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Diethylhexyl phthalate

3. Can DEHP affect the environment?

  • 3.1 When is DEHP released?
  • 3.2 What happens to DEHP released to the environment?
  • 3.3 What levels of DEHP are expected near the sources?
  • 3.4 What are the effects of DEHP on the environment?
  • 3.5 What are the risks of DEHP to the environment?

3.1 When is DEHP released?

The source document for this Digest states:

3 ENVIRONMENT

Release of DEHP to the environment occurs during production, transport, storage, formulation and processing of PVC and non-polymers. Furthermore, plasticisers are not chemically bound to the matrix polymer in flexible PVC (or other materials). Therefore the plasticiser will to some extent be lost from the finished article during its use and after its final disposal.

DEHP enters the environment mainly via direct releases to air and waste water, from sewage sludge and from solid waste. In air, DEHP may occur both in vapour phase and as solid particles. The nature of these particles can be either aggregated pure DEHP or polymer particles containing DEHP. Particles formed by weathering of polymer products probably represent an important route of DEHP distribution. It is estimated that around 800 industrial sites in EU use DEHP or preparations containing DEHP. Releases from these sources are expected to cause higher local exposure.

An estimation of the contribution to the total emissions of DEHP from different life-cycle stages is presented in Table 3.1.

Source & ©: ECB,
 "Bis-(2-Ethylhexyl) Phthalate, DEHP), Summary Risk Assessment report" , 2008. p.6.

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3.2 What happens to DEHP released to the environment?

The source document for this Digest states:

Environmental fate

Photodegradation of DEHP (reaction with OH radicals) is important in the atmosphere (T½ = 1 day) but is assumed to be of little importance in water and soil. DEHP does not hydrolyse in water. The biodegradation of DEHP is varying in available studies. Based on the results of standard biodegradation test DEHP is readily biodegradable. Experimental data indicates a biodegradation half-life for DEHP in surface water of 50 days, and 300 days in aerobic sediment. Anaerobic conditions and low temperature further reduce the degradation rate. Results from degradation studies of DEHP in agricultural soil are variable, but indicate moderate to low biodegradation rates. MEHP is the primary biodegradation product of DEHP. With a log Kow of 7.5, DEHP is expected to be strongly adsorbed to organic matter. DEHP is therefore expected to be found in the solid organic phase in the environment. The log Koc for DEHP is 5.2 L/kg. Hence, DEHP will be strongly adsorbed to the sludge in sewage treatment plants. DEHP has a vapour pressure of 3.4 . 10-5 Pa (at 20 to 25°C), which indicate a low evaporation rate from its pure state, and a Henry’s law constant of 4.4 Pa m3/mol, indicating a moderate evaporation from a pure water solution (‘semi-volatile’).

DEHP is found to bioaccumulate in aquatic organisms, and the highest BCF values are observed for invertebrates e.g. 2,700 for Gammarus (BCFfish 840). This indicates that uptake via the food chain might be an important exposure route (secondary poisoning). BCF, as well as monitoring data for different trophic levels, indicate that DEHP does not bio-magnify. This may in part be due to a more effective metabolisation rate in higher organisms.

Due to its high affinity to organic matter only a limited bioaccumulation of DEHP in plants is expected. The environmental studies confirm this with BCF ranging between 0.01 and 5.9. For earthworms a BCF of 1, based on experimental results and modelled (EUSES) data, has been used in the risk assessment.

The large amount of DEHP accumulated in the technosphere indicates a considerable potential for release of DEHP and of subsequent formation and distribution of MEHP. However, the formation rate and fate of MEHP in the environment is not known. MEHP causes reproductive toxicity in studies on mammals. There are no other data on ecotoxicological properties of MEHP available.

Source & ©: ECB,
 "Bis-(2-Ethylhexyl) Phthalate, DEHP), Summary Risk Assessment report" , 2008. p.6-7.

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3.3 What levels of DEHP are expected near the sources?

The source document for this Digest states:

Environmental concentrations

The methods in the Technical Guidance Document were used to estimate concentrations in water, sediment, air, soil and biota. In addition a large number of monitoring studies on DEHP are available, with recent studies being much more reliable than earlier ones where contamination often was a problem.

Water

The levels of reported concentrations of DEHP in river waters vary from below the detection limit up to 21 µg/l, with industrial and highly urbanized areas having the higher levels. In lake water, the concentrations were lower. The difference is probably due to the higher levels of suspended matter in flowing waters. In marine surface waters in Norway the concentration of DEHP was below 0.1 µg/l except for one sampling station close to a municipal STP where the concentration was approx. 0.4 µg/l. Measured concentrations of DEHP in surface sediment from rivers and lakes situated in industrial or urban areas where no DEHP using industries were specified, ranged between 0.04 and 21 mg/kg dwt. Close to sites processing materials containing DEHP, much higher concentrations have been found.

