Environmental exposure and cancer in children. A conceptual framework for the pediatrician

Ultimately, after gathering and assessing all available evidence, pediatricians and health care policymakers must make informed decisions on whether exposure to a specific agent has the potential to cause cancer in children. In the case of DES, for which the results were clear, there was no question that the drug should be taken off the market; however, most cases of suspected carcinogens lack such clear evidence documenting cause and effect. An example of a murky topic is the suspected relationship between residential electromagnetic fields (EMFs) and childhood cancer. Epidemiologic and biologic researchers have tried for more than 2 decades to determine whether exposure to relatively high levels of EMFs poses health hazards, especially cancer in children. Although the preponderance of evidence favors a judgment that this ubiquitous environmental exposure is harmless, concerns remain in many public circles and some scientific ones. Any proposed intervention to remove a potentially carcinogenic agent must be weighed against the cost and inconvenience to the affected community. Pediatricians are placed in a vulnerable position when faced with questions of a carcinogenic potential because of the frequency of claims in the popular literature stating that exposure to a certain product or food is associated with an increased risk for cancer in adults and possibly children. When such studies are published or, more often, released to the press, the strength of the evidence for a causal association with cancer, coupled with the context of the study, should be considered as a reasonable starting point. Better communication models of disseminating cancer-risk information are needed so that the public understands the difference between a weak study that appeared on the local news with little evidence to support a cause-and-effect relationship versus a well-designed study that was published in a peer-reviewed journal and indicates a likely cause-and-effect association.