Hexachlorobenzene in human milk: a polyhalogenated risk

Hexachlorobenzene (HCB) produces a spectrum of biological and toxic conditions that are characteristic of polyhalogenated aromatic compounds. In humans, HCB is easily absorbed through the lymphatic system to accumulate in fat tissues, and persists for many years since it is highly lipophilic and resistant to metabolic conditions. With a view to assessing the HCB risk to humans, human exposure was measured in milk fat. A hundred individual milk samples were collected, 99 of which contained HCB. The mean HCB concentration on a fat basis was 0.08 ppm (range 0.01-0.70 ppm). Most samples contained less than 0.1 ppm HCB, 11% contained 0.1-0.2 ppm and two samples greater than 0.2 ppm. The results obtained were compared with surveys carried out in other countries, and were correlated with levels of polychlorinated biphenyls because these compounds resemble HCB in their source of contamination, absorption, metabolism, fat affinity and toxicological spectrum. There is a need to develop comparative approaches which consider the effects of a single compound against the whole spectrum of likely contaminants, to take account of the possibility of joint action leading to additive or synergistic effects. Further studies are needed on the toxicological effects of polyhalogenated compounds in human milk, since these compounds will be present in the body for many decades and reach infants at an early stage through placental transfer and breast-feeding.