Exposure Now, Sickness Later.

Early Exposure to PCBs and Dioxins May Increase Some Childhood Diseases

It is nearly impossible to totally avoid contact with polychlorinated biphenyls (PCBs) and dioxins, ubiquitous pollutants that are produced by the electrical, plastics, pesticide, paper, and other industries. These fat-soluble toxicants accumulate in the food chain, especially in meat, fish, and dairy products. Mothers pass PCBs and dioxins to their children through the umbilical cord and breast milk.

A team now headed by pediatrician Nynke Weisglas-Kuperus of Erasmus University and Sophia Children's Hospital in Rotterdam, The Netherlands, explores the longer-term immunological consequences of PCB and dioxin exposure in older children [EHP 108:1203-1207]. Using data gathered under the leadership of Pieter J. J. Sauer, now chairman of pediatrics at the University of Groningen, they report for the first time that perinatal exposure to PCBs and dioxins affects the occurrence of infectious diseases and allergic disorders in preschool-age children.

The current study is part of the Dutch PCB/Dioxin Study, a longitudinal neurodevelopmental study aimed at investigating the adverse effects of background exposure to PCBs and dioxins in the growth and development of healthy full-term infants. Pregnant women were recruited by midwives in Rotterdam and the surrounding area between 1990 and 1992. The women did not know whether they were exposed to high or low amounts of PCBs and dioxins.

For 207 healthy newborn infants, perinatal exposure to the pollutants was estimated by measuring PCBs in their mothers' blood and umbilical cord blood, and by measuring PCBs and dioxins in their mothers' breast milk. About half of the infants were breast-fed; the rest drank formula from a single lot with no detectable concentrations of PCBs or dioxins.

Blood samples were taken from the children at 42 months of age. By 42 months, breast-fed children showed 3-4 times the concentration of toxicants in their blood than formula-fed children. Also at this point, each mother completed a questionnaire about her child's health status, including episodes of infectious and allergic diseases throughout the preschool years. Concentrations of circulating antibodies for mumps, measles, and rubella were also measured in the children's blood samples. All but one child had received vaccinations for these childhood illnesses at 14 months.

Among all the children, infectious diseases had occurred more often than allergic ones. For instance, 103 children (59%) suffered middle-ear infections, and 130 (74%) contracted chickenpox. In contrast, only 14 (8%) reported allergic reactions, and 17 (10%) reported attacks of shortness of breath. Perinatal exposure to PCBs and dioxins correlated with slightly lowered concentrations of antibodies for mumps and rubella. In a subgroup of 85 children, other immunologic properties were assessed, including numbers of B cells, T cells, monocytes, granulocytes, and lymphocytes. Perinatal exposure to PCBs and dioxins increased the numbers of memory, cytotoxic, and activated T cells. Together, these immune tests suggest that perinatal exposure may increase susceptibility to infectious diseases at preschool age.

The researchers found that the higher the child's body concentration of PCBs and dioxins at age 42 months, the higher the likelihood of having developed recurrent ear infections or chickenpox. However, the prevalence of allergic diseases fell as the exposure to PCBs and dioxins rose. Although other researchers have observed similar connections, such as the presence of tuberculosis correlating with an absence of asthma among school children, the effect is not yet well understood.

The researchers do not discourage breast-feeding; instead, they suggest finding ways to reduce consumption of the toxicants in foods so that less is transferred perinatally to children. The researchers also conclude that future studies should monitor children later in childhood and adulthood to assess the lifetime impact of PCBs and dioxins on the immune system.