2015 Progress Report: Project B: Exposure Project: Mn, DDT/E and PBDE Exposure to Farmworker Children

EPA Grant Number: R834513C002
Subproject: this is subproject number 002 , established and managed by the Center Director under grant R834513
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Center for the Health Assessment of Mothers and Children of Salinas - UC Berkeley School of Public Health: CHAMACOS Office, Berkeley, CA
Center Director: Eskenazi, Brenda
Title: Project B: Exposure Project: Mn, DDT/E and PBDE Exposure to Farmworker Children
Investigators: Eskenazi, Brenda , Arora, Manish , Bradman, Asa , Harley, Kim , Holland, Nina T. , Jerrett, Michael , Molitor, John , Sjodin, Andreas , Smith, Donald
Institution: University of California - Berkeley , Centers for Disease Control and Prevention , Mount Sinai School of Medicine , Oregon State University , University of California - Santa Cruz
EPA Project Officer: Louie, Nica
Project Period: August 1, 2009 through July 31, 2014 (Extended to July 31, 2016)
Project Period Covered by this Report: June 1, 2014 through May 31,2015
RFA: Children's Environmental Health and Disease Prevention Research Centers (with NIEHS) (2009) RFA Text |  Recipients Lists
Research Category: Children's Health , Health

Objective:

In Project B, we are examining novel methods of examining prenatal exposure to Mn, PBDE, and DDT/E compounds. For Mn, we are developing methods to measure Mn in shed deciduous teeth and in hair collected when the children were 10.5 years of age. For PBDEs and DDT/E, we are developing models to back-extrapolate prenatal exposure levels from 9-year measured levels and other determinants of exposure.

Progress Summary:

Specific Aim 1. To measure Mn, PBDEs, and DDT/E in shed deciduous teeth. (Population: CHAMACOS children participating since birth.)

Mn: We have successfully developed a method for measuring Mn in human teeth by laser ablation ICP-mass spectrometry (LA/ICP/MS), including analysis of 307 teeth collected from the CHAMACOS cohort. Rather than calculate one estimate of cumulative exposure over the entire prenatal period, we have used a method to distinguish Mn exposure experienced in the 2nd trimester from that experienced in the 3rd trimester. We observed a significant association (rspearman = 0.36, p = 0.001, n = 77) between Mn levels in the entire prenatally-formed dentine [as defined by 55Mn:43Ca area under the curve (AUC)] with floor dust Mn loading (μg Mn/m2 floor area) and a stronger relationship with Mn levels in dentine formed only in the 2nd trimester (rspearman = 0.40; p = 0.0005; n = 72), likely because dust samples were collected in the 2nd trimester. We have also compared Mn levels in cord blood and mantle dentine. While there was no significant association of 55Mn:43Ca AUC of all prenatal sampling points with cord blood Mn (rspearman = -0.01; p = 0.99), 55Mn:43Ca in the sampling point immediately adjacent to the neonatal line in each tooth showed a significant positive correlation with cord blood Mn (rspearman = 0.70; p = 0.003; n = 16). These findings were published in Environmental Science & Technology (Arora, et al., 2012) and the measurements were used in subsequent studies examining exposure and health outcomes.

PBDEs and DDT/E: As a pilot investigation, we assessed the feasibility of measuring persistent organic pollutants in deciduous teeth. Dr. Andreas Sjödin at the CDC in Atlanta attempted to measure PBDEs and DDT in anonymous deciduous teeth collected from dental patients demographically similar to the CHAMACOS cohort. Using whole tooth digestion, neither PBDEs nor DDT were detected. Additional anonymous deciduous teeth were obtained from a local clinic and Dr. Arora extracted the dentine from these teeth to determine if more sensitive analyses could be employed to measure PBDEs and organochlorine (OC) compounds including DDT. Initial results were not promising. Specifically, low detection frequencies for the typically prevalent congeners PBDE-47 and -99 and high concentrations of PBDE-183 for all samples suggested possible contamination with PBDE-183. One challenge in the interpretation of xenobiotic measurements in dentine is the likelihood that dentine tissue, which is vasculated, may be in equilibrium with child exposures when the teeth are shed and may not reflect prenatal exposures. Some compounds, such as metals, are incorporated into the chemical structure of the dentine, but many organic compounds are not. Additional research is needed to broadly screen for chemicals in dentine strata and validate measurements against maternal and child biomonitoring.

Specific Aim 2. To determine the relationship between Mn, PBDE, and DDT/E levels in teeth with other relevant biological measures.

