Factors affecting the transfer of organochlorine pesticide residues to breastmilk

Existing studies monitoring organochlorine pesticide residues in breastmilk were examined to identify whether common factors determine the extent of transfer of these residues. A structured review of the English language literature was conducted. Papers were reviewed and assessed using a structured protocol. A total of 77 papers were initially identified, 46 of which contained conclusions relating to the factors which may affect the transfer of residues into breastmilk. Owing to the diversity of findings, papers were screened further to include only those in which a minimum of background information relating to selection of mothers and to milk sampling procedures were reported. Only eight papers were deemed to contain adequate information. Age, parity/length of previous lactation, fat mobilisation and the time of sampling were identified as the most likely factors to be considered when assessing transfer of organochlorine pesticide residues into breastmilk. This review highlights the difficulties of assessing trends in breastmilk contaminants where comparable sampling procedures are not used.