Breast cancer risk and exposure to organochlorine
insecticides: consideration of the epidemiology data on dieldrin,
DDT and certain hexachlorocyclohexane isomers
COC statement COC/99/S3 - July 1999
Overview of the COC statement
The COC has finalised its evaluation of whether a number of organochlorine
insecticides may cause breast cancer. The Committee evaluated the hypothesis
that organochlorine insecticides might increase the risk of breast cancer
by virtue of their claimed oestrogenic effects. Thus, if a particular
chemical had no oestrogenic activity in vivo, then there was no
rationale as to why it could be considered as a risk factor for breast
cancer. A summary (prepared by the Secretariat) of the main conclusions
is given below. You should read the full statement in order to obtain
detailed information on the Committee's conclusions and how they were
derived.
Secretariat summary of COC conclusions
OC Insecticide
(OCI)
1.Oestrogenic in-vivo?
2. Evidence for persistence in tissues?
(UK data)
3.Convincing epidemiological evidence for
association with breast cancer?
4. Overall conclusion
DDT
(including all isomers / metabolites) e.g. pp'DDE
Yes
(some isomers & metabolites)
Yes
(but levels of pp'DDE declining)
No
(substantial number of studies mainly on pp'DDE available)
Not a cause for concern as a risk factor for human
breast cancer
Dieldrin
No
Yes
(but levels declining)
No
(limited number of studies available)
Not a cause for concern as a risk factor for human
breast cancer
Beta-HCH
(Hexachloro cyclohexane)
Yes
Yes
(some recent evidence that levels are declining)
No
(limited number of studies available)
Published literature on this chemical should be kept
under review
Gamma - HCH
(Lindane)
No
No
No
(limited number of studies available)
Not a cause for concern as a risk factor for human
breast cancer
The Committee agreed that there was no evidence for any synergistic
interaction between organochlorine insecticides in respect of oestrogenic
activity. The Committee noted that there was a considerable amount of epidemiological
research underway, mainly in the U.S.A. and it was agreed that these investigations
should be reviewed when published.
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