The regional PEC in the risk assessment was based on monitoring data from a highly industrialized and densely populated area, and set to 0.8 µg/l.

The local PECs were estimated using the EUSES model and are shown in Table 3.2.

Sewage treatment plants

In monitoring studies on different municipal STPs in Sweden, Denmark, Norway, and Germany measured concentrations in untreated wastewater (influent) varied between 4-250 µg/l. In treated wastewater (effluent) DEHP concentrations varied between 0.07 and 28 µg/l with removal rates mostly in the range 90 – 99%. However, in a few cases removal rates were lower, in one case only 40%. In monitoring studies on DEHP in municipal STP sludge the concentrations vary between 0 and 661 mg/kg dwt in sludge from Sweden, Denmark, Norway, the Netherlands and Germany. There are no measurements available on sludge from industrial STPs.

The local PECs for STP effluent were estimated using the EUSES model and ranged up to 20 mg/l for production and up to 1.3 mg/l for formulation and processing.

Atmosphere

DEHP has been found in gas phase, solid phase (particles), and in water phase (rain water) of air samples. In some of the studies it is not clear which phases that have been analysed. In monitoring studies considered to represent regional scenarios, concentrations of DEHP between 0.3 and 300 ng/m3 have been measured. The highest values were achieved on sampling sites in urban or unspecified polluted areas.

Soil

The PECs for agricultural soil were estimated using the EUSES model and are shown in Table 3.3.

Table33

Secondary poisoning

The PEC oral-aquatic is calculated by multiplying the bioconcentration factor (BCF) with PECsurface water (see Table 3.2). The BCF for fish used in this assessment is 840. However, it has been shown that the BCF for fish decreases with increasing DEHP concentrations in water when the water solubility is exceeded. Therefore, the water solubility of 3 µg/l is used as a limit for the calculation of PECoral aquatic fish, i.e. when a PECsurface water exceeds the water solubility the water solubility is used for calculating PECoral aquatic. The same approach is used for the calculation of PECoral aquatic zooplankton using a wet weight BCF of 2,700. This approach may underestimate the concentration in biota in highly contaminated areas since it can be assumed that in such cases the absorption of DEHP from food becomes increasingly important. The highest measured concentration in fish from an extensive study in Austria was 2.6 mg/kg wwt. This value compares quite well with the concentration derived when multiplying BCF with water solubility. The concentration of DEHP in water was not measured in the Austrian study. For PECoral aquatic mussels the calculated PECsurface water is used. This is based on a study where no difference in BCF was seen at DEHP concentrations of 4.6 and 46 µg/l respectively. Furthermore, since mussels are filter feeders it is assumed that the non-dissolved and particle bound fractions are bioavailable. Local PECoral worm is not calculated for the production sites since STP sludge from production sites is not used as fertiliser.

The calculated PECs are shown in Table 3.4.

Source & ©: ECB,
 "Bis-(2-Ethylhexyl) Phthalate, DEHP), Summary Risk Assessment report" , 2008. p.7-9.

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3.4 What are the effects of DEHP on the environment?

The source document for this Digest states:

3.1 EFFECTS ASSESSMENT

Aquatic compartment (incl. sediment)

Several reliable short-term and long-term studies on effects of DEHP on aquatic organisms exist. There are no studies indicating effects on organisms only exposed to DEHP via water, and at concentrations below the water solubility. However, effects have been shown on fish exposed to DEHP via food. Therefore a NOEC for fish of 160 mg/kgfood has been determined. Studies with sediment organisms showed no effects at 1,000 mg/kg dwt, the highest tested concentration.

Effects on microorganisms

Only one study, on respiration in activated sludge, is considered valid for the risk assessment of DEHP in STPs. No effects were observed at the highest tested concentration, 2,007 mg/L (NOEC).

Atmosphere

No studies exist from which a PNECatmosphere could be derived.

Terrestrial compartment

There are four valid tests with soil organisms, from three trophic levels, all showing no effects. From these studies a NOEC ≥ 130 mg/kg dwt is obtained

Secondary poisoning

For exposure via the food a NOEC of 33 mg/kgfood for mammalian predators is determined, based on studies showing testicular damage in rats at 4.8mg/kg/d in a three generation reproductive toxicity study. For effects on bird reproduction a NOEC of 1,700 mg/kgfood is calculated.

Source & ©: ECB,
 "Bis-(2-Ethylhexyl) Phthalate, DEHP), Summary Risk Assessment report" , 2008. p.9-10.

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3.5 What are the risks of DEHP to the environment?

The source document for this Digest states:

3.2 RISK CHARACTERISATION

As a realistic worst case, the PECs from generic scenarios based on default emission data have been selected except for production where site-specific data has been used. Reliable, relevant and adequate measured data for emissions is only available for a limited number of sites using DEHP (representing less than 5% of the total DEHP use). Where such data is available, it has been used to make local scenarios for the reporting sites, but has not been deemed adequate for extrapolation to all other sites using DEHP (in the order of 800 sites).

