Pregnant women using daily household electrical items could be at increased risk of their children developing asthma.
A study led by Dr. De-Kun Li, a reproductive and perinatal epidemiologist at the Kaiser Permanente in Oakland, California USA, claims that children of pregnant women who have been exposed to magnetic energy emnating from electrical items such as hair dryers, microwaves and vacuum cleaners have a greater risk of developing asthma.
AdvertisementThe study has been published in the online Journal - Archives of Pediatrics & Adolescent Medicine. It is the first to link maternal exposure to magnetic energy and asthma in children.
Previous Studies - There have been earlier studies that have linked exposure to magnetic energy (generated by common sources such as power lines and electrical appliances) to miscarriage, poor semen quality, immune disorders and cancer.
Various other studies pointed fingers at microwaves ovens, hair dryers and vacuum cleaners. However, these studies lacked consistency, as they required to be carried out over a long period of time.
For the recent prospective study, De-Kun Li and his group of researchers examined the daily magnetic field exposure of 801 pregnant women who resided in Northern California.
The scientists then analyzed the medical records (for 13 years) of the children born to these women, to check for asthma.
During their pregnancy the subjects wore on their person a small monitor for 24 hours to record their magnetic field exposure from daily household items such as microwaves, fans, coffee grinders, hair dryers, vacuum cleaners, and fluorescent light bulbs, transformer stations and power lines.
"In this study we observed a dose-response relationship between mother's MF (Magnetic Field) level in pregnancy and the asthma risk in her offspring.In other words, a higher maternal MF exposure during pregnancy led to a higher risk in offspring." Dr De-Kun Li said.
According to Li, for the average population, children of women whose level of exposure was in the range of the bottom 10 percent would have approx. 13.6 percent absolute risk of developing asthma while women whose exposure was in the highest range carry a 33 percent risk of producing children who developed asthma during the 13-year study period.
Although Li said it is not very clear about the connection between exposure to power lines and asthma, he mentioned that prior studies by his team established a link between high exposure to electromagnetic fields and risk of miscarriages.
He also said that some animal studies indicated that electromagnetic field exposure can affect immune response, which could in turn predispose a person to asthma.
Dr Li suggested that daily, wide- spread exposure to magnetic fields (such as through home appliances) caused a serious public health concern.
He recommended that pregnant women minimize their exposure to known magnetic field sources .
Comments and Controversies
"That's a striking figure. That magnitude of association we don't see very often. If it was correct, and that's a big 'if,' that would be really startling" says David Savitz, PhD, a professor of community health and obstetrics and gynecology at Brown University in Providence
Savitz, said that unlike cigarette smoke or lead, there's little evidence that low-frequency EMFs (such as those measured in the study) are harmful.Therefore there is no need to give up using appliances such as air dryer just yet.
But Savitz and others recognize the importance of this research. "There are a lot of important topics that started out looking pretty flaky and pretty unlikely. There was a time when it made no sense that smoking could be bad for you," he remarks as other experts agree.
"The study appears to be well executed and the finding is surprising," says Jonathan M. Samet, MD, a pulmonologist and epidemiologist of the Keck School of Medicine at the University of Southern California in Los Angeles.
It must be remembered that Samet recently led a World Health Organization panel that came to the conclusion that EMFs from cell phones and other wireless devices could be carcinogenic.
De-Kun Li's study did not monitor exposure to higher frequency electromagnetic fields that are generated by mobile phones or mobile phone towers.
The study has drawn plenty of criticism too.
Professor of Paediatric Epidemiology at the University of Leeds, Patricia McKinney, said the study had several flaws.
"The investigation lacks a biological basis or hypothesis to test; papers cited in support of possible adverse effects of EMF (electromagnetic fields) on reproductive outcomes and the immune system are selective and ignore the major reviews which have concluded that the findings fail to provide a sufficiently strong case for any further investigation of this topic," McKinney said.
"Crucially, we cannot determine how representative the sample was - an important factor in epidemiological studies as this selection bias may have been linked to mothers who were more heavily exposed to EMF or likely to have children with asthma," McKinney added.
Visiting professor at University of Southampton, professor William Stewart observed that the study had several weaknesses in the way it measured magnetic fields and believed that the findings could be categorized as pure "chance".
The above topic has always been controversial and Li's study has suggested that there could be some connect between magnetic fields and human health.
De-Kun Li understands the need for more research to confirm his findings. This, he believes, would help in bringing out new strategies in dealing with the chronic disease, Asthma.