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Studies for terrestrial toxicity have been waived except for the toxicity to soil macroorganism. Toxicity of subtilisin to the earthworm has been investigated and no toxicity of subtilisin at concentrations up to 1000 mg TOS/kg d.w.soil, which was the highest dose applied, could be observed confirming the low toxicity of subtilisin.

Data waiving of the remaining terrestrial toxicity studies is based on following argumentation: Subtilisin has a very low Henry’s law constant (<10-4) and a low octanol-water partition coefficient (<0). Therefore, exposure to agricultural soil via sludge application as well as via aerial deposition is very low. Exposure to soil may occur if waste water is discharged of via septic tank. According to the EUSES calculations, less than 0.01% of enzymes entering a sewage treatment plant (STP) will bind to sludge. As enzymes are degradable at both aerobic and anaerobic conditions, a high rate of inactivation and degradation of subtilisin in soil is expected. Assuming a degradation rate in soil at the same level as degradation rate in surface water, i.e. a half life of 5 hours, calculations show that the risk characterisation ratio (RCR) for soil is 25% below the RCR for the surface water. Thus subtilisin applied to agricultural soils via sludge application do not present a risk to the soil compartment due to sludge application. Subtisin may potentially leach into the soil, if waste water is discharged to a septic tank, or if it is used in connection with septic maintenance. The chemical safety assessment based on the equilibrium partitioning method showed that subtilisin does not exhibit a risk to soil living organisms in these situations.

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