Identifying environmental factors that influence immune response to SARS-CoV-2: Systematic evidence map protocol.

BACKGROUND: Widespread environmental contamination can directly interact with human immune system functions. Environmental effects on the immune system may influence human susceptibility to respiratory infections as well as the severity of infectious diseases, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Furthermore, the efficacy of vaccines to respiratory diseases may be impacted by environmental exposures through immune perturbations. Given the quick pace of research about COVID-19 and associated risk factors, it is critical to identify and curate the streams of evidence quickly and effectively. OBJECTIVE: We developed this systematic evidence map protocol to identify and organize existing human and animal literature on high-priority environmental chemical classes (Per- and polyfluoroalkyl substances, pesticides, phthalates, quaternary ammonium compounds, and air pollutants) and their potential to influence three key outcomes: (1) susceptibility to respiratory infection, including SARS-CoV-2 (2) severity of the resultant disease progression, and (3) impact on vaccine efficacy. The result of this project will be an online, interactive database which will show what evidence is currently available between involuntary exposures to select environmental chemicals and immune health effects, data gaps that require further research, and data rich areas that may support further analysis. SEARCH AND STUDY ELIGIBILITY: We will search PubMed for epidemiological or toxicological literature on select toxicants from each of the chemical classes and each of the three outcomes listed above. STUDY APPRAISAL AND SYNTHESIS OF METHODS: For each study, two independent reviewers will conduct title and abstract screening as well as full text review for data extraction of study characteristics. Study quality will not be evaluated in this evidence mapping. The main findings from the systematic evidence map will be visualized using a publicly available and interactive database hosted on Tableau Public.

Pesticide exposure and adverse health effects associated with farmwork in Northern Thailand.

OBJECTIVES: To assess pesticide exposure and understand the resultant health effects of agricultural workers in Northern Thailand. METHODS: This was a cross-sectional study. We quantified exposure to pesticides, including chlorpyrifos, methomyl, and metalaxyl, by air sampling and liquid chromatography/mass spectrometry. We estimated differences in self-reported health outcomes, complete blood counts, cholinesterase activity, and serum/urine calcium and creatinine concentrations at baseline between farmworkers and comparison workers, and after pesticide spraying in farmworkers only. RESULTS: This study included 97 men between the ages of 22 and 76 years; 70 were conventional farmworkers; and 27 did not report any prior farmwork or pesticide spraying. None of the farmworkers wore standardized personal protective equipment (PPE) for the concentrated chemicals they were working with. Methomyl (8.4-13 481.9 ng/m3 ), ethyl chlorpyrifos (11.6-67 759 ng/m3 ), and metalaxyl (13.9-41 191.3 ng/m3 ) were detected via personal air sampling. When it came to reporting confidence in the ability to handle personal problems, only 43% of farmworkers reported feeling confident, which reflects higher stress levels in comparison to 78% of comparison workers (P = .028). Farmworkers also had significantly lower monocyte counts (P = .01), serum calcium (P = .01), red blood count (P = .01), white blood cell count (P = .04), and butyrylcholinesterase activity (P < .0001), relative to comparison workers. After adjusting for body mass index (BMI), age, and smoking, methomyl air concentrations were associated with a decrease in farmworker acetylcholinesterase activity (beta = -0.327, P = .016). CONCLUSIONS: This population of farmworkers had significant alterations in stress measures and clinical biomarkers, including decreased blood cell counts and cholinesterase activity, relative to matched controls. These changes are potentially linked to occupational pesticide exposures. Improving PPE use presents a likely route for preventive intervention in this population.

Environmental exposures, stem cells, and cancer.

An estimated 70-90% of all cancers are linked to exposure to environmental risk factors. In parallel, the number of stem cells in a tissue has been shown to be a strong predictor of risk of developing cancer in that tissue. Tumors themselves are characterized by an acquisition of "stem cell" characteristics, and a growing body of evidence points to tumors themselves being sustained and propagated by a stem cell-like population. Here, we review our understanding of the interplay between environmental exposures, stem cell biology, and cancer. We provide an overview of the role of stem cells in development, tissue homeostasis, and wound repair. We discuss the pathways and mechanisms governing stem cell plasticity and regulation of the stem cell state, and describe experimental methods for assessment of stem cells. We then review the current understanding of how environmental exposures impact stem cell function relevant to carcinogenesis and cancer prevention, with a focus on environmental and occupational exposures to chemical, physical, and biological hazards. We also highlight key areas for future research in this area, including defining whether the biological basis for cancer disparities is related to effects of complex exposure mixtures on stem cell biology.

Psychosocial correlates of smokeless tobacco use among Indiana adolescents.

Adolescent tobacco use is influenced by intrapersonal (e.g., impulse control) and external factors, such as behaviors of friends and peers. The relationships of these factors to smokeless tobacco (ST) use are not yet fully understood. This is especially true as it pertains to the simultaneous examination of psychological and normative perceptions. Using constructs of the Biopsychosocial Model, this study investigates factors associated with lifetime ST use among middle and high school students. Data were analyzed from 938 Indiana middle and high school students. Binary sequential logistic regression was performed to examine the relationship of personal characteristics and psychosocial measures to adolescent lifetime ST use. Approximately 9 % reported having ever used ST, among which 78.6 % were male. Females and younger students were less likely to have used ST in their lifetime, whereas participants with a sibling smoker and those who compared their life to the lives of others were more likely to report lifetime ST usage. In the presence of psychological and normative variables, sex, age, and comparing one's life to others remained significant. Additionally, participants who perceived higher friend approval of substance use were significantly more likely to report lifetime ST use. Understanding the normative perceptions of adolescents may lend insight into the drivers of ST use adolescent subgroups and, which may enable community and school officials to tailor interventions to prevent ST initiation and promote cessation.