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theses

This study's main objective was to develop and validate novel pyrethroid exposure biomarkers and assess novel aspects of pyrethroid exposure characterization. This was achieved by 1) developing and applying a sensitive method to measure six pyrethroid metabolites in umbilical cord serum, 2) developing and validating a method to detect six pyrethroid metabolites in saliva of occupationally exposed workers, and 3) comparing performance of two gas chromatography-ion trap mass spectrometry (GCITMS) instruments based on ion source placement. Aim 1 validated a novel method to detect pyrethroid metabolites in cord serum samples. Of the six pyrethroid metabolites analyzed for, five were found in 62 samples analyzed from maternal-fetal dyads from central New Jersey, USA. Non-specific metabolites, 3-phenoxybenzoic acid (3-PBA), trans and cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (t- and c-DCCA), and trans-chrysanthemum dicarboxylic acid (t-CDCA) were found in 32%, 16%, 8% and 8% of samples, respectively, while specific metabolites, 4-fluoro-3-phenoxybenzoic acid (FPBA) and cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (c-DBCA) were detected in 3% and 0% of the samples, respectively. The geometric mean for 3-PBA was 0.11 ng/mL and below limit of detection (<LOD) for the remaining metabolites. Overall, this method was sensitive enough to detect pyrethroid metabolites at biologically relevant concentrations found in umbilical cord serum of exposed maternalfetal dyads.
Aim 2 validated a novel method to extract and analyze six common pyrethroid metabolites in saliva by GC-ITMS. Eighteen saliva and 18 urine samples were collected from nine pest control operators (PCOs) for analysis. Urinary 3PBA concentrations >LOD were found in 100% of the population. 3PBA was present in saliva <LOD in two of three workers who had workday exposures detected in urine (n=3). This novel method was able to detect salivary metabolite concentrations, although they were under the detection limit.
Aim 3 assessed detection and quantification of pyrethroid and pyrethroid metabolite due to differing ionization conditions between two GC-ITMS. Intra- and inter-day variation, as well as differences in mass spectrometric parameters, were compared between two instruments, one fitted with an external ionization source, and the other with an internal source. Fragmentation patterns differed between instruments, where smaller fragments were generated by internal ionization as compared to external. External ionization improved sensitivity and precision for pyrethroids between 2 – 10x. Metabolite sensitivities and precision were either comparable or improved using external ionization, except for c-DBCA. This study emphasizes the importance of ionization source placement in instrument performance when detecting pyrethroid insecticides and their metabolites by GC/ITMS.

http://dissertations.umi.com/gsnb.rutgers:12074

Ph.D.

Includes bibliographical references

doi:10.7282/t3-2r7x-ns57

The author owns the copyright to this work.