Fatty acids, C9-13-neo-, zinc salts

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

Marine water

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

no hazard identified

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Read-across approach

In the assessment of the ecotoxicity of Fatty acids, C9-13-neo-, zinc salts, a read-across approach from data for the metal cation and the organic anion is followed. This read-across strategy is based upon the assumption that upon release to the environment and dissolution in aqueous media, Fatty acids, C9-13-neo-, zinc salts will dissociate and only be present in its dissociated form, i.e. as zinc cation and C9-13-neo carboxylate anions.

Upon dissolution in water, it is indeed predicted that metal carboxylates dissociate completely into the metal cation and the organic anion at environmentally relevant conditions. No information is available on the stability constants of Fatty acids, C9-13-neo-, zinc salts, but predictions of stability of other zinc carboxylates (Zn propionate, Zn valerate, Zn isovalerate and Zn benzoate)in a standard ISO 6341 medium (2 mMCaCl₂, 0.5 mM MgSO₄, 0.77 mM NaHCO₃ and 0.077 mM KCl, pH 6 and 8) clearly show that monodentate ligands such as carboxylic acids have no potential for complexing zinc ions in solution (Visual minteq. Version 3.0, update of 18 October 2012. http://www2.lwr.kth.se/English/OurSoftware/vminteq/index.html).

The fate and behaviour (e.g. partitioning) in the environment for Zn²⁺ and C9-13-neo carboxylate anions are predicted to be significantly different from each other, resulting in a different distribution over the environmental compartments (water, air, sediment and soil). Because the relative exposure to both constituent ions is hence predicted to be different from the original composition of Fatty acids, C9-13-neo-, zinc salts, data for the ecotoxicological properties of Fatty acids, C9-13-neo-, zinc salts as such are considered less relevant for effects and risk assessment and a read-across approach to separate data for both the zinc cation and Fatty acids, C9-13-neo- is preferred.

For most metal-containing compounds, it is the potentially bioavailable metal ion that is liberated (in greater or lesser amounts) upon contact with water that is the moiety of ecotoxicological concern. The solubility of Fatty acids, C9-13-neo-, zinc salts (see IUCLID section 4.8 or chapter 1.3 of the CSR) is above the range of effects concentrations for dissolved zinc in the aquatic environment (lowest acute and chronic reference values: 136 and 19 µg Zn/L, respectively, PNECfreshwater for Zn = 20.6 µg Zn/L) and therefore ecotoxicity data for soluble zinc salts can be directly used in a read-across approach for Fatty acids, C9-13-neo-, zinc salts. As a conservative approach also the ecotoxicological properties of the carboxylic acid are considered.

According to the REACH Guidance on information requirements and chemical safety assessment, chapter B.8 Scope of exposure assessment, an environmental exposure and risk assessment is mandatory for a substance if it is classified as hazardous to the aquatic environment or if it has another classification and an aquatic PNEC can be derived. The threshold for PNEC derivation is not reported in the guidance, and was set at the limit test concentration for acute toxicity tests with fish, daphnids and algae, i.e. 100 mg/L. Therefore if a substance is not classified as dangerous for the aquatic environment, but meets the criteria for at least one of the other hazard classes or categories and has L(E)C50 values < 100 mg/L, it was still considered for the environmental exposure assessment.

For Fatty acids, C9-13-neo, zinc salts, both the Zn²⁺ ion and Fatty acids, C9-13-neo- are considered for the environmental exposure and risk assessment because both moieties are classified as hazardous to the aquatic environment (as Aquatic Acute 1, Aquatic Chronic 1 and as Aquatic Chronic 3, respectively). In case both moieties require a risk assessment, the dose additivity approach is used to explain the ecotoxicological effects of the metal carboxylate based on the data for the individual moieties. As stated in a toxicity assessment of chemical mixtures opinion for the European Commission (Scientific Committee on Consumer Safety (SCCS), Scientific Committee on Health and Environmental Risks (SCHER), and Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR). 2011. Preliminary opinion on Toxicity and Assessment of Chemical Mixtures; http://ec.europa.eu/health/scientific_committees/environmental_risks/docs/scher_o_155.pdf), the dose/concentration addition method should be preferred over the independent action approach if no mode of action information is available.

Ecotoxicological data for Fatty acids, C9-13-neo-, zinc salts are only available for a standard OECD 201 algae test with Pseudokirchneriella subcapitata (Cheshire EcoSolutions, 2013). The algae test was selected because the zinc moiety is predicted to be the driver for toxic effects of Fatty acids, C9-13-neo-, zinc salts in the environment and algae are the most sensitive aquatic organisms to zinc.

Only few ecotoxicity data are available for Fatty acids, C9-13-neo or its salts. Based on the similarities in structure, physical-chemical properties, environmental fate and toxicity between Fatty acids C9-13-neo and neodecanoic acid (C10-neo acid; CAS 26896-20-8), data for neodecanoic acid were therefore selected for the read-across approach. This is consistent with the grouping approach followed by the US EPA HPV programme for even a wider range of neo acids (C5-C28; http://www.epa.gov/hpvis/rbp/Category_Neoacids%20C5-28_Web_April%202009.pdf).

Read-across to the corresponding toxicity data for effect of zinc and neodecanoic acid on algae growth rate and the dose additivity approach (based on the assumption of complete dissolution and a worst-case zinc content of 17% in Fatty acids, C9-13-neo-, zinc salts) results in a predicted ErC50 for Fatty acids, C9-13-neo-, zinc salts that is lower than the experimentally derived ErC50 for this substance (Eqn. 1; Table 1).

