In this study, Dr. De-Kun Li and his colleagues assessed prenatal MF exposure by having pregnant mothers wear a gaussmeter for 24 hours. The 733 children were followed for up to 13 years to assess their weight gain. The researchers found a dose-response relationship between prenatal MF exposure and the risk of childhood overweight and obesity. The researchers examined many factors that could explain this association and controlled for them statistically. The children with the highest prenatal MF exposure were similar to other children in most regards.
Since the researchers did not assess the children’s behaviors or exposures after they were born, it is possible that such factors could be confounded with the observed association between prenatal MF exposure and obesity. For example, if children’s postnatal MF exposures were highly correlated with their prenatal MF exposures, then their postnatal exposures to MF may have contributed to the observed weight gain in this study.
A year ago, Dr. Li reported increased risk of childhood asthma among children in this study who had the highest MF exposure prenatally. Earlier research conducted by Dr. Li found evidence of sperm damage in adult males and higher miscarriage rates in adult females who had been exposed to higher levels of MF.
This research needs to be replicated. Subsequent studies should monitor relevant postnatal behaviors of the children as well as exposure to electromagnetic radiation including mobile phone use in addition to assessing weight gain and chronic disease incidence.
Given the widespread and increasing use of wireless technologies, health effects research is needed on mobile phones, wi-fi, and smart meters as well as household appliances and power lines. Research is also needed on the expanding group of individuals who experience functional impairments associated with “electrosensitivity.”
Prospective research studies require considerable time, patience, and funding. The Federal government needs to underwrite a major research initiative on the health effects of electromagnetic radiation independent of industry to prevent conflicts of interest.
In the interim, prospective parents and children should take precaution and reduce their exposure to electromagnetic fields. Since the researchers in the current study did not assess the sources of MF exposure, we have compiled a list of various sources of MF exposure from common household appliances (see Appendix).
Joel M. Moskowitz, Ph.D.
For more information, see:
1. “In-Utero Exposure to Magnetic Fields Associated with Increased Risk of Obesity in Childhood.” Kaiser Permanente, PR Newswire, July 27, 2012; http://www.marketwatch.com/
2. “EMF Exposures in the Womb Can Lead to Childhood Obesity.” Microwave News, July 27, 2012. http://microwavenews.com/
3. Li DK, Ferber JR, Odouli R, Quesenberry Jr CP. A Prospective Study of In-utero Exposure to Magnetic Fields and the Risk of Childhood Obesity. Scientific Reports. 2(540):1-6. Published 27 July 2012. http://www.nature.com/
4. Li DK, Chen H, Odouli R. Maternal exposure to magnetic fields during pregnancy in relation to the risk of asthma in offspring. Archives of Pediatrics & Adolescent Medicine. 2011;165(10):
We conducted a prospective study to examine whether in-utero exposure to magnetic fields (MFs) increases the risk of childhood obesity. Participating women carried a meter measuring MF levels during pregnancy and 733 of their children were followed up to 13 years to collect clinically recorded information on growth patterns with 33 weight measurements per child on average. Prenatal exposure to high MF level was associated with increased risk of being obese in offspring than those with lower MF level (odds ratio = 1.69, 95% confidence interval: 1.01–2.84)
Magnetic Fields (in milligauss) Emitted by Household Appliances at Typical Operating Distances
Toaster, coffee maker, electric oven, dishwasher, refrigerator (at 3 feet): less than 1
Computer, television (at 3 feet): less than 1
Washing machine (at 3 feet): less than 2
Fluorescent light fixture (at 3 feet): less than 3
Cell phone (at the head): 1.2-2
Iron (at 1 foot): 1-3
Electric range, electric can opener (at 3 feet): 4
Microwave oven (at 3 feet): 3-6
Power lines (at 100 feet): 0.5-12
Vacuum cleaner (at 1 foot): 1-20
Alarm clock (at 4 inches): 5-15
Fluorescent desk lamp (at 1 foot): 6-20
Electric blanket (at 1 inch): 3-50
Iron (at 4 inches): 12-45
Electric range (at 1 foot): 22
Electric mixer (at 1 foot): 53
Microwave oven: (at 1 foot): 40-80
Computer (at 1 inch): 5-300
Hair Dryer (at 1 inch): 60-20,000
Electric shaver (at 1 inch): 150-15,000