Grantee Research Project Results
2002 Progress Report: Meconium Analysis - A Promising Tool to Detect Fetal Exposure to Environmental Toxins
EPA Grant Number: R829395Title: Meconium Analysis - A Promising Tool to Detect Fetal Exposure to Environmental Toxins
Investigators: Ostrea, Enrique M. , Bielawski, Dawn , Villanueva-Uy, Esterlita , Ager, Joel
Institution: Wayne State University
EPA Project Officer: Aja, Hayley
Project Period: April 1, 2002 through April 1, 2006
Project Period Covered by this Report: April 1, 2002 through April 1, 2003
Project Amount: $726,411
RFA: Children's Vulnerability to Toxic Substances in the Environment (2001) RFA Text | Recipients Lists
Research Category: Children's Health , Human Health
Objective:
The overall objective of this research project is to develop meconium analysis as a sensitive, diagnostic tool to detect fetal exposure to environmental toxins (heavy metals and pesticides). The specific objectives of the research project are to: (1) compare the prevalence and amount of fetal exposure to environmental toxins through the analysis of meconium, cord blood, and neonatal hair and to determine the degree of agreement among these methods; and (2) determine the relationship between maternal exposure to environmental toxins during pregnancy, as determined by serial analyses of maternal hair and blood and the positivity rate and concentrations of environmental toxins in meconium, cord blood, and neonatal hair. The hypotheses for this research are: (1) meconium analysis will detect a higher prevalence and amount of fetal exposure to environmental toxins as compared to cord blood or neonatal hair analyses; (2) there will be a positive relationship between meconium analysis and cord blood or neonatal hair analyses on the prevalence and amount of fetal exposure to environmental toxins; and (3) the prevalence and amount of maternal exposure to environmental toxins, as determined by maternal hair and blood analyses, will correlate more to the prevalence and amount of fetal exposure to environmental toxins, as determined by meconium analysis, compared to cord blood and neonatal hair analyses.
Pregnant women (n= 750) will be recruited in midgestation from the Outpatient Prenatal Clinic of the Bulacan Provincial Hospital (BPH). Their blood and hair will be obtained at the time of recruitment and at delivery. Meconium, cord blood, and neonatal hair also will be obtained at delivery. The samples will be analyzed by atomic absorption spectrometry for lead, mercury, cadmium, and gas chromatography/mass spectrometry for the following pesticides and their metabolites: propoxur, diazinon, transfluthrin, malathion, dichlorodiphenyltrichloroethane (DDT), chlorpyrifos, bioallethrin, pretilachlor, lindane, cyfluthrin, and cypermethrin.
Progress Summary:
The enrollment of pregnant women from the prenatal clinic of the BPH was started on April 1, 2002. Within the period of this report, a total of 327 pregnant women have been antenatally enrolled, and maternal blood and hair were obtained and saved. The subjects were subsequently visited in their homes (at least 3 times) to check on the condition of their pregnancy and to remind the mothers that delivery at the BPH was necessary for them (and their infants) to be included in the study. To date, 210 (64 percent) women have given birth to 214 infants: 173 (81 percent) infants were included in the study and 41 were excluded because of incomplete or no specimens drawn at birth either because they were born elsewhere (n= 24) or died soon after birth (n= 17). Among infants who died, partial specimens (meconium, cord blood, or hair) were obtained if feasible. Despite our efforts during the home visits to remind the pregnant women to deliver at BPH, 19 percent still delivered at home or elsewhere either because of imminent delivery or financial problems associated with the cost of hospitalization. The availability of a home telephone was an exception in our study population. Only 9.1 percent had landline phones, although 40.6 percent had access to a cellular phone. Thus, a number of women who delivered elsewhere either forgot to or could not inform us of their deliveries. However, we were adequately forewarned in eight deliveries outside of BPH, and we were able to obtain all the specimens from the mother and infant for their inclusion in the study.
Improvement and Validation of Analytical Methods for Various Pesticides. In the original research proposal, the analysis of blood and hair for 11 parent pesticides and their metabolites only made reference to analytical methods in the literature. To date, we have performed and validated all of these procedures in our laboratory. High recovery rates and precision were obtained for each technique, and limits of detection were established. Comparisons also were made between solid phase extraction and liquid-liquid extraction to determine which method was best suited for each matrix analyzed (cord blood, hair, and meconium). Liquid-liquid extraction was found to be the best method for recovery of both parent pesticide and metabolites in the various matrices, except for the analysis of parent pesticides in meconium. Specific improvements over existing methods also included improving the sensitivity of both parent and metabolite analysis by using calibrators with lower concentrations than previously utilized. The sensitivity of the analysis for pesticide metabolite was further improved by lowering the concentration of the internal standard (2-phenoxybenzoic acid). Analysis of 3,5,6 trichloropyridinol was facilitated by capping the tubes during derivitization, and the use of a quadratic rather than linear calibration curve greatly increased the limit of detection for the compound.