For a subset of CHAMACOS participants, we conducted laboratory measurements of Mn in multiple biological samples, including 202 whole blood samples (maternal blood, cord blood, child’s blood), 128 urine samples (maternal at 26-week gestation and child at 24 months), and 62 teeth and examined the interrelationships of Mn levels in all matrices.

Mn levels (Mn:Ca ratio) were higher in prenatal than postnatal dentine (geometric mean (GM) = 0.51 vs. 0.16, p < 0.0001). Maternal blood Mn concentrations increased from 26 weeks gestation to delivery (GM = 14.6 to 20.7 μg/L, p = 0.001) and child blood Mn concentrations decreased from cord blood to 24-month blood samples (39.9 vs. 25.0 μg/L, p = 0.005). Mn levels in tooth dentine during the 3rd trimester were positively correlated with Mn concentrations in cord blood (rs = 0.31), while there was a negative correlation between prenatal Mn levels in enamel and concentrations in maternal blood at 26-weeks’ gestation (rs = -0.36). We did not find any significant differences in Mn urine concentrations over time and did not observe significant correlations between Mn levels in teeth and urine, suggesting that urinary concentrations are not a useful measure of environmental Mn exposure.

We observed significantly higher (p < 0.05) levels of Mn in prenatal dentine, prenatal maternal blood, and 24-month urine from children if there was a farm worker living in the home during the corresponding time period compared to no farmworker living in the home. Prenatal Mn levels in dentine and cord blood were also correlated with Mn loading in prenatal house dust samples (rs = 0.27 and 0.29, respectively; p < 0.1). Tooth dentine and blood Mn concentrations had the strongest associations with potential sources of Mn exposure in the home. These findings were published in Environmental Science & Technology (Gunier, et al., 2014).

Specific Aim 3. To quantify the contribution of agricultural pesticide use to Mn levels in house dust, teeth, hair and child blood.

Mn in dust: We collected house dust samples from 378 CHAMACOS participant residences, with a second sample collected approximately nine months later from 90 of the residences. House dust samples were analyzed for Mn using inductively coupled plasma optical emission spectroscopy. Information from interviews, home inspections, and pesticide use reports was used to identify potential predictors of Mn dust concentrations and loadings. Mn was detectable in all dust samples. The median Mn concentration was 171 μg/g and median Mn loading was 1,910 μg/m2 at first visit. In multivariable models, Mn dust concentrations and loadings increased with the number of farmworkers in the home and the amount of agricultural Mn fungicides applied within three kilometers of the residence during the month prior to dust sample collection. Dust concentrations of Mn and other metals (lead, cadmium and chromium) were higher in residences located in the southern Salinas Valley compared to those located in other areas of the Salinas Valley. Dust loadings of Mn and other metals were also higher in residences located on Antioch Loam soil than other soil types, and in homes with poor or average housekeeping practices (Figure 1).

Agricultural use of Mn-containing fungicides was associated with Mn dust concentrations and loadings in nearby residences and farmworker homes. Housekeeping practices and soil type at residence were also important factors related to dust metal concentrations and loadings. These findings were published in Science of the Total Environment (Gunier, et al., 2014).

Mn in teeth: We examined environmental and lifestyle factors associated with prenatal tooth dentine Mn concentrations for 207 CHAMACOS children.We found that storage of farmworkers’ shoes in the home, maternal farm work, agricultural use of Mn-containing fungicides within 3 km of the residence, residence built on Antioch Loam soil and Mn dust loading (μg/m2 of floor area) during pregnancy were associated with higher Mn levels in prenatal dentine (p < 0.05). Maternal smoking during pregnancy was inversely related to Mn levels in prenatal dentine (p < 0.01). Multivariable regression models explained 22-29% of the variability of Mn in prenatal dentine (Table 1).

Our results suggest that Mn measured in prenatal dentine provides retrospective and time-specific levels of fetal exposure resulting from environmental and occupational sources. These findings were published in Environmental Science & Technology (Gunier, et al., 2013).

