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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Adequate reliable measured and estimated data exists for toxicity to algae of constituents of Alchisor TAL 123 (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol). While adequate reliable measured and estimated data exists for toxicity to algae of constituents of Alchisor TAL 123, the most reliable and relevant study result for classification has been identified as the Alchisor TAL 123 (read-across source substance) study (ENVIRON, 2012), which reports a 72 -hr NOEC based on cell count of 3.75 mg/L WAF. However, while loading rate studies can be used for classification, they cannot be used for PNEC derivation (REACH endpoint guidance, chapter 7b). Therefore, in a protective approach the most sensitive study result from across the three constituents has been identified and used to address the hazard endpoint in question. The most sensitive study result from across the three constituents has been identified as a reliable study with dodecan-1-ol (Huls, 1997) which reports a nominal 72-hr NOEC based on growth of 0.085 mg/L.  This value will be taken as the toxicity in aquatic algae endpoint for Alchisor TAL 123.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.33 mg/L
EC10 or NOEC for freshwater algae:
0.085 mg/L

Additional information

Adequate reliable measured and estimated data exist for toxicity to algae of constituents of Alchisor TAL 123: Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol. Study data, where available, for each constituent has been evaluated and considered together. The most reliable and relevant study result for classification has been identified as the Alchisor TAL 123 (read-across source substance) study (ENVIRON, 2012), which reports a 72 -hr NOEC based on cell count of 3.75 mg/L WAF. However, while loading rate studies can be used for classification, they cannot be used for PNEC derivation (REACH endpoint guidance, chapter 7b). Several reliable (Klimisch 1 or 2) toxicity studies for algae have been conducted for components of Alchisor TAL 123 (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol) and are included in this dossier. The reliable studies included for each Alchisor TAL 123 constituent are briefly described below. In a protective approach the most sensitive study result from across the three constituents was identified and used to address the hazard endpoint in question.

Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%)

Three reliable (Klimisch 1) toxicity study results for algae were available to represent C9-C14 aliphatics (2-25% aromatics). The Shell Research and Technology Centre (1995) conducted a GLP compliant OECD 201 study with low aromatic white spirit (identified as hydrocarbons, C10-C13, n-alkanes, isoalkanes, cyclics, aromatics (2-25%)) where Raphidocelis subcapitata (new name: Pseudokirchnerella subcapitata), was exposed for 72 hrs. The 72 -hr EL50 for Raphidocelis subcapitata was 4.6-10 mg/l (WAF) for growth and biomass. The 72-hr NOELR was 3 mg/L, based on biomass and growth. The 72-hr EL50, based on biomass and growth was estimated to be 10-100 mg/L. Exxon Biomedical Sciences, Inc (2005) conducted a GLP compliant OECD 201 study with low aromatic white spirit (identified as hydrocarbons, C9-C12, isoalkanes, cyclics, aromatics (2-25%)) where Pseudokirchnerella subcapitata was exposed for 72 hrs. The 72-hr NOELR and NOEC, based on growth and biomass, were 0.76 and 0.16 mg/L, respectively. Biomass was more sensitive than growth measurements and resulting EL50and EC50, based on biomass, were 2.3 and 0.53 mg/L, respectively. The Shell Research and Technology Centre (1997) conducted GLP compliant OECD 201 study with low aromatic white spirit (identified as hydrocarbons, C10-C13, C8-C12 & C9-C12, n-alkanes, isoalkanes, cyclics, aromatics (2-25%)) where Raphidocelis subcapitata (new name: Pseudokirchnerella subcapitata) was exposed for 72 -hrs. The 72 -hr EL50 for Raphidocelis subcapitata was 4.6-10 mg/l (WAF) for growth and biomass. The 72-hr NOEL was 0.22 mg/L, based on biomass and 1 mg/L, based on growth. The 72-hr NOEC of 0.22 mg/L is considered the most sensitive study result for long-term toxicity of Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%) to algae.

