a,4,7,7a-hexahydro-4-7-methanoindene, its formula is C₁₀H₆Cl₈ and molecular weight is 409.8. It has very low solubility in water, 0.1 mg/L at 25°C, and a high log K_ow. It is a non-systemic insecticide, which acts by contact, ingestion and inhalation and has long residual activity (Tomlin 1994). The current analytical practical quantitation limit (PQL) for chlordane is 0.06 mg/L (NSW EPA 2000).

Uses and environmental fate

Chlordane was used on a variety of insect pests in areas not involving food or food crops, particularly lawn beetles and subterranean termites. It was its residual action that made the use of chlordane and related cyclodienes attractive for sub-floor treatment against termites and it was registered for that use through much of Australia until 1994.

Chlordane is very persistent in soil with a DT50 (time to 50% degradation) around 1 year. It was found to be widespread in samples of the fish, Cheilodactylus fuscus, collected near Sydney’s sewer outfalls, prior to contribution of the deep ocean outfalls (ANZEC 1991), and was one of five organochlorines most commonly identified in fish at that time (Miskiewicz & Gibbs 1994). Levels have declined since opening of the deep ocean outfalls (Scanes & Phillip 1995).

Aquatic toxicology

The toxicity of chlordane to most species was very high. Data more than 2 times the water solubility were excluded.

Freshwater fish: 21 spp, 48 to 96-hour LC50, 0.8 to 115 µg/L. Outlying figures far exceeding water solubility of chlordane were reported for additional two Notopterus sp. 405 to 9730 µg/L and 180 µg/L for Labeo rohita (included in the 17 spp). Chronic NOEC figures: for Lepomis macrochirus (285-day, 0.54 µg/L, giving an acute-to-chronic ratio, or ACR, of 140) and Pimephales promelas (60-day, 0.75 µg/L, giving an ACR of 50).

Freshwater crustaceans: 10 spp, 48 to 96-hour LC50 or EC50 (immobilisation) of 0.4 to 63.0 µg/L. Palaeomonetes kadiakensis was most sensitive (0.4 to 10.0 µg/L) and a single outlying figure of 270 µg/L was reported for Daphnia magna. Chronic NOEC figures were reported for D. magna (28-day, 12 µg/L) and an additional test species, Hyalella azteca (65-day, 5.3 µg/L).

Freshwater insects: 2 spp, 96-hour LC50, 15 µg/L for a stonefly and 1440 µg/L for a midge, the latter well above water solubility.

Freshwater mollusc: 1 sp, 96-hour LC50, 1250 µg/L, which exceeds the water solubility.

Freshwater annelid: 1 sp, 48-hour EC50 (immobilisation), 1000 to 2000 µg/L, above the solubility.

Freshwater algae: 1 sp, 96-hour EC50 (biomass), 360 µg/L, above the solubility.

Freshwater mesocosms: Johnson and Finley (1980) reported a LOEC for invertebrate populations of 0.37 µg/L but test conditions could not be assessed.

Marine fish: 5 spp, 48 to 96-hour LC50, 3.2 to 90.0 µg/L. Stickleback Gasterosteus aculeatus were much less least sensitive than other species which were < 25 µg/L. Chronic NOEC figures were reported for Cyprinodon variegatus of 0.5 µg/L (hatching, 189 d) and 0.8 to 3.3 µg/L (28 to 148-day, mortality).

Marine invertebrates: 4 spp, 48 to 96-hour LC50, 0.4 to 4.8 µg/L. Chronic NOEC figures of 0.015 to 1.000 µg/L (20 to 90 days) were reported for the crab, Cancer magister (an additional test species).

Marine molluscs: 1 sp, 96-hour EC50 (growth), 6.2 to 10.0 µg/L.

Factors affecting toxicity

Temperature changes had little effect on toxicity of chlordane. The cis-isomer was around 7 times more toxic than the trans-isomer and persisted longer in ponds (Johnson & Finley 1980).

Guideline

References

ANZEC 1991. Persistent organochlorine compounds in the marine environment. Australian and New Zealand Environment Council, Australian Government Publishing Service, Canberra.

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.

Miskiewicz AG & Gibbs PJ 1994. Organochlorine pesticides and hexachlorobenzene in tissues of fish and invertebrates caught near a sewage outfall. Environmental Pollution 84, 269-277.

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

Scanes PR & Phillip N 1995. Environmental impact of deepwater discharge of sewage off Sydney, NSW, Australia. Marine Pollution Bulletin 26, 687-691.

Tomlin C 1994. The pesticide manual: A world compendium. 10th edn, British Crop Protection Council & Royal Society of Chemistry, Bath, UK.