Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

ZINC DILAURATE: 
acute toxicity to freshwater algae (standard test): EL50= 12.87 mg/L (extrapolated value) WAF in standard test medium (Pseudokirchneriella subcapitata)
chronic toxictiy to freshwater algae (standard test): EL10=3.73 mg/L WAF in standard test medium (Pseudokirchneriella subcapitata)
ZINC:
acute toxicity to freshwater algae: lowest IC50 0.136 mg Zn/L (Selenastrum capricornutum; single value) (neutral/high pH)
chronic toxictiy to freshwater algae: lowest NOEC 0.019 mg Zn/L (Pseudokircherniella subcapitata =Selenastrum capricornutum; geomean of 27 data)
chronic toxicity to marine algae: 12 species available which NOECs range between 0.0078 and 0.67 mg Zn/L (dissolved concentrations)

Key value for chemical safety assessment

Additional information

ZINC DILAURATE:

Acute freshwater toxicity tests of high quality and relevancy were performed according to OECD 201. Data are available for one species (P. subcapitata) which is the most sensitive species of all freshwater organisms. The EL50 value derived in standard test medium is taken as reference value for classification for acute effects (see below).

Chronic freshwater toxicity tests of high quality and relevancy were performed according to OECD 201. Data are available for one species (P. subcapitata) and are the only chronic data available for freshwater organisms. The EL10 value derived in standard test medium is taken as reference value for classification for chronic effects (see below).

In a growth inhibition test with P. subcapitata exposed to water accommodated fractions (WAF) of zinc dilaurate at loadings of 0.01, 0.1, 1 and 10 mg/L in standard test medium over a test period of 72 hours (Wenzel, 2013b), the calculated EL50 value for growth rate was 12.87 mg/L (extrapolated) while the EL10 was 3.73 mg/L, based on WAF loadings.

 

In a growth inhibition test with P. subcapitata exposed to water accommodated fractions (WAF) of Fatty acid, C16-18, zinc salts at loadings of 0.01, 0.1, 1, 10 and 100 mg/L in standard test medium over a test period of 72 hours (Wenzel, 2013a), the calculated EL10 value for growth rate was 3.31 mg/L (extrapolated) based on WAF loadings while the EL50 is expected to be > 100 mg/L based on WAF loadings. Thus, toxicity data from another structural analogue, i.e. zinc distearate - the zinc salt of a longer-chained fatty acid (C16-18), support the conclusion that zinc salts of fatty acids with a similar structural analogy, water solubility and zinc content are not toxic to algae at concentrations below relevant acute and chronic aquatic classification criteria.

Acute or chronic seawater tests were not performed with zinc dilaurate.

As only limited chronic toxicity data are available for zinc dilaurate, a read-across to insoluble/slightly soluble zinc substances is made, and the PNECs water as derived in the Chemical Safety Assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 are carried over to zinc dilaurate. For a comprehensive overview of the toxicity of zinc, see the hazard assessment of "Zinc" within the framework of Regulation (EC) No 1907/2006 in Appendix 1 of the CSR and cited in excerpts below.

ZINC:

Acute freshwater toxicity tests of high quality and relevancy performed according to standard protocol. Information is on 1 species which is in both the acute and chronic aquatic database on zinc the most sensitive. The lowest IC50 value is taken as reference value for classification for acute effect at neutral/high pH.

Chronic freshwater toxicity tests of high quality and relevancy according to standard protocol or equivalent. Data on 2 species, one of which the most sensitive of all freshwater organisms, second species is less sensitive.

Chronic seawater tests of high quality and relevancy according to standard protocol or equivalent. Data on 12 species, for which 3 species are in the low part of the species sensitivity distribution. One species of macro-algae is the second most sensitive of all seawater organisms.

acute toxicity to freshwater algae: lowest IC50 0.136 mg Zn/l (Selenastrum capricornutum; single value) (neutral/high pH)

chronic toxictiy to freshwater algae: lowest NOEC 0.019 mg Zn/l (Pseudokircherniella subcapitata =Selenastrum capricornutum; geomean of 27 data)

chronic toxicity to marine algae: 12 species available which NOECs range between 0.0078 and 0.67 mg/l (dissolved concentrations)