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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