Aniline in freshwater and marine water

Toxicant default guideline values for protecting aquatic ecosystems

October 2000

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

Aniline (CAS 62-53-3) is the simplest aromatic amine, with formula of C6H7N and molecular weight 93.1. It is moderately soluble in water to around 35 g/L to give an alkaline solution with pKa 4.6 and has a low log K_ow of 0.90. Its equilibrium with cationic species affects its properties in the environment. The current analytical PQL for aniline is 2 µg/L (NSW EPA 2000). The PQL for 2,4-DCA and 3,4-DCA is 10 µg/L.

The major use of aniline in the production of isocyanates for polyurethane resins, but it is also used for manufacture of dyes and rubber processing chemicals (Nielsen et al. 1993a). It is also a by-product of coke production.

Environmental fate

Aniline partitions readily to water, undergoes rapid photolysis and is readily biodegraded (Nielsen et al. 1993a). The half-life of evaporation of aniline under simulated stream conditions is 24 days (Lyman et al. 1982). It does not readily adsorb to sediments and does not significantly bioaccumulate. It is readily depurated from organisms. It adsorbs more strongly to soil under acidic conditions and in soils with higher organic matter.

Aquatic toxicology

Freshwater fish: eight species, 48-96 h LC50, 2200-187,000 µg/L. Chronic NOEC figure for P. promelas (7-d, growth and mortality) of 15,700 µg/L for Brachydanio rerio, 7-28 d reproduction of 5600-18,000 µg/L and 28-d mortality of 39,000 µg/L.

Freshwater amphibians: two species, 96-h LC50, 150,000-940,000 µg/L.

Freshwater crustaceans: six species, 48-96-h LC50 immobilisation, 80 (Daphnia magna) – 112,000 µg/L. The most sensitive were (as geometric means) D. pulex (100 mg/L), C. dubia (190 mg/L), D. magna (275–315 mg/L). Only Asellus aquaticus (68,000 µg/L) and Gammarus pulex (112,000 µg/L) had figures >700 µg/L. Chronic figures around 4-50 µg/L for D. magna were reported in AQUIRE (1994) but could not be found in the original reference.

Freshwater insects: 11 species, 48-96-h LC50, 64,000-478,000 µg/L.

Freshwater molluscs: two species, 48-96-h LC50, 31,600-800,000 µg/L.

Other freshwater invertebrates: four species, 48-96-h LC50, 31,600-760,000 µg/L.

Freshwater algae and ciliates: four species, 48-96-h EC50 growth, 1900-154,000 µg/L.

Marine crustacean: one species, 96-h LC50, 29,400 µg/L.

Australian and New Zealand data

A 72-h LC50 for the marine diatom Nitzschia closterium of 4660 µg/L is reported.

Factors causing variations in toxicity

There were only slight variations in toxicity of aniline to early developmental stages of three species of fish. Toxicity increased for catfish with increased hardness but decreased for goldfish and bass (Birge et al. 1979a).

Guidelines

A moderate reliability freshwater guideline value for aniline of 250 µg/L was derived using the statistical distribution method (95% protection) and ACR of 4.5.

The 99% protection figure was 8 mg/L. The 95% figure failed to protect several key crustacean test species from acute toxicity and it is recommended that the 99% protection figure be used for slightly to moderately disturbed ecosystems. As there were few marine data, the freshwater figure of 8 mg/L was adopted as a marine low reliability trigger value, for use only 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.

AQUIRE (Aquatic Toxicity Information Retrieval Database) 1994. AQUIRE standard operating procedures. USEPA, Washington, DC.

Birge WJ, Black JA, Hudson JE & Bruser DM 1979a. Embryo-larval toxicity tests with organic compounds. In Aquatic toxicology, eds LL Marking & RA Kimerle, ASTM STP 667, American Society for Testing and Materials, Philadelphia, Pa, 131-147.

Lyman WJ, Reehl WF & Rosenblatt DH 1982. Handbook of chemical property estimation methods. Environmental behaviour of organic compounds. McGraw-Hill Book Co, New York.

Nielsen IR, Diment J & Dobson S 1993a. Environmental hazard assessment: Aniline. TSD15. Toxic Substances Division, Department of the Environment, Garston, UK.

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