Undecan-1-ol

No measured data was available for the toxicity of undecan-1ol to algae. However, using a read-across approach, Fisk et al., (2009) presented predicted values for toxicity of undecan-1-ol to using read across and expert judgment with validation based on measured data across the data set. Examination of the available measured data across the long chain alcohols category suggests that algal EC50 values are of the same order of magnitude, or slightly lower, than theDaphniaEC50 values. However, there is always uncertainty in such read-across, so the estimated algal EC50 has been stated as a range of 0.1-1 mg/L.

Dodecan-1-ol

Three reliable (Klimisch 2) toxicity studies for algae were available for dodecan-1-ol. Huls (1997) conducted a GLP compliant OECD 201 study where Scenedesmus subspicatus (new name: Desmodesmus subspicatus) was exposed for 72 hours. The 72-hr EC50 and NOEC, based on biomass and growth are 0.33 mg/L and 0.085 mg/L respectively. Henkel (1994) conducted a GLP complaint OECD 201 study where Scenedesmus subspicatus (new name:Desmodesmus subspicatus) was exposed for 72 hours. The 72 hr EC50, based on growth, is 2.6 mg/L and 0.62 mg/L based on biomass. The 72-hr NOEC, based on biomass, is 0.40 mg/L. Guhl (1992) conducted a GLP complaint OECD 201 study where Scenedesmus subspicatus (new name: Desmodesmus subspicatus) was exposed for 96 hours. The 96-hr EC50 and NOEC, based on biomass and growth, are 0.97 mg/L and 0.30 mg/L, respectively.

Alchisor TAL 123

ENVIRON International Corporation (2012) conducted a study to determine the chronic toxicity of the soluble components of the chemical Alkenes, C11-12, hydroformylation products, low boiling (Trade name Alchisor TAL 123) to the green algae Pseudokirchneriella subcapitata (P. subcapitata) in a standard reconstituted algae culture medium over 72 hours. A range-finding test was conducted in March 2012. Results of the range-finding test demonstrated greater than 82 percent reduction in algal growth in the nominal 100 mg/L Water Accommodated Fraction (WAF) exposure. A definitive test was conducted from June 19, 2012 to June 22, 2012 with WAF preparations of 3.75, 7.5, 15, 30, and 60 mg/L nominal loading rates of Alkenes, C11-12, hydroformylation products, low boiling. These treatments were assigned codes T0 (control) and T1 through T5, respectively, for simplification. These test concentrations were determined based on range-finding test results. The test substance is of low water solubility; therefore the test solutions were prepared using the WAF procedure (OECD, 2000). Exposure chambers were 250 mL chemically inert clear glass vessels, and contained 100 mL of growth medium. All test exposures consisted of three individual replicates, and six control replicates were evaluated. A surrogate replicate for assessment of water quality conditions was established for each control and test exposure. All replicates utilized an initial cell density of approximately 10,000 cells/mL. WAF test preparations were added directly to each test and surrogate vessel. Test results indicated that eighty-six percent inhibition was observed in the highest test concentration (T5, 60 mg/L WAF), and fifty-six percent growth inhibition was observed in the T4 concentration (30 mg/L initial loading rate WAF). The T3 test concentration (1S mg/L WAF) exhibited slightly more than 50 percent (51.1 percent) growth inhibition. The two lowest test concentrations (T1 and T2) exhibited less than 50 percent growth inhibition. The NOEC (No Observed Effect Concentration) was 3.75 mg/L WAF. Statistically significant effects (alpha 0.05) were observed at the T2, T3, T 4, and T5 exposure concentrations. Based on nominal initial loading rates, an EL50 value of 14.6 mg/L WAF was calculated. The associated 95 percent confidence intervals were 11.7 to 30.0 mg/L WAF.

