Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 202-049-5
CAS number: 91-20-3
The results regarding the
biodegradation of naphthalene are quite conflicting: The biodegradation
rate (2 % degradation after 4 weeks) - obtained in a standard screening
test for inherent biodegradability (MITI II) (NITE 1979) - led to
the assumption that naphthalene is not inherently biodegradable. This is
in contrast to a finding under conditions of ready biodegradability,
which provided evidence that naphthalene is readily biodegradable (Yoshida
et al. 1983). Furthermore, various biodegradation results obtained
in tests under non-standardised conditions led to the conclusion that
naphthalene is easily biodegradable. In this context, it has to be taken
into account that the rapid biodegradation occurred under aerobic and
denitrifying conditions. Easy biodegradation has also been observed in
systems in which microorganisms were acclimatised to the pollution by
PAHs in general and by naphthalene in particular. Under the
aforementioned conditions, naphthalene was degraded to less than
measurable levels in numerous cases within a period of 5 –
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, but
also adsorption to organic matter. In ECB 2008 (p. 65), the
rapporteur decided as follows: "Obviously, due to the large variations
it is difficult to predict half-lives of PAHs. For the risk assessment,
it is decided to use the suggested mean half-lives by Mackay et al.
This procedure ended in the conclusion (see UK
2007) that naphthalene is to be considered persistent, since the
default half-lives calculated by Mackay et al. (1992) for sediment
apparently are supportive of this view.
Even though evaluable long-term elimination
data are lacking, this conclusion seems to be unjustified in light of
the fact that naphthalene is a potentially easily degradable substance,
in general showing short residence time in natural environment (rapid
biodegradation). Note: At that time (before 2007), the Japanese study
revealing ready biodegradability of naphthalene (Yoshida et al. 1983)
was not taken into account, because it was probably unknown. Else, the
judgment may have been different.
UK 2007: Environment
Addendum of December 2007 to the EU Risk Assessment of naphthalene,
final approved version. UK Environment Agency, Chemicals Assessment Unit
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.
Welcome to the ECHA website. This site is not fully supported in Internet Explorer 7 (and earlier versions). Please upgrade your Internet Explorer to a newer version.
Do not show this message again