Obesity and asthma

Obesity and asthma

Neurologic and cardiovascular effects of methylmercury There is general concern about childhood exposure to environmental toxins. There is considerabl...

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Neurologic and cardiovascular effects of methylmercury There is general concern about childhood exposure to environmental toxins. There is considerable concern about lead exposure, based on decades of research. Considerably less is known regarding other exposures. Organic mercury may be an important exposure. This is in part due to the fact that methylmercury is present in many varieties of fish. In this issue of The Journal, Grandjean et al and Murata et al report on the effects of methylmercury exposure after 14 years of follow-up in a cohort of children from the Faroe Islands. They report that intrauterine exposure to higher levels of methylmercury may lead to irreversible neurotoxic effects as well as decreased sympathetic and parasympathetic modulation of heart rate variability. They suggest that further study is needed of postnatal methylmercury exposure during childhood in addition to prenatal exposure. In these studies, it was difficult to separate the pre- and postnatal exposures. Nevertheless, these results add concern for the level of exposure to methylmercury by pregnant mothers and their children. —Stephen R. Daniels, MD, PhD Page 169 (Grandjean et al) Page 177 (Murata et al)

Who grows out of cow’s milk allergy? Many young children with allergy to cow’s milk eventually outgrow their symptoms. Vanto et al have studied predictors of which children will develop tolerance to cow’s milk. In their article, they report that infants with delayed clinical reactions to cow’s milk, those with prick tests <5 mm wheal size, and those with milk-specific IgE levels <2 kU/L have the highest probability of developing tolerance by age 4 years. —Robert W. Wilmott, MD Page 218


February 2004

Obesity and asthma In recent years, the prevalence of both asthma and obesity have increased in North America, and we are currently in the midst of an epidemic of childhood obesity. In adults, there is a positive relationship between asthma and obesity, but whether there is an association in children has been unclear. This question has now been studied in a large populationbased sample of Canadian children age 4 to 11 years. In this issue of The Journal, To et al report an overall prevalence of asthma of 9.9% in 11,199 in children. There was no significant statistical association between obesity and asthma in this population. The greatest single risk factor for asthma was a maternal history of asthma with an odds ratio of 3.69. The authors discuss the possible reasons for the differences between studies and whether there is a true relationship between obesity and asthma in children. This issue is addressed in the accompanying editorial by Dr Yue Chen. —Robert W. Wilmott, MD Page 146 (editorial) Page 162 (article)

‘‘Bone up’’ on bone density There is an appropriate growth in interest in bone mineralization in children with chronic disease. Unfortunately, technology may not be keeping up with this interest. In the current issue of The Journal, Gafni and Baron at the National Institutes of Health, report on 34 children referred to their center for participation in a study of children with osteoporosis. These workers looked at the referral information accompanying the children. Typically, the children had determination of bone mineral density (BMD) in local facilities that were mainly focused on studies of adults. Consequently, the BMD determinations frequently suffered from major flaws, such as failure to use age-, sex-, or ethnicmatched databases for comparison. The net result of this was that more than half of these children, referred for osteoporosis, had normal BMD. Physicians ordering BMD in children may wish to review this study with the centers or facilities they typically use for such measurements. —Thomas R. Welch, MD Page 253

The Journal of Pediatrics