Adequate reliable measured and estimated data exists for toxicity to algae of constituents of Alchisor TAL 123 (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol). While adequate reliable measured and estimated data exists for toxicity to algae of constituents of Alchisor TAL 123, the most reliable and relevant study result for classification has been identified as the Alchisor TAL 123 study (ENVIRON, 2012), which reports a 72 -hr NOEC based on cell count of 3.75 mg/L WAF. However, while loading rate studies can be used for classification, they cannot be used for PNEC derivation (REACH endpoint guidance, chapter 7b). Therefore, in a protective approach the most sensitive study result from across the three constituents has been identified and used to address the hazard endpoint in question. The most sensitive study result from across the three constituents has been identified as a reliable study with dodecan-1-ol (Huls, 1997) which reports a nominal 72-hr NOEC based on growth of 0.085 mg/L. This value will be taken as the toxicity in aquatic algae endpoint for Alchisor TAL 123.

Concerning the appropriateness of the WAF approach, Alchisor TAL 123 is a complex UVCB and is a mixture of different components (primarily hydrocarbons) exhibiting a variety of physico-chemical properties. When released in the environment, the components in this mixture will behave differently according to their specific properties (e.g. water solubility, vapour pressure, logKow). This behavior will define their environmental fate and toxicity. To address this issue, CONCAWE (the oil producers’ trade organization) developed the Water Accommodated Fraction (WAF) methodology in the early 1990s. In this methodology, different loadings of the substance are added to the test medium and equilibrium between the water and the hydrocarbons is achieved according to their specific water solubility. The hydrocarbon concentrations at equilibrium will be characteristic of the loading of the substance, and therefore toxicity values from WAF studies are expressed as effect loadings or lethal loadings (EL or LL), not as concentrations. The WAF methodology is widely accepted for the testing of complex hydrocarbon substances and other UVCBs, and it has been incorporated in different guidance documents, including the REACH guidance:

• CONCAWE report 92/56 (1992): ecotoxicological testing of petroleum products https://www.concawe.eu/content/default.asp?PageID=569

• OECD Series on Testing and Assessment, no. 27 (2001): Guidance Document on the Use of the Harmonized System for the Classification of Chemicals which are Hazardous for the Aquatic Environment. Paragraph 71.

• International Maritime Organization GESAMP EHS 28 Document (1993) Guidelines for aquatic toxicity testing of mixtures containing compounds of low water solubility.

• REACH endpoint guidance, chapter 7b: considerations for substances with many components, Table 7-8-3, page 71. The REACH guidance specifically states “the acute lethal loading level (typically expressed as the E(L)L50) is comparable to L(E)C50 values determined for pure substances tested within their solubility range. It may therefore be used directly for classification.” http://echa.europa.eu/documents/10162/13632/information_requirements_r7b_en.pdf

• Globally Harmonized System of Classification and Labeling of Chemicals (GHS), fourth revised edition (2011): Annex 9 (Guidance on Hazards to the Aquatic Environment), Difficult to test substances. On page 484, it is stated that “Many substances covered by the classification scheme are in fact mixtures, for which measurement of exposure concentrations is difficult, and in some cases impossible. Substances such as petroleum distillate fractions, polymers, substances with significant levels of impurities, etc can pose special problems since the toxic concentration is difficult to define and impossible to verify. Typical testing procedures often rely on the formation of a Water Soluble Fraction (WSF) or Water Accommodated Fraction (WAF) and data are reported in terms of loading rates. These data may be used in applying the classification criteria.”

• ECHA Guidance on the Application of the CLP Criteria, version 3.0 (2012): Annex I Aquatic Toxicity, section 4.5 on Complex substances. The REACH guidance specifically states that “complex substances are characterized by a range of chemical structures, frequently in a homologous series, but covering a wide range of water solubilities and other physicochemical characteristics. On addition to water, equilibrium will be reached between the dissolved and undissolved fractions which will be characteristic of the loading of the substance. For this reason, such complex substances are usually tested as a WSF or WAF, and the L(E)C50 recorded based on the loading or nominal concentrations. Analytical support data are not normally available since the dissolved fraction will itself be a complex mixture of components. The toxicity parameter is sometimes referred to as LL50, related to the lethal loading level. This loading level from the WSF or WAF may be used directly in the classification criteria.”