Estimation of chemical hazards in breast milk

The presence in the workplace of women who desire to breast feed has complicated the interpretation of what constitutes a safe work environment. There is concern that levels of chemicals found safe for occupational exposure may result in unacceptably high levels of those same chemicals in breast milk. To date, there is no evidence of harm to breast-feeding infants whose mothers are not exposed above a permissible exposure limit (PEL). While we may take some comfort in this, "no evidence of harm" is not the same as "evidence of no harm." Unfortunately, the latter, being a negative, can never be proven. It is with this in mind that this paper is written. We present basic data for a systems approach to determining the hazard presented by a substance in breast milk.