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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Predicted log BCF of 0.5 = 3.2 L/kg wet weight

Key value for chemical safety assessment

Additional information

The bioaccumulation in aquatic species study required in REACH guidance, Annex IX (Section 9.3.2) does not need to be conducted as the substance and its hydrolysis products have low potential for bioaccumulation with a partition coefficient of less than zero (log Kow < 0).

However, an estimated BCF of 3.2 (log BCF = 0.5) was obtained for citric acid using BCFBAF program which forms part of the Syracuse EPIWEB suite. The estimated value of citric acid is well below the cut off value of BCF ≥ 500 that is considered to indicate potential for bioaccumulation; the result indicates that citric acid is not expected to bioaccumulate.

Citrate is found in all eukaryotic cells as an intermediate of the TCA cycle, which is part of the basic metabolic pathway that generates useable energy from carbohydrates, proteins and fats. Citric acid is formed and broken down in the course of this cycle at very high rates.The weight of evidence of the low estimated BCF, biodegradability and role in cell metabolism indicate that citric acid is extremely unlikely to bioaccumulate and testing is not considered necessary for this endpoint.

The accumulation of zinc which is an essential element is regulated in animals of several fish, crustaceans and mammals. In mammals, one of the two target species for seconsdary poisoning, both the absorption of zinc from diet and zinc excretion are regulated. The process allows mammals with certain limits to maintain the level of zinc in their body (whole body homeostasis) and to maintain physiologically required levels of zinc in their tissues both at low and high zinc dietary intake. In a field study, relatively small difference was found in the zinc levels of small mammals from control and polluted site. This observation was due to the homeostatic mechanism. Therefore, the bioaccumulation potential of zinc is expected to be low.

The effect of trizinc dicitrate when in solution is not expected to differ significantly from the effects of the citrate anion(H7C6O7-)and the metal ion separately, so exposure will be to citric acid and the metal ions separately.