Health Outcomes Studies

CHAMACOS is a longitudinal birth cohort study, meaning that we enrolled a group of children before they were born and are following them as they grow up to study their health and development.

What the CHAMACOS Health Outcomes Study investigates:

Initially, the CHAMACOS  Study focused on the health impacts of children’s exposure to pesticides.  In recent years, the scope has expanded to include other common environmental chemicals that may affect children’s health, growth or brain development.

Exposures we have examined:

  • Pesticides
    • Organophosphates
    • Organochlorines (e.g., DDT)
    • Pyrethroids
    • Manganese-containing fungicides
  • Flame retardants (including PBDEs)
  • Components of plastics (Bisphenol A, Phthalates)
  • Allergens
  • Social factors like neighborhood environment and housing quality

Health outcomes we have examined:

  • Birth weight
  • Neurodevelopment and behavior (e.g., cognition, ADHD)
  • Timing of puberty
  • Hormonal function
  • Obesity
  • Asthma
  • Immune function

Findings from the CHAMACOS Health Outcomes Study: (Go to Findings)


  • The Salinas Valley, CA
    • One of the world’s richest agricultural areas, producing more than 35 different crops.
    • The mild climate and long growing season mean that the local farmworker population is relatively stable.
    • The Salinas Valley is often referred to as the “nation’s salad bowl,” growing primarily grapes, strawberries, lettuces, artichokes, and broccoli.

Study Participants:

  • All CHAMACOS children were born between 2000 and 2002.
  • The original CHAMACOS participants were enrolled when the mothers were pregnant.  A new group of participants joined the cohort at age 9.
  • Originally, 601 mothers were enrolled and followed through to the birth of 536 infants .
  • At age 9 years, 336 of these children were still being followed in the study.
  • In 2010-11, another 300 9-year-old children were enrolled, bringing the total study population of ~600 children currently enrolled (2011).
  • To be eligible for CHAMACOS, at the time of the pregnancy mothers needed to be:
    • Spanish or English speaking
    • ≥ 18 years old
    • Eligible for low-income health insurance (MediCal)
    • Planning to deliver at Natividad Medical Center (NMC)
  • CHAMACOS mothers are primarily young, married, low-income, Mexican-born, and Spanish-speaking.  During their pregnancy, about 44% were farmworkers  themselves and 84% lived with a farmworker.

Data Collection:

  • Half of the CHAMACOS children have grown up making regular visits to the CHAMACOS field office in Salinas.  Mothers were interviewed and children were assessed twice during pregnancy, shortly after delivery, and when the child was 6 months and 1, 2, 3½, 5, 7 and 9 years old.  The other half of the children joined the study at age 9 and will continue with the cohort into adolescence.  We are currently performing the 10½ year-old visit, and are preparing to assess the children again at 12 years of age.
  • Most visits have consisted of:
    • a maternal interview,
    • a neurodevelopmental assessment of the child,
    • a physical exam of the child
    • a home inspection, and
    • collection of biological and environmental samples (such as urine, blood, and house dust).
  • All study activities are conducted by trained bilingual, bicultural study staff from the local Salinas community. Assessments were conducted in the CHAMACOS field office, located at Natividad Medical Center.
  • CHAMACOS Biological and Environmental Specimen Collection Chart:
Specimen Collection 1st Tri 2nd Tri Delivery 6 M 1 Y 2 Y 3.5 Y 5 Y 7 Y 9 Y 10.5 Y 12 Y
Maternal Urine X X X X X
Paternal Urine X
Maternal Blood X X X
Cord Blood X
Breast Milk X X
Child Urine X X X X X X
Child Blood X X X X X X
Child Teeth X X X
Child Saliva X X
Child Hair X
House Dust X X X


  • CHAMACOS Data Collection Chart:
Data Collection 1st Tri 2nd Tri Delivery 6 M 1 Y 2 Y 3.5 Y 5 Y 7 Y 9 Y 10.5 Y 12 Y
Maternal Questionnaire X X X X X X X X X X X X
Home Inspection X   X X X X X
Neurodevelopmental Assessment   X X X X X X X X X X
School Performance   X
Physical Exam X X X X X X X X*2 X*2 X*2
Tanner Staging         X*2 X*2 X*2
Respiratory Function X X  


Community Partners:

  • Natividad Medical Center
  • Clinica de Salud del Valle de Salinas
  • Learn more about our Community Partners here.

Research Team:

  • Brenda Eskenazi, PhD
  • Kim Harley, PhD
  • Asa Bradman, PhD
  • Nina Holland, PhD
  • Robert Lustig, MD, University of California, San Francisco
  • Ellen Eisen, ScD
  • Katie Kogut, MPH, MSc
  • Jonathan Chevrier, PhD
  • Michelle Gubatina Vedar, MPH
  • Lesliam Quirós Alcalá, PhD MS
  • Raul Aguilar Schall, PhD
  • Ana Maria Mora, MD, MPH
  • Kristin Tyler
  • Celina Trujillo, MPH
  • Norma Calderon
  • Hedy Hernandez
  • Johanna Camacho
  • Jose Camacho
  • Kimberly Parra
  • Diana Villanueva
  • Caroline Johnson, PhD
  • Alan Hubbard, PhD
  • Marc Tunzi, MD, Natividad Medical Foundation
  • Maximilliano Cuevas, MD, Clinica  de Salud del Valle de Salinas


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