Mn in hair: In the absence of a validated methodology for the accurate determination of hair Mn without external contamination, we developed and validated a method to analyze Mn in hair which included thorough sample cleanup, showing in the process that prior published studies of hair Mn are likely erroneous (Eastman, et al., 2013). We have collected hair samples from 455 children (145 boys and 310 girls). Due to costs associated with the extensive cleanup procedure necessary to analyze the hair properly, we were only able to analyze hair from a subsample of children. Dr. Smith at UCSC has analyzed samples from 135 participants. The Mn hair concentrations in our cohort were similar to the only other published study using the same cleaning methodology, which focused on children exposed to Mn through proximity to a ferroalloy plant (Eastman, et al., 2013). In bivariate analyses, we found that Mn hair concentrations were related to location of the hair sample soil type at the child’s residence, location of the residence in the Southern portion of Monterey County and agricultural use of Mn fungicides within 3 km of the child’s residence during the 6 months prior to sample collection. Hair Mn concentrations were not related to demographic variables, the presence of agricultural workers in the home or the use of hair care products prior to sample collection. Location of hair sample, residence in Southern Monterey County and agricultural use of Mn fungicides near the child’s residence remained significant in multivariate models. In preliminary analyses, we did not observe an association between hair Mn concentrations and 10.5 year IQ or behavior in models adjusted for child’s exact age, maternal education, poverty status, language of assessment and HOME score. We are currently preparing a manuscript for publication on our Mn hair analyses.

Specific Aim 4. To identify population correlates of PBDEs and DDT/E exposure in 9-year-old boys.

CDC has analyzed CHAMACOS blood samples for PBDEs, DDT/E and PCBs in 412 mothers during pregnancy, 277 children at the 7-year visit, and 145 mothers and 552 children at the 9-year visit. The geometric means for these compounds decreased in the children from age seven to nine years. Assuming that at least in the case of PCB-153 and p,p’-DDE there has not been a meaningful decrease in dietary intake during the time period investigated, it is assumed that the decrease observed is mainly related to dilution from an increasing body mass with age. This hypothesis is supported by a significant correlation between percent weight increase and percent decreased serum concentration between seven and nine years of age. Dr. Andreas Sjodin is preparing a manuscript examining determinants of PBDE and DDT/E exposures in 9-year-olds. The statistical analysis for this paper is complete and includes comparison of the CHAMACOS serum concentration data with a published cohort of Texas children (Sjodin, et al., 2014). CHAMACOS participants had significantly higher exposures to PBDEs than children from Texas. Concentrations of PCB-153 were comparable in the CHAMACOS and Texas children while p,p’-DDE concentrations were higher in the primarily Mexican population of the CHAMCOS cohort.

Back-extrapolation of DDT/E and PBDEs: We evaluated three modeling approaches (physiologically-based pharmacokinetic modeling (PBPK), deletion substitution algorithms, and SuperLearner) to estimate maternal DDT/E and PBDE exposures during pregnancy when measurements were collected from the mothers nine years after birth. To accomplish this, we used the models to predict serum levels measured at 26 weeks gestation in the pregnant mothers (n = 161) from levels measured in the mothers and the child when the child was 9. For each model, we assessed whether the nine-year maternal (n = 94) or child (n = 161) measurements alone, or levels in both mothers and children (n = 89) at age nine, predicted the levels in the mothers during pregnancy. Model performance was assessed using the root mean squared error (RMSE) and coefficient of determination (R2) of log10-transformed back-extrapolated versus measured levels. For all compounds and subsets, SuperLearner outperformed the other approaches with RMSEs and R2s ranging from 0.10-0.31 log10 ng/g and 0.58-0.97, respectively. Typically, model RMSEs were lower and R2s were higher for p,p’-DDT/E than PBDE congeners, and estimations using maternal levels (when their child was 9 years) were more accurate for back extrapolation to pregnancy levels than using child levels at 9 years. The PBPK model performed well but not as well as SuperLearner when back-extrapolating prenatal levels from maternal levels for compounds with longer half-lives such as p,p’-DDE and BDE-153 (RMSEs= 0.21 and 0.28 log10 ng/g and R2s= 0.88 and 0.57, respectively). Overall, our results demonstrate the ability to accurately back-extrapolate prenatal levels from maternal levels 9 years after delivery, with SuperLearner performing the best based on our fit criteria. These findings were published in Environmental Science & Technology (Verner, et al., 2015).

OTHER CHAMACOS STUDIES

  • DAPs in child urine. A manuscript examining changes in pesticide excretion during organic food intake was published in Environmental Health Perspectives (Bradman, Quiros-Alcala, et al., 2015).
  • Occupational Take-home Exposures: An article on reducing exposures to farmworkers’ children was published in the Journal of Environmental Epidemiology and Exposure Science (Salvatore, et al., 2015).

