By Kim Tae-gyu

A state-run research agency is conducting a study on whether overuse of mobile phones might have something to do with the attention deficit hyperactivity disorder (ADHD) in children.

The Electronics and Telecommunications Research Institute (ETRI) said Monday that it had conducted a study on thousands of local elementary school students from 2008 through 2010.

``We checked 2,000 students across the country to learn that the longer they used cell phones, the bigger the probability was that they suffered from ADHD,’’ an ETRI official said.

``But we are not sure whether the correlation is caused by the electromagnetic field. We will draw a final conclusion through follow-up research.’’

ADHD refers to a problem of inattentiveness, over-activity, impulsivity or a combination of these, which has become a big social issue over the past several years.

The childhood behavioral disorder, which takes place more often in boys than girls, is believed to affect up to 5 percent of schoolchildren and the rate has appeared to have increase of late.

However, the institute did not reveal detailed data as the research has yet to be completed ― it plans to make these public through a paper that will be presented to the U.S. journal Epidemiology later this year.

ETRI also commented on other research on the rate at which children absorb energy from electromagnetic fields, dubbed the specific absorption rate (SAR), compared to adults.

Imaging studies on children aged up to seven, ETRI said that children showed a higher SAR in the 100MHz and higher than 1GHz frequencies.

The former is used for radios while the latter is for mobile telephony services. In other words, the implication is that children are more vulnerable to electromagnetic fields.

``We will have to rethink about the global references and action levels for children’s electromagnetic exposure. We may have to strengthen previous benchmarks for the specific frequencies in question,’’ the official said.

``More fundamentally, we may have to create systemic measures to prevent children from the threat of electromagnetic exposure.’’

With regard to pregnant women’s use of handsets, ETRI said that they did not affect babies unlike previous research hinted at in a study in Denmark.

``We do not have a smoking gun to prove the electromagnetic field negatively affects our bodies. But we cannot conclude that they are not correlated,’’ the official said. ``We plan to continue our study on the issue.’’