Occupational exposure to Organophosphate Pesticides and its Effects on Human Sperm Parameters: A systematic Review

Background Previous research has indicated there is a decrease in sperm quality in the last 40 years. There have been a few reports that have associated occupational exposure to Organophosphate pesticides with a decrease in sperm count, abnormalities in the head or tail, and motility leading to infertility over time. Organophosphates are the most common pesticides used in the United States and have been classified as toxic to bees, wildlife, and humans by the EPA even at low exposures. Furthermore, Organophosphates are considered endocrine disrupting chemicals altering the normal function of the endocrine system. This occurs by interfering with the natural hormones the body produces due to their strong bind to estrogen and androgen receptors. Objective This systematic review sought to identify relevant studies evaluating the relationship of occupational exposure to Organophosphate pesticides and the decrease of sperm parameters in agriculture workers, pesticide sprayers, and farm workers worldwide. Methods PubMed, Scopus, Himmelfarb, and Agriculture Environmental Science databases were searched for all studies in English. Peer-reviewed articles were selected between the years of 2008 and 2016. Risk of bias was assessed according to the Navigation Guide a Systematic Review Methodology. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was utilized to rate the quality of evidence of each study. Results Five studies were identified, reviewed, and analyzed according to inclusion criteria. Selected studies were rated “low, probably low, not applicable, probably high risk, and high risk” for risk of bias. Studies were assigned a “low quality” rating for strength of evidence. Grey literature was excluded. Conclusion There is sufficient evidence that supports a positive association between occupational Organophosphate exposure and a decrease of sperm parameters in agriculture workers, pesticide sprayers, and farm workers worldwide. Sperm analysis demonstrated a decrease in sperm volume, motility, quality of sperm, and DNA damage, however, future studies are needed to explore this association further

Fall Safety Assessment at the New School of Public Health and Health Services Building

Objective: Falls are one of the leading causes of workplace death, lost work time, and costs to industry, particularly in construction. The public health burden of falls is significant, as approximately 25% of nonfatal injuries and 38% of fatalities in the general construction industry are due to falls. The goal of this study is to develop an assessment tool to evaluate fall safety in general construction and to evaluate fall safety among five skilled construction trades (i.e. electricians, painters, carpenters, welders, and roofers) throughout different stages of a new building construction project. The project is the new School of Public Health and Health Services building at The George Washington University at Washington Circle in Foggy Bottom, Washington, DC, being built by the general contractor The Whiting-Turner Contracting Company. Methods: A comprehensive assessment instrument was developed through review of pre-existing assessment tools and modified according to Occupational Safety and Health Administration (OSHA) standards for general construction, validated through inter-rater reliability by a panel of experts (including the on-site safety superintendent), and tested for on-site usability through a two-week pilot study. Data were collected using the GW Audit of Fall Risk (GAFR) instrument by a master\u27s-level researcher through routine observation of the construction site throughout the five construction phases (i.e. concrete pouring, skin, interior rough end, interior finishes, and roofing). Results: Collected data are organized in the GAFR assessment instrument into eight domains: general safety, guardrails, personal fall arrest, safety net system, roof sheathing, scaffolding, aerial lifts, and ladders. Observations are scored dichotomously as to whether or not it was observed, and if observed, whether or not it meets the definition of best safety practice (as noted in OSHA regulations). Though the study is still ongoing, the current collected data presents statistics on the prevalence of fall hazards, and the frequency of fall safety compliances for each of the five trades by construction phase. Conclusions: Fall hazards in skilled trades have been understudied. This unique university-general contractor partnership capitalizes on the opportunity to ensure public health principles are being realized during construction. This presentation will include the application of the GAFR assessment instrument and the current preliminary results, highlighting the importance of observational assessment of worksites. Additionally, the lessons learned from the field assessments will also be discussed

Aneuploidy: a common and early evidence-based biomarker for carcinogens and reproductive toxicants.

