Duration of breast-feeding and PBBs. (Correspondence).Thomas et al. (1) report that polybrominated biphenyl (PBB PBB: see polybrominated biphenyl. ) exposure has no effect on duration of lactation lactation Production of milk by female mammals after giving birth. The milk is discharged by the mammary glands in the breasts. Hormones triggered by delivery of the placenta and by nursing stimulate milk production. . Their data come from interviews in 1997 or later with women who were exposed to PBBs in the mid-1970s and who had a child since then. In a study contemporary with the exposure, however, Weil (2) found that unexposed women breast-fed breast·feed or breast-feed v. breast-fed , breast-feed·ing, breast-feeds v.tr. To feed (a baby) mother's milk from the breast; suckle. v.intr. To breastfeed a baby. about twice as long as exposed women (30 weeks vs. 15 weeks). This might have been because of the warnings about breast-feeding breast-feeding /breast-feed·ing/ (brest´fed?ing) nursing; the feeding of an infant at the mother's breast. with PBB-contaminated milk (3), which we recall as being more ominous than reported by Thomas (1), or because of some biological effect of PBB. In any event, the presence of the finding then and its absence now causes us to speculate that there may be poor recall or other reasons why duration of lactation does not work well as a recalled outcome. Consistent with that speculation, cigarette smoking by the mother (4) and infant's gestional age < 37 weeks (5), for example, are usually associated with early weaning weaning, n the period of transition from breast feeding to eating solid foods. weaning the act of separating the young from the dam that it has been sucking, or receiving a milk diet provided by the dam or from artificial sources. , but the hazard ratios for these characteristics in the report by Thomas et al. (1) are small and nonsignificant non·sig·nif·i·cant adj. 1. Not significant. 2. Having, producing, or being a value obtained from a statistical test that lies within the limits for being of random occurrence. . It is disappointing to think that PBB did interfere with lactation but that the effect cannot be detected in data about lacation recalled years later. Walter J. Rogan National Institute of Environmental Health Sciences Research Triangle Park, North Carolina E-mail: rogan@niehs.nih.gov William B. Weil Michigan State University East Lansing, Michigan REFERENCES AND NOTES (1.) Thomas AR, Marcus M, Zhang RH, Blanck HM, Tolbert PE, Hertzberg V, Henderson AK, Rubin C. Breast-feeding among women exposed to polybrominated biphenyls in Michigan. Environ Health Perspect 109:1133-1137 (2001). (2.) Weil WB, Spencer M, Benjamin D, Seagull seagull a noisy, gregarious bird that frequents the seashore. Web-footed, hook-billed, white with gray wings. Member of the family Laridae and of the genus Larus. E. The effect of polybrominated biphenyl on infants and young children. J Pediatr 98:47-51 (1981). (3.) Finberg. PBBs: the ladies' milk is not for burning. J Pediatr 90:511-512 (1977). (4.) Counsilman J J, MacKay E. Cigarette smoking by pregnant women with particular reference to their past and subsequent breast feeding behavior. Aust N Z J Obstet Gynaecol 101:25-29 (1985). (5.) Bereczkei T. Maternal trade-off in treating high risk children. Evol Hum Behav 22-197-212 (2001). |
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