Fatty acids, tallow, zinc salts

Endpoint summary

Additional information

Based on physico-chemical properties, the main target compartments for the environmental distribution of Fatty acids, tallow, zinc salts would be soil and sediment. However, as the substance is readily biodegradable and has potential to adsorb (log Koc > 3), it is expected to be eliminated in sewage treatment plants to a high extent. Release to surface waters, and thereby exposure of sediment, is therefore very unlikely. In soil, the substance is expected to be rapidly removed via biodegradation. The transport and distribution of zinc has been comprehensively reviewed in the EU Risk Assessment Report for Zinc metal (ECB, 2008).

Transport and distribution of zinc

For metals, the transport and distribution over the different environmental compartments e.g. the water (dissolved fraction, fraction bound to suspended matter), soil (fraction bound or complexed to the soil particles, fraction in the soil pore water, etc.) is described and quantified by partition coefficients. Partition coefficients for zinc in freshwater have been reviewed in the EU Risk Assessment Report for Zinc metal (ECB, 2008). Based on the experimental evidence, a partition coefficient for the distribution between solid particulate matter and water (log Kpsusp) of 5.04 has been defined for EU waters and was used throughout the risk assessment.

The partition coefficient for the distribution between sediment and water (Kpsed) was estimated in the Risk Assessment Report from that for particulate matter, as follows: Kpsed= Kpsusp/ 1.5, based on the average difference in concentrations of zinc and other metals in both media. For zinc this results in a Kpsed of 73000 L/kg or log Kpsed 4.86 (ECB, 2008).

These partition coefficients based in the Risk Assessment Report have been used in other legislative processes in the EU (e.g. the water framework directive) and will also be used for REACH.

For marine water, a partition coefficient water/suspended matter of 6010 L/kg (log value 3.78) has been derived.

For soil, a solids-water partitioning coefficient of 158.5 L/kg (log value 2.2) was determined experimentally on 11 American soils. This value was used in the risk assessment for zinc.

Literature data on partition coefficients are entered under Section 5.6. of the technical dossier.

Conclusion:

The main target compartment of Fatty acids, tallow, zinc salts is expected to be soil, in which the substance will adsorb to solid organic matter. The organic moiety will be rapidly biodegraded. Remaining zinc has also potential to adsorb to solid particles; however, its partitioning strongly depends on the environmental conditions.