Cleaner Technology Projects in Denmark 1996
Review of Environmental Fate and Effects of di(2-ethylhexyl)phthalate
Redegørelse over DEHP’s påvirkning af miljøet
Arbejdsrapport nr. 54, 1996, Miljøstyrelsen
Today there are many reports on the physical and chemical properties of DEHP. Nevertheless, due to experimental difficulties in connection with the investigation, the physical and chemical properties of this substance are still connected with some uncertainty. The present report is an attempt to provide a thorough review of the environmental fate and effects of DEHP.
In general, DEHP, is considered not readily biodegradable. After acclimation of the micro-organisms, the substance degrades relatively fast. Due to the ubiquitous use of DEHP, the micro-organisms in many treatment plants are expected to be acclimated to degrade DEHP, and in some laboratory tests using micro-organisms from already exposed treatment plants, the substance is found to be readily biodegradable. However mass balances on treatment plants based on chemical analyses demonstrate that due to the strong sorption of DEHP to particulate matter, only a minor degradation can be expected in practice. Moreover, based on tests simulating the conditions in the aquatic environment is considerably lower than in treatment plants. Finally, no biodegradation is expected in anaerobic conditions.
The bioaccumulation of DEHP has been investigated in numerous studies with aquatic organisms from various taxonomic groups. Bioconcentration factors from 40 to more than 100000 have been determined and it is therefore concluded that DEHP is very bioaccumulative.
It must be concluded that no acute or chronic lethality is found at concentrations below or at the water solubility limit (0.05 mg/l). However alterations or affects are found at biochemical level at low concentrations (NOEC = 0.0037 mg/l). Moreover, in laboratory test systems it is possible to test DEHP in concentrations considerably higher than the water solubility limit, as the substance forms stable emulsions because it is a liquid with a density close to 1 g/ml. At these conditions, acute lethal effects are found in concentrations of a few mg/l. The results can, however, not be extrapolated to environmental conditions, as such emulsions cannot be expected to form or persist in nature. Thus, in the environment no acute toxic effects are expected.
It is recommended that DEHP be classified "R53: May cause long-term adverse effects in the aquatic environment" because of its general low biodegradability in tests for ready biodegradability, its low biodegradability in practice in wastewater treatment plants and in the aquatic environment, its high potential for bio-accumulation and it low water solubility.
However, as no practice has been established concerning the evaluation of toxic effects at concentrations above the water solubility limit in relation to environmental hazard classification, it is recommended that it should be discussed and decided how to interpret these data. If these toxicity data are taken into account, an environmental hazard classification with "N;R51/53: Toxic to aquatic organisms, and may cause long term adverse effects in the aquatic environment" could be assigned.
As demonstrated in the present review, there are still some areas in the effects assessment of DEHP that deserve a further evaluation. It is therefore recommended that the following topics be considered for further investigations or research:
 | Alterations or effects at biochemical level. What are the reasons for these changes? They might be a result of the physical effects of the substance as e.g. the sorption to surfaces of the test species. What are the consequences of the changes on the organism, the population, or the ecosystem? |
| Estrogenic effects. Some of the phthalates have been shown to exert estrogenic effects. It should be further investigated and evaluated, whether this is also the case for DEHP. If so, what are then the ecological consequences? |
Author/ institution
Finn Pedersen, Water Quality Institute. Jørgen Larsen, Danish Technological Institute
This report is subsidised by the National Council for Recycling and Cleaner Technology
ISSN no. 0908-9195
ISBN no. 87-7810-650-8