Diethylphthalate 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
Diethylphthalate (CAS 84-66-2) is a phthalate ester.
Phthalate esters represent a large family of chemicals widely used as plasticisers, primarily in the production of polyvinyl chloride (PVC) resins (USEPA 1980e). Other applications are found in cosmetics, rubbing alcohol, insect repellent, insecticides and tablet coatings (CCREM 1987). Although phthalate esters are insoluble in pure water, they may be transported in the aquatic environment in solubilised forms by fulvic and humic acids. This solubilisation has been found to be pH-dependent (CCREM 1987). Depending on specific conditions in aquatic ecosystems, bioaccumulation and biodegradation will also be significant (CCREM 1987, Brooke et al. 1991). Log Kow values vary from 1.5 to 4, indicating some potential for bioaccumulation for the longer chain esters (CCREM 1987). The current analytical practical quantitation limit (PQL) for dimethyl-, diethyl- and dibutylphthalate is 2 µg/L (NSW EPA 2000).
Phthalate esters are a diverse group of organic compounds and toxicity in aquatic ecosystems varies with the ester tested. The insolubility of some phthalate esters in water makes it difficult to determine the actual concentrations used in toxicological tests (Brooke et al. 1991), and results exceeding water solubility were not considered. Appropriate acute toxicity data for freshwater organisms were available for five esters: butylbenzyl phthalate, diethyl phthalate, dimethyl phthalate, di-n-butyl phthalate and di-2-ethylhexylphthalate (USEPA 1980e). The sensitivity of fish and invertebrates was generally similar, with most values exceeding 1000 µg/L. Concentrations causing chronic toxicity in freshwater animals were as low as 3 µg/L (USEPA 1986).
Freshwater fish: 3 spp, 96-hour LC50, 12,000 to 17,000 µg/L.
Freshwater crustacean: Daphnia magna, 48-hour EC50, 86,000 µg/L; 21-d NOEC (reproduction) 25,000 µg/L.
Freshwater insects: Paratanytarsus. sp (midge), 96-hour LC50, 13,100 µg/L.
Freshwater algae: Selenastrum capricornutum, 96-hour EC50 (mortality), 16,000 µg/L.
Marine fish: Cyprinodon variegatus, 96-hour LC50, 2900 µg/L.
Marine crustacean: Mysidiopsis bahia, 96-hour LC50, 10,300 µg/L.
A freshwater moderate reliability trigger value of 1000 µg/L was derived for diethylphthalate by the statistical distribution method with 95% protection and the default acute-to-chronic ratio (ACR). As marine species (limited data) appear to be more sensitive, the 99% protection level (900 µg/L) is recommended for marine slightly-moderately disturbed systems. This figure should only be used as an indicative interim working level.
Some data could not be used as it was well above the solubility of 2-DEHP. Larsson and Thuren (1987) tested the hatching of frog eggs in a laboratory model ecosystem and found that elevated levels of DEHP in sediment affected the hatching of frogs and bioaccumulation in tadpoles.
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.
Brooke DN, Nielsen IR, Dobson S & Howe PD 1991. Environmental hazard assessment: Di-(2-ethylhexyl) phthalate. TSD 2, UK Department of the Environment, Garston.
CCREM 1987. Canadian water quality guidelines. Canadian Council of Resource and Environment Ministers, Ontario.
Larsson P & Thuren A 1987. Di-2-ethyl hexyl phthalate inhibits the hatching of frog eggs and is bioaccumulated by tadpoles. In Phthalate esters in the environment: analytical methods, occurrence, distribution and biological effects, ed A Thuren, Department of Ecology, Lund University, Lund, Sweden, 69–74.
NSW EPA 2000. Analytical Chemistry Section, Table of Trigger Values 20 March 2000, LD33/11, Lidcombe, NSW.
USEPA 1980e. Ambient water quality criteria for phthalate esters. Criteria and Standards Division, US Environmental Protection Agency, Washington DC.