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Ecotoxicological information

Toxicity to terrestrial plants

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Description of key information

A 7-day short-term toxicity test using Lactuca sativa reported an EC50 for growth of 559 mg nonylphenol/kg (Hulzebos et al., 1993).  The key information for long-term effects to plant relates to the Domene et al., (2009) study where the most sensitive endpoint was a test on Lolium perenne with an EC10 based fresh weight of 574.8 mg nonylphenol/kg.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:
559 mg/kg soil dw
Long-term EC10, LC10 or NOEC for terrestrial plants:
574.8 mg/kg soil dw

Additional information

There were three reliable toxicity studies relating to six different species of terrestrial plants. Only one reliable short-term study was available where a 7-day test usingLactuca sativareported an EC50for growth of 559 mg nonylphenol/kg (Hulzebos et al., 1993). However, this result is more sensitive than the extended 14-day test in the same study where an EC50of 625 mg/kg is reported. The Key Study is provided by Domeneet al., (2009) as this study was highly reliable (Klimisch 1) and fulfilled the information requirements for a Robust Study Summary. The 50% effect concentrations in the Hulzeboset al., (1993) study are similar to the EC10results reported by Domeneet al., (2009). Effects on fresh weight inBrassica rapaandLolium perenneover a 15-day period resulted in calculated EC10s of 574.8 and 738.9 mg nonylphenol/kg, respectively. This suggests that dicotyledonous plants are more sensitive than monocotyledons to nonylphenol toxicity. A number of factors differ between the long-term exposures in the Hulzebos and Domene studies including (i) the species, (ii) the effect levels and (iii) the soil type. In particular, Domeneet al., (2009) used artificial soils (the preferred test medium for REACH testing) whereas Hulzeboset al., (1993) employed natural soil with the potential to introduce further uncertainty due to the variation in natural soil properties to the Hulzebos experiment. It is difficult to make direct comparisons between the two studies due to these variations but the results do suggest that plants are likely to be affected by nonylphenol in soils where concentrations exceed 559 mg nonylphenol/kg.Domeneet al,. (2009) also reports EC50values for seed germination inB. rapaandL. perenneof 8159.2 and 7500.7 mg/kg, respectively.

In summary, the reliable data present an inconsistent trend of the toxicity of nonylphenol to terrestrial plants, although the NOEC is expected to be around the 0.5g/kg level or more. Based on the arguments of data reliability, adequacy and sensitivity of test species, the key value for long-term plant exposure to nonylphenol and further hazard assessment is theL. perenneEC10of 574.8 mg/kg. These results indicate that nonylphenol is slightly toxic to some plants at the EC10protection level but not toxic at the EC50level. More generally, plants are less sensitive to nonylphenol than soil invertebrates. These data are suitable for use in the nonylphenol assessment.