Children of farmworkers in California are exposed to a unique mix of chemicals that may affect both their reproductive and neurobehavioral development. Potential exposures include the pesticide dichlorodiphenylthrichloroethane (DDT), which was recently used in Mexico where most of their farmworker parents originated;manganese (Mn), which is a key component of some widely used agricultural fungicides; and polybrominated diphenyl ether (PBDE) flame retardants, which are prevalent in California due to the state's strict flammability standards. DDT, Mn, and PBDEs are endocrine disruptors and neurotoxicants in animals, but studies in humans are limited. Age at onset of puberty in girls has declined in recent decades, possibly due to endocrine-disrupting compounds like DDT, Mn, and PBDEs, but almost no studies have examined pubertal onset in boys. These pollutants may also jeopardize children's cognitive development, particularly with exposure during the prenatal and peri-adolescent periods of peak brain growth. We propose to investigate the associations of DDT, Mn, and PBDE exposure in utero and at age 9 with puberty onset and neurodevelopment in the CHAMACOS longitudinal cohort of Mexican-American boys in the Salinas Valley, California. Boys enrolled in the CHAMACOS Study have been followed since before birth until 7 years of age. We will continue to follow these boys from age 9 to 13 years and enroll ~150 new 9 year-old-boys from the same source population, expanding the study from ~150 boys to 300. We have measured DDT and PBDE levels in prenatal maternal blood (original cohort) and will back-extrapolate prenatal levels from maternal blood collected at 9 years (new enrollees). Prenatal Mn exposure will be measured in boys'teeth. DDT, Mn, and PBDE concentrations at age 9 will be measured in boys'blood. We will assess the relationship of in utero (measured or extrapolated) and age 9 (measured) concentrations of DDT, Mn, and PBDEs with neurodevelopment (specifically general cognition, attention, memory, motor, executive function, and social cognition) and with the timing and tempo of their pubertal onset as assessed by clinical Tanner exams conducted every 9 months between age 9 and 13 years and hormone levels measured at 12 years. Thus, this proposal takes advantage of a rich dataset of Mexican-American children participating in the CHAMACOS longitudinal cohort study and proposes to expand this unique cohort and follow the children into early adolescence.

Public Health Relevance

This Study will examine the association of prenatal and childhood exposure to DDT, Mn, and PBDEs with neurodevelopment and pubertal development in boys. These exposures have relevance beyond farmworker children: PBDE exposure is nearly ubiquitous in the US;Mn is widely used as a fuel additive, in fungicides, and emitted industrially;and DDT use is increasing globally for malaria control. We aim to address key data gaps on the human health effects of these compounds crucial for assessing public health costs and benefits.

National Institute of Health (NIH)
National Institute of Environmental Health Sciences (NIEHS)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZES1-LKB-G)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California Berkeley
United States
Zip Code
Huen, Karen; Yousefi, Paul; Bradman, Asa et al. (2014) Effects of age, sex, and persistent organic pollutants on DNA methylation in children. Environ Mol Mutagen 55:209-22
Mora, Ana M; van Wendel de Joode, Berna; Mergler, Donna et al. (2014) Blood and hair manganese concentrations in pregnant women from the infants' environmental health study (ISA) in Costa Rica. Environ Sci Technol 48:3467-76
Dannemiller, K C; Mendell, M J; Macher, J M et al. (2014) Next-generation DNA sequencing reveals that low fungal diversity in house dust is associated with childhood asthma development. Indoor Air 24:236-47
Gunier, R B; Jerrett, M; Smith, D R et al. (2014) Determinants of manganese levels in house dust samples from the CHAMACOS cohort. Sci Total Environ 497-498:360-8
Chopra, Vidita; Harley, Kim; Lahiff, Maureen et al. (2014) Association between phthalates and attention deficit disorder and learning disability in U.S. children, 6-15 years. Environ Res 128:64-9
Alkon, Abbey; Harley, Kim G; Neilands, Torsten B et al. (2014) Latino children's body mass index at 2-3.5 years predicts sympathetic nervous system activity at 5 years. Child Obes 10:214-24
Rosas, Lisa G; Trujillo, Celina; Camacho, Jose et al. (2014) Acceptability of health information technology aimed at environmental health education in a prenatal clinic. Patient Educ Couns 97:244-7
Warner, Marcella; Wesselink, Amelia; Harley, Kim G et al. (2014) Prenatal exposure to dichlorodiphenyltrichloroethane and obesity at 9 years of age in the CHAMACOS study cohort. Am J Epidemiol 179:1312-22
Alkon, Abbey; Boyce, W Thomas; Tran, Linh et al. (2014) Prenatal adversities and Latino children's autonomic nervous system reactivity trajectories from 6 months to 5 years of age. PLoS One 9:e86283
Eskenazi, B; Bradman, A; Finkton, D et al. (2013) A rapid questionnaire assessment of environmental exposures to pregnant women in the INTERGROWTH-21st Project. BJOG 120 Suppl 2:129-38, v

Showing the most recent 10 out of 99 publications