Serum PCB levels and congener profiles among US construction workers

Abstract Background The presence of PCB in caulking (sealant) material found in masonry buildings has been well-documented in several countries. A recent investigation of 24 buildings in the greater Boston area found that 8 buildings had high PCB levels in caulking materials used around window frames and in joints between masonry blocks. Workers removing caulking material have been shown to have elevated serum PCB levels. Methods This project compared serum PCB levels among male workers who installed and/or removed PCB-containing caulking material from buildings in the greater Boston area with reference serum PCB levels from 358 men from the same area. Serum PCB levels were measured in the same laboratory by liquid-liquid extraction, column chromatography clean-up and dual capillary column GC/microECD analysis. Results When the congener profiles were compared between the reference population and the construction workers, the serum levels of the more volatile, lighter PCBs (di-, tri-and tetrachloro, sum of IUPAC# 6–74) were substantially higher among the construction workers. One of the youngest workers had the lowest total serum PCB levels (sum of 57 congeners) of all 6 workers, but the contribution of more volatile (less chlorinated) PCB congeners (#16, 26,28,33,74,66, and 60) was markedly higher than in other 5 workers and reference men. Only this worker was working on a job that involved removing PCB caulking at the time of the blood sampling. Conclusion While the results of this pilot study are based upon small numbers (6 construction workers who handled PCB caulking), the serum PCB levels among the construction workers exceed the referents. Comparison of the congener profiles suggests that there are substantial differences between the construction workers and the general population samples. These differences, and the similarities of profiles among the construction workers strongly suggest that occupational contact with caulking material can be a major source of PCB exposure for construction workers.http://deepblue.lib.umich.edu/bitstream/2027.42/117256/1/12940_2007_Article_124.pd

An Unrecognized Source of PCB Contamination in Schools and Other Buildings

An investigation of 24 buildings in the Greater Boston Area revealed that one-third (8 of 24) contained caulking materials with polychlorinated biphenyl (PCB) content exceeding 50 ppm by weight, which is the U.S. Environmental Protection Agency (U.S. EPA) specified limit above which this material is considered to be PCB bulk product waste. These buildings included schools and other public buildings. In a university building where similar levels of PCB were found in caulking material, PCB levels in indoor air ranged from 111 to 393 ng/m(3); and in dust taken from the building ventilation system, < 1 ppm to 81 ppm. In this building, the U.S. EPA mandated requirements for the removal and disposal of the PCB bulk product waste as well as for confirmatory sampling to ensure that the interior and exterior of the building were decontaminated. Although U.S. EPA regulations under the Toxic Substances Control Act stipulate procedures by which PCB-contaminated materials must be handled and disposed, the regulations apparently do not require that materials such as caulking be tested to determine its PCB content. This limited investigation strongly suggests that were this testing done, many buildings would be found to contain high levels of PCBs in the building materials and potentially in the building environment. The presence of PCBs in schools is of particular concern given evidence suggesting that PCBs are developmental toxins

Phase Focusing In Linear-beam Devices.

PhDElectrical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/185430/2/6202767.pd

