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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Toxicity

AHTN is Not T based on:

  • The lowest NOEC for aquatic organisms is 0.022 mg/l which does not meet the T-criterion of 0.01 mg/L. All toxicological tests performed on mammals only justify the classification Harmful when/if swallowed (R22 or H302), so AHTN does not meet any of the classifications mentioned for the T-criterion.

Bioaccumulation

AHTN is Not B or vB based on:

  • Bioaccumulation factors determined in fish. The BCF in laboratory studies is circa 600; AHTN is readily metabilised and excreted; its transformation products are water soluble and have a low log Kow.
  • The low BCF is confirmed by BCFs derived from field studies.
  • Field studies did not show any indications for biomagnification of AHTN in the food chain.

Persistence

AHTN is Not P or vP based on:

  • Although AHTN does not rapidly mineralize, the parent material steadily disappeared from river water with an overall half-life of circa 9 days. The loss due to biodegradation was 42% after 28 days. Biotransformation products are water soluble with log Kow < 4 (so they do not meet the 'B'-criterion. Other studies confirm the biodegradability of the substance.
  • With 42% primary biodegradation in a CAS test, AHTN is classified as 'inherently biodegradable'.
  • The environmental concentrations reflect the decreasing use volume of the substance, illustrating the AHTN is degraded in the STP/aquatic environment.
  • AHTN in sludge applied to soils disappeared fast.
  • Volatilisation may be a relevant pathway but in view of the rapid degradation under atmospheric conditions, AHTN has a short-lifetime in this compartment.

It is concluded that AHTN is not P.

Since AHTN is not T, not B or vB and not P, AHTN is not a PBT/vPvB substance.