Significance

The work completed as part of Project B of this Children’s Center grant advanced the field of exposure science in several ways. We evaluated a novel biomarker of perinatal Mn exposure by conducting detailed studies measuring Mn in dentine of children’s teeth and then characterizing prenatal and early postnatal sources of Mn exposure to evaluate dentine as a retrospective biomarker of exposure to Mn. This evaluation was only possible due to the wealth of stored environmental and biological samples available from the CHAMACOS cohort and the availability of Pesticide Use Data in California. In this first large-scale study of Mn exposure in children living in an agricultural region, we demonstrated that Mn in dentine was related to agricultural sources of Mn, including nearby agricultural use of Mn-fungicides using state of the art GIS modeling techniques, as well as Mn levels in house dust and the presence of agricultural workers living in the home. We were also able to show Mn levels in dentine provided estimates that were specific to the prenatal and early postnatal periods, which are critical time periods of development. We used stored house dust samples from the prenatal period to measure Mn concentrations and calculate Mn dust loadings that established home Mn contamination from agricultural sources as a likely pathway of exposure. We observed associations between nearby agricultural Mn-fungicide use, soil type at the residence and location of the residence and both concentrations and loading of Mn in house dust which not only identified Mn-fungicide use as a possible source of environmental Mn exposure, but further demonstrated the contamination of homes in agricultural communities from nearby pesticide use and the take-home pathway for farmworker families.

Our preliminary analyses of Mn concentrations in hair samples that were thoroughly cleaned prior to laboratory measurements indicate that this exposure biomarker is also related to nearby agricultural Mn-fungicide use and provides a promising non-invasive method of exposure assessment. In addition, in the course of this analysis, we have developed methodology for hair processing that will yield more valid measures of various exposures using this matrix.

With the benefit of stored prenatal blood samples that were used to evaluate prediction models, we developed novel methods to determine PBDE and DDT/E exposures during the prenatal period from blood samples collected 9-years later and identified important predictors of changes in blood levels of these compounds. Our preliminary analyses indicate that PBDE blood concentrations have declined in children after the removal of these compounds from consumer products in California. This study is important because it provides a basis for utilizing cross-sectional enrollment of children but allowing retrospective exposure assessment to improve the feasibility and statistical power of studies examining prenatal exposures and child health outcomes.

Finally, we published data from the CHAMACOS study demonstrating that exposure to organophosphate pesticides can be reduced in women and children through interventions that include providing an organic diet and educating farmworkers to remove clothes and wash hands prior to entering their homes. These studies could not have been conducted without the participation of this unique population of Mexican-American women and children who by virtue of being immigrants and farmworkers have high exposures to the California mixture of chemicals, i.e., to DDT from use in Mexico, to PBDEs from living in California, and to Mn due to heavy regional use of Mn-containing fungicides.

Future Activities:

In the next year, we will complete analyses of correlates of PBDE and DDT/E exposure in children. We also will complete analyses of determinants of Mn concentrations in hair at 10.5 years of age. We expect to submit at least two manuscripts this year on correlates of PBDEs and DDT/E in children and determinants of Mn concentrations in hair.