Aquatic compartment (incl. sediment)

Due to lack of effects at or below the “apparent” water solubility no PNEC can be specified. The conclusion is that there is no concern for aquatic species exposed via the water phase.

Due to its lipohilic nature and slow degradation under anaerobic conditions DEHP is often found in high concentrations in sediment. The PNEC (> 100 mg/kg dw) is derived from a study where no effects were seen at the highest tested concentration and the other sediment toxicity studies indicates even lower sensitivity. Therefore the actual PNEC may be higher. Repeating the tests at higher test substance concentrations than those used is not proposed because several studies are already available for DEHP and because of the difficulties associated with testing very high concentrations of a substance. Further emission information could be requested to refine the exposure assessment, but since the same scenarios that have PEC/PNEC ratios > 1 for sediment dwelling organisms, also have PEC/PNEC ratios > 1 for the food chains based on aquatic organisms, the risk reduction strategy will have to address the emissions in these scenarios anyway. Further studies are therefore not requested at this point.

Therefore for the use areas with a PEC/PNEC > 1, a conclusion (i) "on hold" is reached: There is a need for further information and/or testing, because further refinement of the assessment may remove some concern. However implementation of risk management measures to address the risks identified for other environmental spheres will eliminate the need for further information on sediment dwelling organisms.

This conclusion applies to the processing of polymers containing DEHP and for formulation of lacquers, paints, printing inks, sealants and/or adhesives containing DEHP. The scenarios that give concern are generic scenarios based on default emission data. There is no concern for the limited number of sites that have reported measured emission data. The production sites with PEC/PNEC ratios above 1 have all ceased production of DEHP.

Atmosphere

There are no data indicating risk for the atmospheric compartment.

Terrestrial compartment

The PNEC (> 13 mg/kg dwt) is derived from a study where no effects were seen at the highest tested concentration and the other soil toxicity studies indicates even lower sensitivity, thus the actual PNEC may be higher. Repeating the tests at higher test substance concentrations than those used is not proposed because several studies are already available for DEHP and because of the difficulties associated with testing very high concentrations of a substance. Further emission information could be requested to refine the exposure assessment, but since the same scenarios that have PEC/PNEC ratios > 1 for soil organisms, also have PEC/PNEC ratios > 1 for the food chains based on terrestrial organisms, the risk reduction strategy will have to address the emissions in these scenarios anyway. Further studies are therefore not requested at this point.

Therefore a conclusion i on hold is reached: There is a need for further information and/or testing, because further refinement of the assessment may remove some concern. However implementation of risk management measures to address the risks identified for other environmental spheres will eliminate the need for further information on soil organisms

This conclusion applies to the processing of polymers containing DEHP and for formulation of printing inks, sealants and/or adhesives containing DEHP. The scenarios that give concern are generic scenarios based on default emission data. There is no concern for the limited number of sites that have reported measured emission data.

Secondary poisoning

The PNECoral for DEHP in fresh food is 3.3 mg/kg for mammalians, 17 mg/kg for birds, and 16 mg/kg for fish. In this risk assessment we assume that mammalians eat fish, birds eat mussels, and fish eat invertebrates in food chains based on aquatic exposure to DEHP. In the terrestrial food chain mammalians are assumed to eat DEHP exposed earthworms.

Food chains based on aquatic organisms

The PEC/PNEC ratios are below 1 for mammalians eating fish, and for fish eating invertebrates for all scenarios. For birds eating mussels the ratio is above 1 for 6 scenarios, two of which are production sites that have now ceased production of DEHP. The generic, but not the site-specific, local risk characterisation for plastisol spread coating without air cleaning and sealants/adhesives formulation gave PEC/PNEC ratios > 1.

Therefore the conclusion is that releases from sites processing polymers containing DEHP and sites formulating printing ink, sealants and/or adhesives containing DEHP, may cause adverse effects in food chains based on aquatic organisms. The scenarios that give concern are generic scenarios based on default emission data. There is no concern for the limited number of sites that have reported measured emission data.

Food chains based on terrestrial organisms

For mammalians eating earthworms the PEC/PNEC ratios are above 1 for some sites processing polymers containing DEHP and formulating lacquers, paints, printing ink, sealants and/or adhesives containing DEHP. Therefore the conclusion is that releases from these sites may cause adverse effects in food chains based on terrestrial organisms. The scenarios that give concern are generic scenarios based on default emission data. There is no concern for the limited number of sites that have reported measured emission data.

Source & ©: ECB,
 "Bis-(2-Ethylhexyl) Phthalate, DEHP), Summary Risk Assessment report" , 2008. p.10-12.

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