Bis(2-ethylhexyl) phthalate

Toxicity to terrestrial plants

Description of key information

In available relevant studies on terrestrial plant toxicity no adverse effects of DEHP were observed. From the reliable key study (OECD 208), an unbounded NOEC of 130 mg/kg dwt is obtained. This value will be used for risk assessment and PNECsoil derivation.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

130 mg/kg soil dw

Additional information

In addition to the studies reviewed in EU-RAR (2008) up to now no new studies became available on toxicity to terrestrial plants. The re-evaluation of these studies has highlighted one key study (Diefenbach, 1998) where plant seedling and growth were studied in an acute toxicity test according to OECD 208 guideline and GLP procedure (limit test).

For the 3 species Triticum aestivum, Lepidum sativum and Brassica alba tested, DEHP showed no negative effect on seedling emergence or growth after 18 days exposure at 100 mg/kg dw (nominal concentration). No vehicle was used and the organic carbon content of the soil was reported to be <1.5%. If 1.5% is assumed this corresponds to approx. 2.6 % organic matter. When applying the normalisation equation on the NOEC (100 mg/kg) from this study a normalised NOEC of 130 mg/kg dwt is obtained. This value will be used for risk assessment and PNECsoil derivation.

These results are supported by three studies with both exposure via water, soil or air.

- Herring and Berring (1988) showed no effects on seedlings of Spinacia oleracea and Pisum sativum exposed to DEHP in soil, at the highest concentration. While authors also reported 40 and 50% reduction in seed germination for Spinacia oleracea and Pisum sativum respectively, when the seeds were soaked with water and DEHP at a nominal concentration of 0.1% (approximately 1,000 mg/l), no actual measured concentration is provided an nominal concentration is far above the apparent or even true water solubility of DEHP. Therefore, these data cannot be used in the risk assessment.

- In another study, Langebartels and Harms (1986) grew soybean and wheat cell cultures in nominal concentrations of DEHP up to 390 mg/l (added in methanol). No effect on the cell growth was observed. No effect was observed at 0.9 mg/l (the saturating concentration according to the authors).

- Then, Løkke and Rasmussen, (1983) investigated in a field experiment the effects of DEHP and DBP, when applied by spraying on the foliage of Sinapis alba and Brassica napus. No effect was observed at the maximum dosage of 8.75 µg/cm2 of DEHP. The authors concluded that DEHP seemed to have a very low mobility in plants. The authors also added droplets of pure DEHP, without solvents, on foliage. No adverse visible effect was observed from this treatment.

In these three studies, although (i) the test soil concentration was unclear, (ii) the effect concentrations in water were far above the solubility level, and (iii) exposure via the air is very unlikely considering the vapour pressure of DEHP in environmental conditions, no adverse effects were observed (exception Herring and Berring, 1988 with water exposure, but see argumentation above) and thus these results support the result from Diefenbach concluding that DEHP is not harmful to plants.