Fatty acids, tallow, zinc salts

Sediment toxicity

Description of key information

FATTY ACIDS, C14 -18 AND C16 -18 -UNSATD., ZINC SALTS:

No toxicity data are available for Fatty acids, C14–C18 and C16-18-unsatd., zinc salts. Read-across to insoluble/ slightly soluble zinc substances is made, and the PNECs sediment as derived in the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 (see Appendix 1) are carried over to Fatty acids, C16-18, zinc salts.

ZINC:

Freshwater: chronic toxicity data are available for 7 species. Species mean NOECs used for PNEC derivation range from 201 to 1135 mg/kg dw. The species mean NOEC added range between 146 to 1101 mg/kg dw (after correction for background). In addition, two field studies are available for freshwater sediments. Lieber et al. 1996 have reported an overall NOECecosystem of 725 mg/kg d.w. added zinc. Burton et al. 2005 have observed minor effects on species richness and macroinvertebrate density at concentration of 119 mg/kg d.w. added zinc.

Marine water: chronic toxicity data are available for 2 marine species: the amphipod Melita plumulosa with a NOEC reproduction  of 730 mg/kg dw and the mangrove Avicennia marina with a NOEC emergence of 250 mg/kg dw. After background correction the NOEC values then become 490 mg/kg dw and 207.1 mg/kg dw for M. plumulosa and A. marina, respectively. No field studies were found for marine sediments.

Additional information

As no sediment toxicity data are available for Fatty acids, tallow, zinc salts or for the read-across substance Fatty acids, C16 - 18, zinc salts, a read-across to insoluble/ slightly soluble zinc substances is made as worst case approach in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5. As in the EU Risk Assessment Report (RAR) for Zinc stearate, it is assumed that upon dissolution Fatty acids, tallow, zinc salts are changed in part to ionic zinc and that only ionic zinc is determining biological activities. For a comprehensive overview of the toxicity of zinc, see the hazard assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 below.

ZINC:

Freshwater PNECadd, sediment

The assessment of the freshwater PNECadd, sediment for zinc is based on the chronic benthic toxicity data that were presented in the EU RAR for zinc (2008), complemented with four new high quality studies (species). From the knowledge available at the time of closure, a PNEC using an application factor of 10 on the lowest available NOEC value (488 mg/kg d.w.) was derived in the Risk Assessment Report. Because of the significant increase of information on chronic benthic toxicity, the PNEC from the RAR has been revised. Taking into account the weight of evidence provided by the elements discussed in the chemical safety report, it is considered that use of the HC5 from the SSD, using statistical extrapolation techniques, is justified for PNEC derivation, and that no additional assessment factor needs to be applied. Consequently, the PNEC is set at the level of the HC5 which is considered as protective for EU freshwater ecosystems: freshwater PNECadd, sediment = 117.8 mg/kg d.w. (equivalent to 25.9 mg/kg w.w.).

Marine PNECadd, sediment

The assessment of the marine PNECadd, sediment for zinc identified two long-term chronic toxicity studies. However, an EqP (using partitioning coefficients and a robust aquatic toxicity database) approach provided a reliable derivation for the marine benthic compartment. The resulting value is considered protective for EU marine ecosystems: marine PNECadd, sediment of 56.5 mg/kg d.w. (equivalent to 12.5 mg/kg w.w.).