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EC number: 202-049-5
CAS number: 91-20-3
In various small-scale batch experiments using natural sources of water and sediment under aerobic and anaerobic conditions, biodegradation of naphthalene occurred efficiently under strictly aerobic conditions, leading to turnover times of 13 hours in the sediment compartment and 310 hours (13 days) in the water compartment and to complete degradation within 21 days. Furthermore, in one experiment the dependence of the naphthalene degradation on the contamination degree of the water/sediment system has been clearly demonstrated, providing evidence of the acclimatisation ability of the microbial system. It can be concluded that naphthalene is readily biodegradable in the water/sediment compartments under aerobic conditions.
No useful long-term degradation half-lives
or environmental kinetic elimination constants have been located. In
none of the four reports which were taken into account, values for
half-lives have been determined. By weight of evidence, it can be
concluded that naphthalene is easily/inherently degradable without signs
of bioaccumulation. The limiting factor is anoxic/anaerobic conditions
such as they may prevail in sediment.
Given this fact, it was proposed to use
default half-lives of 150 days in surface water and 3000 days in
sediment for risk assessment (UK 2007):
These global allocations to temporal
categories for aromatic substances
were first adopted in the Risk Assessment report for risk assessment of
CTPHT (Coal-tar pitch, high temperature) (ECB 2008, pp. 66/67),
taken from Mackay et al. 1992: "On the basis of model
calculations, Mackay et al. (1992) ranked the 16 EPA PAH according to
their persistence in water, soil and sediment in different classes which
correspond to a specific half-life in these compartments..."
This not well-founded conclusion should not
be taken for granted for a potentially easily degradable substance like
naphthalene, even though evaluable long-term elimination data are
UK 2007: Environment
Addendum of December 2007 to the EU Risk Assessment of naphthalene,
final approved version. UK Environment Agency, Chemicals Assessment Unit
ECB 2008: European
Union Risk Assessment Report: Coal-tar pitch, high temperature. Draft
environmental risk assessment report, Rapporteur: The Netherlands.
European Chemicals Bureau. [R323_0805_ENV_FINAL_ECB.DOC]
Mackay D, Shiu WY, and Ma KC 1992: Illustrated
Handbook of Physical–Chemical Properties and Environmental Fate of
Organic Chemicals. Lewis Publishers, Boca Raton, FL.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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