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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
experimental study planned
Justification for type of information:
TESTING PROPOSAL ON VERTEBRATE ANIMALS

NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on (and for) which testing is proposed to be carried out : Amides, C16-18 (even numbered), N-C16-18 (even numbered) alkyl


CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION [please address all points below]:
- Available GLP studies : OECD 210, OECD 211
- Available non-GLP studies : none
- Historical human/control data : none
- (Q)SAR : substance not in the applicability domain regarding most of the models available :
BCFBAF v3.01 (EPISUITE*), Meylan, KNN/Read-Across, Arnot-Gobas (BCF model VEGA*), OPERA Models.
*Note that due to complex composition of the test item (UVCB), the worst case constituant (C36, C36H73NO,535.99 g.mol-1) was assessed.
- In vitro methods :none
- Weight of evidence : not applicable
- Grouping and read-across : none


CONSIDERATIONS THAT THE SPECIFIC ADAPTATION POSSIBILITIES OF ANNEXES VI TO X (AND COLUMN 2 THEREOF) OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- According REACH Annex IX column 2, the bioaccumulation study not need to be performed if the substance has a low potential for bioaccumulation (for instance a log Kow = 3) and/or a low potential to cross biological membranes. The registered substance has a log Kow > 6,5 according an experimental study following TG OECD 117 and has a quite low molecular weight for each of these constituant (479 - 537 g.mol-1) therefore it is not possible to waive the bioaccumulation study.

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Chapter R.7b (version 4.0, June 2017), Section R,7,8.5 defined that a substance is poorly water soluble when water solubility below 1 mg/L or below the detection limit of the analytical method of the test substance. It has a low water solubility < 0,053 mg/L at 20°C according to an experimental study following TG OECD 105 therefore the bioavailability of the substance in water is negligible.
- The registered substance has also has a high partition coefficient (log Kow of > 6,5 according TG OECD 117) indicating a potential to bioaccumulate and has a strong adsorption Log Koc >= 5.63 (20°C) according an experimental study following TG OECD 121 and GLP (HPLC method). Moreover, biotic degradation studies in water indicate that the substance is not readily biodegradable and has a DT50 = 2,6 - 10,6 days at 12 °C in water according TG OECD 301B and 308. Stable concentrations in water will be impossible to demonstrate, confirmed by the low recoveries observed all along the long term aquatic studies OECD 210 and 211 (Old WAF : < LOQ to 0.02 mg/L). Considering all these difficulties, the dietary route would be more appropriate for bioaccumulation testing (305-III).

Qualifier:
according to guideline
Guideline:
OECD Guideline 305 (Bioaccumulation in Fish: Aqueous and Dietary Exposure) -III: Dietary Exposure Bioaccumulation Fish Test
Version / remarks:
October 2012
GLP compliance:
yes (incl. QA statement)

Description of key information

No experimental study on bioaccumulation is available on the registered substance. Considering that the applicability domain of the QSAR is not fulfilled, a bioacumulation test on fish is proposed according the TG OECD 305.


In a supporting study, the BCF has been predicted to be 381.4 L/kg wet-wt calculated on the worst case constituent (C36 H73 N1 O1 having the highest lipophilic potential log Kow, predicted among the UBVC's constituents). Considering the registered substance properties the experimental log kow is higher than > 6,5 according to TG OECD 117 and the predicted log Kow is = 15,5 according to KOWWIN v1.68. Therefore, the registered substance falls outside the applicability of the BAFBCF model based on the log Kow descriptor. The result of the estimation if therefore considered not to be completely reliable.

Key value for chemical safety assessment

BCF (aquatic species):
381.4 L/kg ww

Additional information

According REACH Annex IX column 2, the Bioaccumulation not need to be performed if the substance  has a low potential for bioaccumulation (for instance a log Kow ≤ 3) and/or a low potential to cross biological membranes. Considering the properties of the registered substance, it is not possible to waive the bioaccumulation study.


Chapter R.7b (version 4.0, June 2017), Section R,7,8.5  defined that a substance is poorly water soluble when water solubility below 1 mg/L or below the detection limit of the analytical method of the test substance. The registered substance has a low water solubility < 0,053 mg/L at 20°C  according to an experimental study following TG OECD 105 therefore the bioavailability of the substance in water is negligible.


The substance has also a high partition coefficient (log Kow of > 6,5 according TG OECD 117) indicating a potential to bioaccumulate and has a strong adsorption Log Koc >= 5.63 (20°C) according an experimental study following TG OECD 121 (HPLC method). Moreover, biotic degradation studies in water indicate that the substance is not readily biodegradable and has a DT50 = 2,6 - 10,6 days at 12 °C in water according TG OECD 301B and 308. Stable concentrations in water will be impossible to demonstrate, confirmed by the low recoveries observed in the long term aquatic studies OECD 210 and 211 (Old WAF : < LOQ to 0.02 mg/L). Considering all these difficulties, a bioaccumulation test in fish is proposed according TG OECD 305, the dietary route would be more appropriate for testing (305-III).