EC50ZnNeo = 1 / {(weight % Zn / EC50 Zn) + (weight % Neo / EC50 Neo)} (Eqn. 1)

It is therefore concluded that the read-across approach to the zinc and neodecanoic acid is conservative. The zinc moiety is the main driver for toxic effects of Fatty acids, C9-13-neo-, zinc salts to aquatic organisms and the ecotoxicity data for Fatty acids, C9-13-neo (as predicted from neodecanoic acid) do not add significantly to the predicted toxicity for Fatty acids, C9-13-neo-, zinc salts.

Table 1: Acute toxicity data for effects of fatty acids, C9-13-neo-, zinc salts and its moieties to aquatic organisms (only most sensitive species per trophic level).

Trophic level	Endpoint	Fatty acids, C9 -13 -neo-, zinc salts (CAS: 92044 -84 -3)	Neodecanoic acid (CAS: 26896 -20 -8)	Zinc ion
Algae	72h ErC50	1.25 mg/L (experimental,  Pseudokirchneriella subcapitata ); 0.80 mg/L (based on read across to zinc only); 0.79 mg/L (based on read across to both zinc and neodecanoic acid)	>100 mg/L (Pseudokirchneriella subcapitata)	0.136 mg Zn/L (Pseudokirchneriella subcapitata)
Fish	96h LC50	No experimental data	> 100 mg/L (Oncorhynchus mykiss)	0.169 mg Zn/L (Oncorhynchus mykiss)
Aquatic invertebrates	48h EC50	No experimental data	> 1000 mg/L (Daphnia magna)	0.147 mg Zn/L (Ceriodaphnia dubia)

Conclusion on classification

The classification as hazardous to the aquatic environment of Fatty acids, C9-13-neo-, zinc salts is based on a weight of evidence approach, taking into account the data for Fatty acids, C9-13-neo-, zinc salts itself and the classification of its moieties (zinc and Fatty acids, C9-13-neo):

• Only an acute ErC50 value for the effect of Fatty acids, C9-13-neo-, zinc salts on algae growth rate is available (ErC50 of 1.25 mg/L; Cheshire EcoSolutions, 2013). Algae are considered as the most sensitive aquatic organisms for toxicity of Fatty acids, C9-13-neo-, zinc salts because i) algae are the most sensitive aquatic organisms for zinc and ii) Fatty acids, C9-13-neo are far less toxic to aquatic organisms compared to zinc. Therefore it is concluded that data on toxicity of Fatty acids, C9-13-neo-, zinc salts to fish and aquatic invertebrates are not critical for classification and the value of 1.25 mg/L is taken forward as the acute Exotoxicity Reference Value (ERVacute) for this substance. This ERVacute is > 1 mg/L and therefore does not result in an acute 1 classification for Fatty acids, C9-13-neo-, zinc salts.

• Assessment of chronic effects based on the acute data for Fatty acids, C9-13-neo-, zinc salts results in a chronic 2 classification for a substance that is not rapidly degradable. The zinc moiety is identified as the main driver for toxic effects of Fatty acids, C9-13-neo-, zinc salts to aquatic organisms and the ecotoxicity of Fatty acids, C9-13-neo is predicted not to add significantly to the predicted toxicity for Fatty acids, C9-13-neo-, zinc salts. The concept of “degradability” was developed for organic substances and is not applicable to inorganic substances like zinc. As a surrogate approach for assessing “degradability”, the concept of “removal from the water column” was developed to assess whether or not a given metal ion would remain present in the water column upon addition (and thus be able to exert a chronic effect) or would be rapidly removed from the water column. In this concept, “rapid removal” (defined as >70% removal within 28 days) is considered as equivalent to “rapidly degradable”. Under IUCLID section 5.6, the rapid removal of zinc from the water column is documented. Consequently, zinc is considered as equivalent to being ‘rapidly degradable” in the context of classification for chronic aquatic effects. Following this line of reasoning, it can be concluded that the acute toxicity data would not justify a chronic classification for Fatty acids, C9-13-neo-, zinc salts.

• The substance Fatty acids, C9-13-neo-, zinc salts has no official Annex VI classification and will dissociate into zinc and Fatty acids, C9-13-neo ions after dissolution in water and hence can be regarded as a mixture of both constituent ions. Zinc has an official Aquatic Acute 1 and Aquatic Chronic 1 classification (M factor 1; Annex VI of CLP Regulation EC No 1272/2008)), while Fatty acids, C9-13-neo are classified as Aquatic Chronic 3. For the reasons mentioned above, the zinc constituent is however considered as equivalent to being ‘rapidly degradable” in the context of classification for chronic aquatic effects. Considering this, in combination with the chronic ecotoxicity reference value for zinc of 19 µg/L, the classification of the zinc constituent for chronic aquatic effect should be “Aquatic Chronic 2”, rather than the previously mentioned official Aquatic Chronic 1 classification. Taking into account the weight of zinc in Fatty acids, C9-13-neo-, zinc salts (15-17%), the summation method results in an Aquatic Chronic 3 classification for Fatty acids, C9-13-neo-, zinc salts.

It is concluded that an Aquatic Chronic 3 classification for hazards to the aquatic environment is appropriate for Fatty acids, C9-13-neo-, zinc salts.