Council on Environmental Health
Prepared by: Sharon A. Savage, MD
Prenatal and Postnatal Exposure to Cell Phone Use and Behavioral Problems in Children
Hozefa A. Divan, Leeka Kheifets, Carsten Obel, and Jorn Olsen
Epidemiology, July 2008, 19(4): 523-529
Technological advances in telecommunications have led to concerns about levels of exposures to non-ionizing radiation in the form of radiofrequency fields (RF). Individuals are exposed to RF during cellular telephone use.
The effect of RF on the developing nervous system of a child is not known. The authors’ hypothesized that exposures early in life may have particular importance because they occur at vulnerable stages of brain development. There are no established causal mechanisms known for RF effects on health, except for those potentially caused by an increased temperature in the exposed region. The authors suggest that this makes it impossible to exclude any health outcomes from consideration.
This study was based on the Danish National Birth Cohort which recruited subjects between 1996 and 2002. A total of 101,032 pregnancies were enrolled. The mothers and live-born children will be followed for decades as two cohorts. This analysis was based on information collected about children born between 1997 and 1999.
A questionnaire was administered when children reached 7 years of age which included questions on social conditions, behavioral problems, and cell phone use by children and the mothers during pregnancy. The Strengths and Difficulties Questionnaire assessed behavioral problems based on responses from a list of 25 questions. Based on the responses, children were classified as abnormal, borderline, or normal for overall behavioral problems as well as emotional, conduct, hyperactivity, or peer problems. Comparisons of cell phone use and exposure were made and dose-response patterns were estimated.
- Mothers of 13,159 children completed the questionnaires.
- Greater odds ratios for behavioral problems were observed for children who had possible prenatal or postnatal exposure to cell phone use.
- The odds ratio for higher overall behavioral problems for children with both prenatal and postnatal exposure to cell phones was 1.80 (95% confidence interval 1.45-2.23) after adjustment for possible confounders (sex of child, age of mother, smoking during pregnancy, mother’s psychiatric problems, and socio-economic levels).
These results were unexpected and the authors urged caution in the interpretation of their study. The observed associations are not necessarily causal as there is no known biological mechanism to explain these associations. They were unable to precisely measure the RF levels of exposure and had to rely on questionnaire data which precludes the determination of precise measurements.
The associations may be noncausal and may be due to unmeasured confounding. However, the immature nervous system is vulnerable to toxicants and it is possible that behavior-related toxicities will not emerge until well into childhood, adolescence or adulthood. They will continue to follow this cohort of children.
This was the first large, prospective cohort study to evaluate cell phone exposure and childhood behavior problems. The associations between behavior problems and cell phone use are intriguing but need to be interpreted very cautiously because there is no known biological basis for the findings. This is the first study of its kind and future studies must be conducted.