Research
Center for the Health Assessment of Mothers and Children of Salinas

The Center’s research is focused on four core areas of investigation:

CHAMACOS Cohort Study

CHAMACOS Intervention Studies

Pesticide Exposure Studies

Mechanism Studies

Intervention crew

  1. CHAMACOS Cohort Study

    2. The CHAMACOS Cohort study is a longitudinal birth cohort study that has followed a population of children from before birth through age 7. The goal of this on-going study is to assess the health effects of low-level, chronic pesticide exposure and other exposures in children living in an agricultural community. The study population is comprised of 536 infants, born in 2000-2001, whose mothers were enrolled during pregnancy. Exposure to pesticides and other environmental contaminants was assessed in material urine plus blood samples during pregnancy and in child samples at birth, 6 months, 1, 2, 3˝, 5 and, currently, 7 years of age. The children have been examined at each of these ages to assess their growth, neurodevelopment, respiratory disease, and general health.

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  2. CHAMACOS Intervention Studies

    3. The Center has implemented two community-based participatory intervention research studies. The goal of these intervention studies is to develop sustainable methods for reducing pesticide exposures to farmworkers and their children. In particular, we are interested in reducing “take home” exposures (i.e. pesticides on the parents’ clothing, shoes, and skin that are transported from the fields into the home). Our community partners and farmworker leaders played a key role in developing these interventions.

    • Field-based Technical Intervention: Working with strawberry growers in the Salinas Valley, we developed a technical intervention that was implemented with farmworkers in the fields. This intervention was a randomized trial that compared a control group of farm workers in normal work conditions with an intervention group of workers that received educational sessions, coveralls, gloves, and warm water for handwashing. The control group received a comparable intervention after all final data collection activities ended. Our grower collaborators were permitted to keep the water heater at the end of the study.

      • Intervention crew

    • Home-based Educational intervention: The home-based intervention with farmworker households consisted of three visits over three months by a team of trained, bilingual Environmental Health Promoters (EHPs) from the community. During the home visits EHPs provided educational sessions to participants and other household members and assisted them in developing a household action plan to reduce pesticide exposure. This intervention was a randomized control trial and included both an intervention group and a control group.

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  3. Pesticide Exposure Studies

    4. The goals of these studies are to identify child-specific pathways of pesticide exposure and to validate methods of exposure measurement in pregnant women and children. Specific exposure studies conducted by the Children’s Center at UC Berkeley are as follows:


    Researcher

    • Quantitative Exposure Analysis (QEA) Study: Conducted in 2002, the goal of the QEA was to quantify the relative contributions of diet and ambient household exposures to infant and toddler pesticide loads. Twenty children participated in this intensive study, ten between 5 and 11 months of age and ten between 21 and 27 months of age. Data collection included an exposure questionnaire for parents, a home inspection form, 24-hour food diaries, and 24-hour child time-activity logs. Pesticide levels were measured in indoor and outdoor air samples, in indoor dust, and on floors in the household. To explore the contribution of children’s crawling, walking, and hand-to-mouth activities on exposure levels, pesticide levels were also measured on union suits and socks worn by the child and on teething objects or toys. Children’s pesticide load was measured through pesticide metabolite levels in urine.
    • Child Validation Study (CVS): Conducted in 2004, the purpose of the CVS was to validate the use of urinary dialkylphosphate (DAP) metabolite measures from one-void-only urine sampling (“spot sampling”) as an appropriate proxy for measures in 24-hour urine samples, considered the gold standard measurement. Twenty-five 3- to 5-year-old children participated in a 7-day sampling regimen, which included daily spot-sampling, two 24-hr samples, and two first morning voids. Parents completed an initial exposure questionnaire and home walkthrough, as well as a brief daily diet and exposure questionnaire.
    • Organic Diet Trial: Twenty families in the agricultural Salinas Valley, CA and twenty families in urban Oakland, CA were provided with organic food for 7 days. Metabolites of OP pesticides were measured in the urine of the preschool aged children every day during the conventional food and organic food portions of the trial. By comparing similar populations living in urban and agricultural areas, this study will help us determine the relative contribution of diet and ambient exposures to pesticide levels in young children.
    • Peripartum Study: This study will enroll women during pregnancy and measure their urinary and blood pesticide levels before and after delivery, to learn more about the pharmacokinetics of OP pesticide metabolism in pregnant mothers.

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  4. Mechanism Studies

    5. These lab-based studies take advantage of the large repository of biological samples from the CHAMACOS cohort to explore the mechanisms of pesticide immunotoxicity and neurotoxicity and to elucidate differences in susceptibility to pesticides through gene-environment interaction.

    • Immunotoxicity: Researchers are using in vitro cultures of human cells to examine the effects of individual and combined exposures to pesticides, endotoxin, and allergens on cytokine response. We are also examining levels of intracellular Th1 and Th2-type cytokines in whole blood collected from members of the CHAMACOS cohort at 1, 2, and 5 years of age to examine the effects of these exposures in vivo.
    • Neurotoxicity: Researchers are examining the role of neurotoxic target esterase (NTE) activity in neurotoxicity in a neuroblastoma cell line and in human lymphocytes using a new method based on interaction with a cellular target (lysophospholipids).
    • PON1 as a Predictor of Pesticide Susceptibility: Given the same level of pesticide exposure, some individuals may be more susceptible to the potential adverse effects of pesticides depending on their genetic makeup and expression of genes encoding key metabolic enzymes. For example, the human enzyme paraoxonase (PON1) detoxifies various organophosphate pesticides with different efficiency depending on the main single nucleotide polymorphism (SNP) at position 192 and other SNPs along promoter and coding regions.

    The pesticide susceptibility project is determining PON1 genotype for two polymorphisms (192 and –108) and measuring enzyme activity levels (paraoxonase, diazoxonase, chlorpyrifos oxonase, and arylesterase) in maternal and child blood from the CHAMACOS cohort. We will also examine whether PON1 status modifies the association of pesticides and neurodevelopment.

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