Nitrobenzenes 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
Nitrobenzenes are used in the manufacture of rubber, photographic chemicals, and the production of aniline and dyestuffs (CCREM 1987). Little is known about their fate in the aquatic environment, but they have relatively low octanol-water partition coefficients and are not expected to bioaccumulate appreciably (CCREM 1987).
Nitrobenzene (CAS 98-95-3) has a log Kow of 1.85 and is soluble in water to 1.9 g/L at 20°C. World production of nitrobenzene exceeds 900,000 tonnes/year (Quarterman et al. 1996). Major routes of environmental fate are volatilisation, and slow aerobic biodegradation. Nitrobenzene has a low propensity to adsorb soil and sediments and is mobile in soil (Quarterman et al. 1996). Photolysis and chemical reaction in water are slow. The current analytical PQL for nitrobenzene is 5 µg/L (NSW EPA 2000).
Nitrobenzene is highly toxic to amphibians, moderately toxic to algae and marine invertebrates, but has low toxicity to other aquatic species. No data were available regarding chronic toxicity of nitrobenzene to saltwater organisms (USEPA 1986).
Freshwater fish: six species, 48 to 96-hour LC50, 1.8 to 156 mg/L (i.e. x 1000 µg/L). A chronic no observed effect concentration (NOEC) figure of 38.3 mg/L was reported for Pimephales promelas (immobilisation).
Freshwater crustacean: one species, 48-hour, 27 to 33 mg/L for Daphnia magna. Chronic NOEC figure for D. magna (21-days) was 2.6 mg/L (reproduction, measured figures).
Freshwater protozoan: one species, 60-hour LC50, 143 mg/L.
Freshwater algae: three species, 96-hour LC50, 18.0 to 23.8 mg/L.
Marine fish: one species, 96-hour LC50, 59 mg/L.
Marine algae: one species, 96-hour EC50 (mortality), 10.3 mg/L.
Some of these data are reproduced in Table 8.3.15 of the ANZECC & ARMCANZ (2000) guidelines for comparison with other nitrobenzenes.
Freshwater toxicity data and guideline values or environmental concern levels (ECLs) for methoxynitrobenzenes are detailed in Table 8.3.15 of the ANZECC & ARMCANZ (2000) guidelines. Except for the methoxy-substituted nitrobenzenes, most of the data indicated that substituted nitrobenzenes had higher toxicity than nitrobenzene.
Toxicity data for chloro- and fluoro-substituted nitrobenzenes to freshwater organisms are given in Table 8.3.16 of the ANZECC & ARMCANZ (2000) guidelines. Although data are sparse, an increase in the number of chlorine or nitro groups generally resulted in increased toxicity.
Factors modifying toxicity
No data were available.
A moderate reliability freshwater trigger value of 550 µg/L was derived for nitrobenzene using the statistical distribution method with 95% protection and an acute-to-chronic ratio (ACR) of 11.5. Low reliability trigger values are listed in Tables 8.3.15 and 8.3.16 of the ANZECC & ARMCANZ (2000) guidelines for other nitrobenzenes.
Marine data were only available for nitrobenzene (a fish and a crustacean) and 1-chloro-3-nitrobenzene (fish: one species, 96-h LC50, 550 µg/L). Hence only low reliability marine trigger values could be derived, as indicated in Tables 8.3.15 and 8.3.16 of the ANZECC & ARMCANZ (2000) guidelines. In most cases these were taken from the freshwater figures.
In all cases, low reliability trigger values should only be used as indicative interim working levels.
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.
CCREM 1987. Canadian water quality guidelines. Canadian Council of Resource and Environment Ministers, Ontario.
NSW EPA 2000. Analytical Chemistry Section, Table of Trigger Values 20 March 2000, LD33/11, Lidcombe, NSW.
Quarterman P, Crookes MJ, Howe P & Dobson S 1996. Environmental hazard assessment: Nitrobenzene. TSD 24. Toxic Substance Division, Department of the Environment, Garston, UK.
USEPA 1986. Quality criteria for water. US Department of Commerce, National Technical Information Service, US Environmental Protection Agency, Springfield, Virginia. PB87-226759, EPA 440/5 86-001.