Pesticide Mixtures and Risks of Human Sperm Aberrations

Background: Endocrine-disrupting chemicals (EDCs) such as organophosphate (OP) and pyrethroid (PYR) pesticides, affect human reproductive health. Investigating “real-life” environmentally relevant concentrations and mixtures of EDCs is important to identify potential interactions between highly correlated environmental exposures and reproductive health outcomes. Objectives: This study investigated the effects of combined environmental exposures to OP and PYR pesticides and their association with the frequency of sperm chromosomal abnormalities (disomy) among adult men. We evaluated the hypothesis that pesticide mixtures, specifically OP and PYR interactions, alter associations of sperm chromosomal abnormalities. Methods: One hundred fifty-nine men originating from a parent study of couples seeking infertility evaluation were evaluated. Fluorescence in situ hybridization was used for chromosomes X, Y, and 18 to determine disomy in sperm nuclei. Urine was analyzed for concentrations of PYR metabolite [3-phenoxybenzoic acid (3PBA)] using high-performance liquid chromatography. Gas chromatography coupled with mass spectrometry was used to analyze urinary concentrations of dialkyl phosphate (DAP) metabolites of OPs. Poisson regression models were used to calculate incidence rate ratios for each disomy type by exposure quartile of OP and PYR pesticides, controlling for potential confounders. Interactions between each DAP metabolite and 3PBA and associations with each disomy outcome were examined. Results: Significant interactions were found between DAP metabolites and 3PBA for all disomy outcomes. Most of the associations showed increased disomy rates, higher than the values previously reported for each individual chemical class, by levels of specific DAP metabolites and 3PBA exposure. Increase in disomy rates occurred mainly between the second and third exposure quartiles and without substantial additional increases between the third and fourth exposure quartile, producing non-linear dose responses. Nonmonotonic patterns were observed in depicted graphs (displaying bell-shaped profiles). Significant inverse and positive parameter estimates were seen across all DAP metabolites by 3PBA quartiles. Conclusions: This study demonstrates the methodological problems posed when evaluating environmental chemical mixtures, particularly when the health outcome is a count that is best suited for non-logistic modeling, such as Poisson regression. Consistent interactions were observed between OP and PYR pesticides, which strengthened the associations seen beyond the main effects of each individual exposure. Methods specific to investigating interactions in Poisson models are needed to determine an optimized approach for evaluating pesticide mixtures (with different EDC modes of action) and their effects on count based outcomes

Final report for theoretical and experimental investigation of large-signal traveling-wave tubes

http://deepblue.lib.umich.edu/bitstream/2027.42/6048/5/bac6312.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/6048/4/bac6312.0001.001.tx

Dialkyl phosphate urinary metabolites and chromosomal abnormalities in human sperm.

BACKGROUND: The past decade has seen numerous human health studies seeking to characterize the impacts of environmental exposures, such as organophosphate (OP) insecticides, on male reproduction. Despite an extensive literature on OP toxicology, many hormone-mediated effects on the testes are not well understood. OBJECTIVES: This study investigated environmental exposures to OPs and their association with the frequency of sperm chromosomal abnormalities (i.e., disomy) among adult men. METHODS: Men (n=159) from a study assessing the impact of environmental exposures on male reproductive health were included in this investigation. Multi-probe fluorescence in situ hybridization (FISH) for chromosomes X, Y, and 18 was used to determine XX18, YY18, XY18 and total disomy in sperm nuclei. Urine was analyzed using gas chromatography coupled with mass spectrometry for concentrations of dialkyl phosphate (DAP) metabolites of OPs [dimethylphosphate (DMP); dimethylthiophosphate (DMTP); dimethyldithiophosphate (DMDTP); diethylphosphate (DEP); diethylthiophosphate (DETP); and diethyldithiophosphate (DEDTP)]. Poisson regression was used to model the association between OP exposures and disomy measures. Incidence rate ratios (IRRs) were calculated for each disomy type by exposure quartiles for most metabolites, controlling for age, race, BMI, smoking, specific gravity, total sperm concentration, motility, and morphology. RESULTS: A significant positive trend was seen for increasing IRRs by exposure quartiles of DMTP, DMDTP, DEP and DETP in XX18, YY18, XY18 and total disomy. A significant inverse association was observed between DMP and total disomy. Findings for total sum of DAP metabolites concealed individual associations as those results differed from the patterns observed for each individual metabolite. Dose-response relationships appeared nonmonotonic, with most of the increase in disomy rates occurring between the second and third exposure quartiles and without additional increases between the third and fourth exposure quartiles. CONCLUSIONS: This is the first epidemiologic study of this size to examine the relationship between environmental OP exposures and human sperm disomy outcomes. Our findings suggest that increased disomy rates were associated with specific DAP metabolites, suggesting that the impacts of OPs on testis function need further characterization in epidemiologic studies