Environmental hazard assessment: Di-(2-ethylhexyl)phthalate
Report No DWI0633



Properties: Di-(2-ethylhexyl)phthalate (DEHP) is a non-volatile liquid which is used extensively in the plastics processing industry as a plasticiser (increasing the flexibility of plastics, mainly PVC).

Production: Nine suppliers of phthalic acid esters were identified in the United Kingdom, but no information was available on the actual number of sites of DEHP production in this country. An estimated 33,000 tonnes of octyl phthalates, i.e. DEHP and di -iso-octyl phthalate, were produced in the UK in 1989, and an estimated 66,000 tonnes of octyl phthalates were used in the UK in the same year.

Release: DEHP is released into the UK environment as a result of its production and its later use in plastics processing. DEHP will also be released from plasticised products during their use and after their disposal. This release pattern ensures that DEHP is distributed throughout the whole environment. A worst case annual release of 1,220 tonnes DEHP was estimated for the UK from all sources. Any natural sources of DEHP were considered to be negligible compared to anthropogenic sources.

Fate: The fate of DEHP in the environment is influenced by its low volatility and its high potential for accumulation. Biodegradation of DEHP occurs fairly rapidly under aerobic conditions; it is not thought that abiotic processes (hydrolysis, photolysis etc) contribute greatly to the overall removal of DEHP from the environment. DEHP readily accumulates in aquatic sediments, suspended particulate material, and in the lipid tissues of aquatic biota. DEHP is also strongly held by soil solids and organic material in the terrestrial environment.

Effects: The acute toxicity of DEHP to aquatic organisms is generally low, with 96h LC50s of > 10 mg/l, although more recent acute toxicity values have been found which are lower than this; more sensitive indicators, such as reproduction and biochemical changes, have also been affected at lower concentrations. The acute toxicity of DEHP is low for micro-organisms, amphibians, plants, birds and mammals. The maximum measured environmental levels of DEHP in freshwater are greater than those at which both acute effects and marginal chronic effects on aquatic organisms have been observed in laboratory studies. It is therefore possible that both acute and chronic effects on aquatic organisms may be observed as a result of DEHP exposure in the real environment. Elevated levels of phthalates have been measured on sediments, and adverse effects may be noted on sediment-dwelling organisms.

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