Aneuploidy, defined as structural and numerical aberrations of chromosomes, continues to draw attention as an informative effect biomarker for carcinogens and male reproductive toxicants. It has been well documented that aneuploidy is a hallmark of cancer. Aneuploidies in oocytes and spermatozoa contribute to infertility, pregnancy loss and a number of congenital abnormalities, and sperm aneuploidy is associated with testicular cancer. It is striking that several carcinogens induce aneuploidy in somatic cells, and also adversely affect the chromosome compliment of germ cells. In this paper we review 1) the contributions of aneuploidy to cancer, infertility, and developmental abnormalities; 2) techniques for assessing aneuploidy in precancerous and malignant lesions and in sperm; and 3) the utility of aneuploidy as a biomarker for integrated chemical assessments of carcinogenicity, and reproductive and developmental toxicity

Using Physiologically-Based Pharmacokinetic Models to Incorporate Chemical and Non-Chemical Stressors into Cumulative Risk Assessment: A Case Study of Pesticide Exposures

Cumulative risk assessment has been proposed as an approach to evaluate the health risks associated with simultaneous exposure to multiple chemical and non-chemical stressors. Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models can allow for the inclusion and evaluation of multiple stressors, including non-chemical stressors, but studies have not leveraged PBPK/PD models to jointly consider these disparate exposures in a cumulative risk context. In this study, we focused on exposures to organophosphate (OP) pesticides for children in urban low-income environments, where these children would be simultaneously exposed to other pesticides (including pyrethroids) and non-chemical stressors that may modify the effects of these exposures (including diet). We developed a methodological framework to evaluate chemical and non-chemical stressor impacts on OPs, utilizing an existing PBPK/PD model for chlorpyrifos. We evaluated population-specific stressors that would influence OP doses or acetylcholinesterase (AChE) inhibition, the relevant PD outcome. We incorporated the impact of simultaneous exposure to pyrethroids and dietary factors on OP dose through the compartments of metabolism and PD outcome within the PBPK model, and simulated combinations of stressors across multiple exposure ranges and potential body weights. Our analyses demonstrated that both chemical and non-chemical stressors can influence the health implications of OP exposures, with up to 5-fold variability in AChE inhibition across combinations of stressor values for a given OP dose. We demonstrate an approach for modeling OP risks in the presence of other population-specific environmental stressors, providing insight about co-exposures and variability factors that most impact OP health risks and contribute to children’s cumulative health risk from pesticides. More generally, this framework can be used to inform cumulative risk assessment for any compound impacted by chemical and non-chemical stressors through metabolism or PD outcomes

Determinants of Childhood Zoonotic Enteric Infections in a Semirural Community of Quito, Ecuador.

Domestic animals in the household environment have the potential to affect a child's carriage of zoonotic enteric pathogens and risk of diarrhea. This study examines the risk factors associated with pediatric diarrhea and carriage of zoonotic enteric pathogens among children living in communities where smallholder livestock production is prevalent. We conducted an observational study of children younger than 5 years that included the analysis of child (n = 306) and animal (n = 480) fecal samples for Campylobacter spp., atypical enteropathogenic Escherichia coli, Shiga toxin-producing E. coli, Salmonella spp., Yersinia spp., Cryptosporidium parvum, and Giardia lamblia. Among these seven pathogens, Giardia was the most commonly identified pathogen among children and animals in the same household, most of which was found in child-dog pairs. Campylobacter spp. was also relatively common within households, particularly among child-chicken and child-guinea pig pairs. We used multivariable Poisson regression models to assess risk factors associated with a child being positive for at least one zoonotic enteric pathogen or having diarrhea during the last week. Children who interacted with domestic animals-a behavior reported by nearly three-quarters of households owning animals-were at an increased risk of colonization with at least one zoonotic enteric pathogen (prevalence ratio [PR] = 1.56, 95% CI: 1.00-2.42). The risk of diarrhea in the last seven days was elevated but not statistically significant (PR = 2.27, CI: 0.91, 5.67). Interventions that aim to reduce pediatric exposures to enteric pathogens will likely need to be incorporated with approaches that remove animal fecal contamination from the domestic environment and encourage behavior change aimed at reducing children's contact with animal feces through diverse exposure pathways

Post-transcriptional regulation of satellite cell quiescence by TTP-mediated mRNA decay.

