Phenol, 4-nonyl-, branched

Toxicity to soil macroorganisms except arthropods

Description of key information

The Johnson et al (2005) short-term LC50 of 88.6 mg nonylphenol/kg  for Eisenia andreii survival meets reliability ownership and adequecy requirements for REACH.  The study uses the preferred test species and the preferred test medium, artificial soil.  The long-term study of Domene et al (2009) followed international OECD and ISO protocols, uses standard test species and achieves the highest Klimisch rating.  Long-term exposure of Enchytraeus crypticus reported an EC10 of 24 mg nonylphenol/kg.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

88.6 mg/kg soil dw

Long-term EC10, LC10 or NOEC for soil macroorganisms:

24 mg/kg soil dw

Additional information

Only one reliable study was available for short-term exposure to soil macro-organisms except arthropods and this was the Key Study by Johnsonet al., (2005). The preferred earthworm species,Eisenia andreiiwas exposed to nonylphenol for 14 days with a reported NOEC and LOEC based on survival of 32 and 100 mg/kg, respectively. ENVIRON UK Ltd calculated an LC₅₀of 88.6 mg nonylphenol/kg for the survival data using Probit statistical analysis. The derivation of an LC₅₀means the macro-invertebrate data are more easily comparable with the other short-term study for plants (see Hulzeboset al., 1993), where macro-invertebrates appeared to be more sensitive than plants.

Two studies representing three endpoints were reported for long-term macro-invertebrate exposures to nonylphenol resulting in NOEC or EC10 values ranging from 24 to 100 mg nonylphenol/kg. Both Johnsonet al., 2005 and Domeneet al., 2009 carried out 8-week earthworm (Eisenia andreii) reproduction studies using nonylphenol spiked artificial soil exposures. The Johnsonet al., 2005 studied did not record any effects on reproduction at the highest concentration tested (NOEC = 100 mg/kg) but the Domeneet al., 2009 study statistically derived a more robust EC₁₀of 55.8 mg/kg. Domeneet al., 2009 also studied reproduction inEnchytraeus crypticusand statistically derived an EC₁₀of 24 mg nonylphenol/kg. TheE. crypticusduration was 4 weeks and slightly shorter in duration than the standard 6-week duration of the standard ISO Guideline but this is still considered to be acceptable as this smaller enchytraeid species’ breeding cycle was completed.

In addition, Domene et al., 2009 compared the standard toxicity tests between OECD artificial soils and two natural soils. In the earthworm tests where reproduction in the OECD was affected at the 10% level leading to an EC₁₀of 55.8 mg/kg, the loamy sand soil from dry grassland affected reproduction at 43.1 mg/kg (more sensitive) but the agricultural loamy soil was less sensitive with an EC₁₀of 63.6 mg/kg. However, when the enchytraeid study was compared, both natural soils reported far less sensitive values than the OECD soil; 455.8 and 197.2 mg/kg compared to the EC₁₀of 24 mg/kg in the OECD soil. The inconsistency in trends between natural and artificial soils means that the artificial soils are preferred for use in this REACH dossier to ensure studies are comparable where possible.

The long-term study of Domene et al., (2009) forEnchytraeus crypticuswith an EC₁₀of 24 mg nonylphenol/kg is the key study for this endpoint and is supported by the less sensitive long-term and short-term earthworm studies.