Analysis of Samples for Pesticides and Heavy Metals. The analysis of maternal hair, maternal blood, cord blood, and meconium for parent pesticides and metabolites are ongoing. So far, parent pesticides have been found in maternal hair and meconium, but not in maternal or cord blood. Pesticides found in maternal hair A (collected on initial enrollment) included bioallethrin (19.2 percent), propoxur (17.2 percent), malathion (6 percent), chlorpyrifos (0.7 percent), pretilachlor (0.7 percent), and cyfluthrin (0.7 percent). Maternal hair B samples (collected at delivery) also were positive but had fewer pesticides compared to maternal hair A: 3.6 percent positive for bioallethrin, 1.8 percent for propoxur, and 0.9 percent each for chlorpyrifos and pretilachlor. This difference may be because of the seasonal use of pesticide or maternal washing of hair just before delivery. In the fetus, meconium showed the highest frequency of positive rate for parent pesticide compared to cord blood. Cypermethrin was the most common pesticide found in meconium (8.4 percent), followed by propoxur (5.6 percent), pretilachlor (4.9 percent), malathion (2.1 percent), DDT (1.4 percent), and bioallethrin (0.7 percent).
There were very few samples that were positive for pesticide metabolites. Cord blood was positive for DDE (10 percent) and 2-isopropoxyphenol (8.7 percent), and maternal blood A was positive only for dichlorodiphenyldicloroethylene (DDE) (3.4 percent). All other matrices were negative for pesticide metabolites. The analysis of infant hair for parent pesticides and their metabolites currently is underway.
The samples also were analyzed for heavy metals: cadmium (Cd), lead (Pb), and mercury (Hg). No detectable levels of Cd, Pb, and Hg were found in maternal blood, cord blood, and meconium. On the other hand, for maternal hair A, 21 (9 percent) were positive for Pb (mean concentration of 27.254 ± 53.458 µg/mL) and 66 (48.9 percent) were positive for Hg (mean concentration of 0.468 ± 0.696 µg/mL). Similarly, out of 50 maternal hair B samples taken at delivery (maternal hair B), 12 (24 percent) were positive for Pb (mean concentration of 17.43 ± 9.3 µg/mL ) and 17 (34 percent) were positive for Hg (mean concentration of 0.407 ± 0.734 µg/mL).
Significance. Based on the preliminary results from this report, maternal exposure to pesticides is best detected by analysis of maternal hair. However, there is a striking difference in the positive rate of pesticides in maternal hair obtained antenatally compared to during delivery. Whether this is an effect of seasonal use and exposure to pesticides or washing of maternal hair prior to delivery will need further study. So far, no pesticide metabolite has been detected in maternal hair. This probably implies that the pesticides found in maternal hair may be because of more passive than active maternal exposure to pesticides in the environment.
As far as fetal exposure to pesticides is concerned, meconium seems to be the best matrix to analyze. However, although a number of parent pesticides have been found in meconium, their metabolites were not detected. Whether this indicates poor metabolism of pesticides in the fetus remains to be ascertained.
With regard to heavy metal exposure, only maternal hair analysis yielded a positive result. Maternal hair obtained antenatally and at delivery showed, however, essentially similar positive rates and concentrations of heavy metals, which was not what was observed with pesticides. This may imply uniform exposure to the heavy metals throughout pregnancy. High lead exposure (through maternal hair analysis) was observed in a small cohort of women who resided in an area where a lead battery recycling plant is located. More subjects are being recruited from this area.
Relationship to the Goals of the Study. The preliminary results of the study begin to provide evidence as to which matrix seems to be more reliable for the detection of exposure in the mother and fetus to pesticides and heavy metals in the environment. Analysis of more samples hopefully will validate these preliminary observations further.
Relevance to Protection of the Environment and Human. We hope that with better and more accurate detection of maternal or fetal exposure to environmental toxins, we may be able to intervene early in the prevention of further exposure and potential harm of environmental toxicants on the pregnant woman and her fetus.
Future Activities:
Future activities are to continue the enrollment of the projected 750 subjects in the study. We will increase, by 20 percent, the number of pregnant women initially recruited for the study to compensate for the dropouts at delivery. This is easily done in the study site because of the high population of pregnant women in the outpatient clinic. We also have started recruitment of subjects from areas with high mercury or lead pollution to obtain subjects with potentially heavy exposure to these heavy metals. This will enable us to achieve a population with high, moderate, and low exposure to environmental toxicants.
Journal Articles:
No journal articles submitted with this report: View all 20 publications for this projectSupplemental Keywords:
media, ambient air, atmosphere, drinking water, groundwater, land, soil, indoor air, precipitation, exposure, risk, risk assessment, health effects, human heath, metabolism, vulnerability, dose-response, teratogen, infants, pregnant women, genetic predisposition, susceptibility, cumulative effects, chemicals, toxicants, heavy metals, pesticides, pesticide metabolites, public policy, decisionmaking, community based survey, environmental chemistry, epidemiology, monitoring, analytical, measurement methods, Southeast Asia., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Health Risk Assessment, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Disease & Cumulative Effects, Physical Processes, Children's Health, genetic susceptability, Biology, pesticide exposure, diagnostic tool, fetal exposure, infants, detection, cord blood, pesticides, exposure, children, fetus, Human Health Risk Assessment, meconcium, human exposure, meconium analysis, environmental toxicant, detecting fecal matter, pregnant women, pregnancy, toxicants, exposure assessment, maternal exposure, heavy metals, neonatal hairProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.