Journal Articles on this Report : 11 Displayed | Download in RIS Format

Other subproject views: All 103 publications 38 publications in selected types All 37 journal articles
Other center views: All 666 publications 138 publications in selected types All 137 journal articles
Type Citation Sub Project Document Sources
Journal Article Bradman A, Quiros-Alcala L, Castorina R, Schall RA, Camacho J, Holland NT, Barr DB, Eskenazi B. Effect of organic diet intervention on pesticide exposures in young children living in low-income urban and agricultural communities. Environmental Health Perspectives 2015;123(10):1086-1093. R834513 (2014)
R834513 (Final)
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  • Journal Article Gaspar FW, Castorina R, Maddalena RL, Nishioka MG, McKone TE, Bradman A. Phthalate exposure and risk assessment in California child care facilities. Environmental Science & Technology 2014;48(13):7593-7601. R834513 (2014)
    R834513 (Final)
    R834513C002 (2014)
    R834513C002 (2015)
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  • Journal Article Gunier RB, Mora AM, Smith D, Arora M, Austin C, Eskenazi B, Bradman A. Biomarkers of manganese exposure in pregnant women and children living in an agricultural community in California. Environmental Science & Technology 2014;48(24):14695-14702. R834513 (2011)
    R834513 (2013)
    R834513 (2014)
    R834513 (2015)
    R834513 (Final)
    R834513C002 (2014)
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    R834513C004 (2011)
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  • Journal Article Gunier RB, Jerrett M, Smith DR, Jursa T, Yousefi P, Camacho J, Hubbard A, Eskenazi B, Bradman A. Determinants of manganese levels in house dust samples from the CHAMACOS cohort. Science of the Total Environment 2014;497-498:360-368. R834513 (2012)
    R834513 (2013)
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    R834513C002 (2010)
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  • Journal Article Harley KG, Kogut K, Madrigal DS, Cardenas M, Vera IA, Meza-Alfaro G, She J, Gavin Q, Zahedi R, Bradman A, Eskenazi B, Parra KL. Reducing phthalate, paraben, and phenol exposure from personal care products in adolescent girls: findings from the HERMOSA Intervention Study. Environmental Health Perspectives 2016;124(10):1600-1607. R834513 (Final)
    R834513C002 (2015)
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  • Journal Article Macher JM, Mendell MJ, Kumagai K, Holland NT, Camacho JM, Harley KG, Eskenazi B, Bradman A. Higher measured moisture in California homes with qualitative evidence of dampness. Indoor Air 2016;26(6):892-902. R834513 (Final)
    R834513C002 (2015)
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  • Journal Article Mora AM, van Wendel de Joode B, Mergler D, Cordoba L, Cano C, Quesada R, Smith DR, Menezes-Filho JA, Lundh T, Lindh CH, Bradman A, Eskenazi B. Blood and hair manganese concentrations in pregnant women from the Infants’ Environmental Health Study (ISA) in Costa Rica. Environmental Science & Technology 2014;48(6):3467-3476. R834513 (2014)
    R834513 (Final)
    R834513C001 (2014)
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    R834513C002 (2015)
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  • Journal Article Salvatore AL, Castorina R, Camacho J, Morga N, Lopez J, Nishioka M, Barr DB, Eskenazi B, Bradman A. Home-based community health worker intervention to reduce pesticide exposures to farmworkers’ children: a randomized-controlled trial. Journal of Exposure Science & Environmental Epidemiology 2015;25(6):608-615. R834513 (2014)
    R834513 (2015)
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  • Journal Article Sjodin A, Jones RS, Gunier RB, Wong LY, Holland N, Eskenazi B, Bradman, A. Polybrominated diphenyl ethers, polychlorinated biphenyls, and 2,2-Bis(4-chlorophenyl)-1,1-dichloroethene in 7-and 9-year-old children and their mothers in the Center for the Health Assessment of Mothers and Children of Salinas Cohort. Environmental Science & Technology 2018;52(4):2287-2294. R834513 (Final)
    R834513C002 (2015)
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  • Journal Article van Wendel de Joode B, Mora AM, Cordoba L, Cano JC, Quesada R, Faniband M, Wesseling C, Ruepert C, Oberg M, Eskenazi B, Mergler D, Lindh CH. Aerial application of mancozeb and urinary ethylene thiourea (ETU) concentrations among pregnant women in Costa Rica: the Infants’ Environmental Health Study (ISA). Environmental Health Perspectives 2014;122(12):1321-1328. R834513 (2014)
    R834513 (Final)
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  • Journal Article Verner M-A, Gaspar FW, Chevrier J, Gunier RB, Sjodin A, Bradman A, Eskenazi B. Increasing sample size in prospective birth cohorts:back-extrapolating prenatal levels of persistent organic pollutants in newly enrolled children. Environmental Science & Technology 2015;49(6):3940-3948. R834513 (2014)
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  • Supplemental Keywords:

    DDT, DDE, PBDEs, flame retardants, manganese, maneb, mancozeb, pesticides, exposure assessment, biomonitoring, house dust, dust loading, teeth, blood, urine measurements, RFA, Health, Scientific Discipline, INTERNATIONAL COOPERATION, Health Risk Assessment, Children's Health, Environmental Policy, Biology, farmworkers, pesticide exposure, flame retardants, PBDE, children's vulnerablity, neurochemical effects, harmful environmental agents, biological markers, agricultural community

    Relevant Websites:

    Center for Environmental Research and Children's Health (CERCH) Exit

    Progress and Final Reports:

    Original Abstract
  • 2010 Progress Report
  • 2011 Progress Report
  • 2012 Progress Report
  • 2013 Progress Report
  • 2014 Progress Report
  • Final

  • Main Center Abstract and Reports:

    R834513    Center for the Health Assessment of Mothers and Children of Salinas - UC Berkeley School of Public Health: CHAMACOS Office, Berkeley, CA

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R834513C001 CHAMACOS Cohort Project: Pesticides and PBDE on Neurobehavior and Puberty
    R834513C002 Project B: Exposure Project: Mn, DDT/E and PBDE Exposure to Farmworker Children
    R834513C003 Epigenetics Project
    R834513C004 Community Outreach and Translation Core