1. Central American Institute for Studies on Toxic Substances (IRET), Universidad NacionalHeredia Costa Rica
2. Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of CaliforniaBerkeley CA
3. Division of Epidemiology, School of Public HealthUniversity of CaliforniaBerkeley CA
4. Division of Environmental Health Sciences, School of Public HealthUniversity of CaliforniaBerkeley CA
5. Department of Occupational MedicineInstitute of Environmental Medicine (IMM), Karolinska InstitutetStockholm Sweden