Diisodecyl sebacate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

10 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

1 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.2 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

no exposure of sediment expected

Sediment (marine water)

Hazard assessment conclusion:

no exposure of sediment expected

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no exposure of soil expected

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNEC aqua (freshwater)

No aquatic toxicity test data are available for DIDS. However, reliable short-term toxicity tests are available on DEHS in fish, invertebrates and algae, covering three trophic levels (predators, plant-eating animals, and primary producers, respectively). In good quality guideline studies, NOECs in freshwater fish (Anon, 1994a), Daphnia (Anon, 1994b), and algae (Anon, 1994c) were all 1000 mg/L [the highest tested concentration level]. As these studies show, DEHS does not exhibit acute aquatic toxicity, even at high nominal concentrations. It was noted that analytical test concentrations of DEHS were very low [specific concentrations were not given], probably due to low water solubility. Furthermore, DIDS is readily biodegradable and is unlikely to pose a long-term toxicity risk to freshwater organisms. According to the REACh guidance on information requirements and chemical safety assessment (IR&CSA, Chapter R.10), an assessment factor (AF) of 1000 should be applied when at least one short-term LC₅₀^/EC₅₀ from each of three trophic levels (fish, invertebrates (preferred Daphnia) and algae) is available (ECHA, 2008a). The use of such an AF in this instance is very conservative. As the point-of-departure is not a LC₅₀ or EC₅₀, but rather NOECs for mortality (for fish), mobility (for Daphnia) and growth inhibition (for algae), it is considered that an AF of 100 would provide sufficient conservatism to compensate for the fact that the studies were conducted on a closely-related read-across substance, and not DIDS itself.

PNECaqua (freshwater) = 1000 mg/L / 100 = 10 mg/L

PNEC aqua (marine water)

No toxicity studies were available on saltwater organisms for DIDS (or DIDA, DOS or DEHS). The PNEC aqua (marine water) is therefore based on the freshwater LC₅₀ and EC₅₀ values of more than 1000 mg/L [the highest tested concentration level], as discussed above (Anon, 1994a,b,c). According to chapter R.10 of the IR&CSA, an AF of 10,000 should be applied to the lowest short-term LC₅₀ from freshwater or saltwater representatives of three taxonomic groups (algae, crustaceans and fish) of three trophic levels (ECHA, 2008a). The use of such an AF in this instance is very conservative. As the point-of-departure is not a LC₅₀ or EC₅₀, but rather NOECs for mortality, mobility and growth inhibition, it is considered that an AF of 1000 would provide sufficient conservatism to compensate for the fact that these studies were conducted on a closely-related read-across substance, and not DIDS itself.

PNECaqua (marine water) = 1000 mg/L / 1000 = 1 mg/L

 

PNEC aqua (intermittent releases)

A PNEC for intermittent releases was not calculated. According to chapter R.10 of the IR&CSA, these are required in cases where discharges, and therefore environmental exposure, are limited in time (ECHA, 2008a). This is not the case for DIDS – any environmental exposure (if it did occur) is assumed to be constant. Moreover, the PNEC aqua will be protective of intermittent releases.

PNEC STP (sewage treatment plant)

No standard toxicity data with activated sludge are currently available (or required). However, microbial toxicity is unlikely to occur as DIDS is highly insoluble in water and readily biodegradable. Indeed, in a guideline ready biodegradability test (to GLP) with DIDS, inhibition of the endogenous respiration of the inoculum (river water) by the test substance at day 7 was not detected at a test concentration of 2 mg/L (study NOEC). Chapter R.10 of the IR&CSA suggests that an AF of 10 can be applied to the NOEC from a reliable ready biodegradability test (ECHA, 2008a).

 

PNECmicroorganisms = 2 mg/L / 10 = 0.2 mg/L

PNEC sediment (freshwater) and PNEC sediment (marine water)

PNECs were not calculated for freshwater or marine sediment as exposure to these compartments is not anticipated.

 

 

PNEC air

No data were available on the possible effect of DIDS on the atmosphere. A vapour pressure of <0.00000405 Pa was predicted for DIDS. According to chapter R.7a of the IR&CSA, substances with vapour pressures below 0.01 Pa are “low volatility substances” (ECHA, 2012b). As such, biotic and abiotic effects (e.g. global warming, ozone depletion, acidification) are not expected.

PNEC soil

A PNEC was not calculated for soil as exposure to this compartment is not anticipated. According to chapter R.7c of the IR&CSA, “when soil exposure is considered negligible … neither a PEC, nor PNEC can or need to be calculated” (ECHA, 2012a).

 

PNEC oral (secondary poisoning)

A PNEC oral for secondary poisoning was not calculated. According to chapter R.8 of the IR&CSA, an assessment does not need to be conducted unless the substance has a log Kow of at least 3 or a BCF of at least 100, and there are no mitigating properties such as ready biodegradability or hydrolysis (with a half-life of less than 12 hr) (ECHA, 2011). Being readily biodegradable (and having a BCF <50), DIDS does not fulfil these criteria.

References

ECHA (2008a). Guidance on information requirements and chemical safety assessment. Chapter R.10: Characterisation of dose [concentration]-response for environment. May 2008. Owner company: European Chemicals Agency.http://echa.europa.eu/documents/10162/13632/information_requirements_r10_en.pdf

 

ECHA (2011). Guidance on information requirements and chemical safety assessment. Part B: Hazard assessment. Version 2.1. December 2011.Report no.: ECHA-11-G-16-EN. Owner company: European Chemicals Agency.http://echa.europa.eu/documents/10162/13643/information_requirements_part_b_en.pdf

 

ECHA (2012a). European Chemicals Agency. Guidance on information requirements and chemical safety assessment. Chapter R.7a: Endpoint specific guidance. Version 2.0. November 2012.http://echa.europa.eu/documents/10162/13632/information_requirements_r7a_en.pdf

 

ECHA (2012b). European Chemicals Agency. Guidance on information requirements and chemical safety assessment. Chapter R.7c: Endpoint specific guidance. Version 1.1. November 2012.

http://echa.europa.eu/documents/10162/13632/information_requirements_r7c_en.pdf

Conclusion on classification

In accordance with Regulation (EC) No. 1272/2008 (CLP), a substance should be classified as an acute aquatic hazard if the 96-hr LC₅₀ for fish, the 72- or 96-hr EC₅₀ for algae, or the 48-hr EC₅₀ for crustaceans is 1 mg/L or less. The acute toxicity (LC₅₀/EC₅₀) of DIDS to aquatic species is predicted to be well above 1 mg/L for all trophic levels based on results for DEHS (Anon, 1994a,b,c). Therefore DIDS does not require classification as an acute aquatic hazard under CLP (or DSD).

Under CLP, substances should be classified as chronic aquatic hazards if any of the above criteria for acute aquatic hazard are fulfilled, and the substance is not rapidly degradable and/or the experimentally determined BCF is at least 500 (or, if the BCF is not available, the Log Kow is at least 4). DIDS is readily biodegradable and has a predicted BCF < 50. As such, it does not meet the criteria for classification as a chronic aquatic hazard under CLP (or DSD).