Study type: Epidemiological study (observational study)

Mobile phone use, blood lead levels, and attention deficit hyperactivity symptoms in children: a longitudinal study. epidem.

Published in: PLoS One 2013; 8 (3): e59742

Aim of study (acc. to author)

A cohort study was conducted in Korea to investigate the association between mobile phone use and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) considering the modifying effect of lead exposure.

Further details

The blood lead level was investigated as co-exposure because children exposed to relatively low levels of lead have inattention, cognitive loss and may develop Attention Deficit Hyperactivity Disorder.
The Korean version of the ADHD rating scale (K-ARS) was administered to parents or guardians to assess symptoms of the children in 2008 and 2010. A rating of 0-3 (depending on symptom severity) was used for each of the 18 questions and the results were summed. Total scores of ≥ 19 were regarded as positive for ADHD symptoms.

Endpoint/type of risk estimation

Type of risk estimation: (odds ratio (OR))

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 ownership of mobile phone: no
Group 2 ownership of mobile phone: yes
Reference group 3 age at first own of mobile phone: ≥ 11 years
Group 4 age at first own of mobile phone: 10 years
Group 5 age at first own of mobile phone: 9 years
Group 6 age at first own of mobile phone: 8 or less years
Reference group 7 number of sent text messages per day: no use
Group 8 number of sent text messages per day: 1 - 2
Group 9 number of sent text messages per day: ≥ 3
Reference group 10 number of outgoing calls per day: no use
Group 11 number of outgoing calls per day: 1 - 2
Group 12 number of outgoing calls per day: ≥ 3
Reference group 13 average time spent per voice call: no use
Group 14 average time spent per voice call: < 30 seconds
Group 15 average time spent per voice call: 30 seconds - < 1 minute
Group 16 average time spent per voice call: ≥ 1 minute
Reference group 17 cumulative time spent for voice call: 0 hours
Group 18 cumulative time spent for voice call: < 30 hours
Group 19 cumulative time spent for voice call: 30 - < 70 hours
Group 20 cumulative time spent for voice call: ≥ 70 hours
Reference group 21 average time spent for playing games on mobile phone per day: no use
Group 22 average time spent for playing games on mobile phone per day: 1 - 2 minutes
Group 23 average time spent for playing games on mobile phone per day: ≥ 3 minutes
Reference group 24 use of internet on mobile phone: no
Group 25 use of internet on mobile phone: yes

Population

Study size

Type Value
Participants 2,516
Evaluable 2,422
Other:

excluding children with incomplete questionnaire responses on mobile phone use or a lack of blood lead measurements in 2008 and 2010

Statistical analysis method: ( adjustment: )

Conclusion (acc. to author)

Ownership of a mobile phone (22.7 % in 2008 vs. 64.5 % in 2010) increased almost three times and the cumulative time spent for voice call use (1.36 hours in 2008 vs. 2.33 hours in 2010) increased almost two times over 2 years. The geometric mean level of blood lead (1.64 µg/dl in 2008 vs. 1.60 µg/dl in 2010) decreased slightly for the 2 years. The prevalence of ADHD symptoms in the present study was 10.4% in 2008 and 8.4% in 2010.
The ADHD symptom risk associated with mobile phone use for voice calls but the association was limited to children exposed to relatively high lead. The authors concluded that simultaneous exposure to lead and RF from mobile phone use was associated with increased ADHD symptom risk, although possible reverse causality could not be ruled out.

Study funded by

Related articles