1. Division of Occupational and Environmental Health, Department of Environmental Health Sciences, Johns Hopkins UniversityBloomberg School of Public Health, Baltimore, Maryland, USA
2. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
3. Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
4. Department of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA
5. Institute of Industrial Medicine, SoonChunHyang University, Asan, South Korea
6. Lead Poisoning/Trace Elements Laboratory, Wadsworth Center, New York State Department of Health, Albany, New York, USA