Skeletal muscle satellite cells in their niche are quiescent and upon muscle injury, exit quiescence, proliferate to repair muscle tissue, and self-renew to replenish the satellite cell population. To understand the mechanisms involved in maintaining satellite cell quiescence, we identified gene transcripts that were differentially expressed during satellite cell activation following muscle injury. Transcripts encoding RNA binding proteins were among the most significantly changed and included the mRNA decay factor Tristetraprolin. Tristetraprolin promotes the decay of MyoD mRNA, which encodes a transcriptional regulator of myogenic commitment, via binding to the MyoD mRNA 3' untranslated region. Upon satellite cell activation, p38α/β MAPK phosphorylates MAPKAP2 and inactivates Tristetraprolin, stabilizing MyoD mRNA. Satellite cell specific knockdown of Tristetraprolin precociously activates satellite cells in vivo, enabling MyoD accumulation, differentiation and cell fusion into myofibers. Regulation of mRNAs by Tristetraprolin appears to function as one of several critical post-transcriptional regulatory mechanisms controlling satellite cell homeostasis

Environmental exposure to polychlorinated biphenyls and p,p\u27-DDE and sperm sex-chromosome disomy

Background: Chromosomal abnormalities contribute substantially to reproductive problems, but the role of environmental risk factors has received little attention. Objectives: We evaluated the association of polychlorinated biphenyl (PCB) and dichlorodiphenyldichloroethylene (p,p´-DDE) exposures with sperm sex-chromosome disomy. Methods: We conducted a cross-sectional study of 192 men from subfertile couples. We used multiprobe fluorescence in situ hybridization (FISH) for chromosomes X, Y, and 18 to determine XX, YY, XY, and total sex-chromosome disomy in sperm nuclei. Serum was analyzed for concentrations of 57 PCB congeners and p,p´-DDE. Poisson regression models were used to calculate incidence rate ratios (IRRs) for disomy by exposure quartiles, controlling for demographic characteristics and semen parameters. Results: The median percent disomy was 0.3 for XX and YY, 0.9 for XY, and 1.6 for total sex-chromosome disomy. We observed a significant trend of increasing IRRs for increasing quartiles of p,p´-DDE in XX, XY, and total sex-chromosome disomy, and a significant trend of increasing IRRs for increasing quartiles of PCBs for XY and total sex-chromosome disomy; however, there was a significant inverse association for XX disomy. Conclusions: Our findings suggest that exposure to p,p´-DDE may be associated with increased rates of XX, XY, and total sex-chromosome disomy, whereas exposure to PCBs may be associated with increased rates of YY, XY, and total sex-chromosome disomy. In addition, we observed an inverse association between increased exposure to PCBs and XX disomy. Further work is needed to confirm these findings

Staphylococcus aureus Nasal Carriage among Beefpacking Workers in a Midwestern United States Slaughterhouse

Occupational contact with livestock is an established risk factor for exposure to livestock-associated methicillin-resistant Staphylococcus aureus (MRSA), particularly among industrial swine workers. While S. aureus is known to infect cattle, livestock-associated S. aureuscarriage among workers in the beef production chain has received limited attention. Beefpacking workers, who slaughter, butcher and process cattle, have intensified exposure to potentially infectious animal materials and may be at risk of livestock-associated S. aureusexposure. We conducted a cross-sectional study of beefpacking workers (n = 137) at an industrial slaughterhouse in the Midwestern United States to evaluate prevalence and characteristics of S. aureus nasal colonization, specifically the absence of the scn gene to identify putative association with livestock, antibiotic susceptibility, presence of Panton-Valentin leukocidin (PVL) genes lukS-PV and lukF-PV, and spa type. Overall prevalence of S.aureus nasal carriage was 27.0%. No workers carried livestock-associated MRSA. Methicillin-sensitive S. aureus isolates (MSSA) recovered from five workers (3.6%) lacked the scn gene and were considered putative livestock-associated S. aureus (pLA-SA). Among pLA-SA isolates, spa types t338, t748, t1476 and t2379 were identified. To our knowledge, these spatypes have not previously been identified as associated with livestock. Prevalence of human-adapted MRSA carriage in workers was 3.6%. MRSA isolates were identified as spa types t002, t008 and t024, and four of five MRSA isolates were PVL-positive. To date, this is the first study to indicate that industrial beefpacking workers in the United States may be exposed to livestock-associated S. aureus, notably MSSA, and to spa types not previously identified in livestock and livestock workers. Occupational exposure to livestock-associated S. aureus in the beef production chain requires further epidemiologic investigation