Immune response cytokines as potential biomarkers for DDT induced neurodegeneration

Background: The world incidence rate of Alzheimer's Disease (AD) is 64 cases per 1,000 individuals. Due to the aging population, the prevalence of AD is however increasing and yet, little remains known about the etiology of AD. Objective: Previous studies suggested relationships between AD, neuro-inflammation and organochloride pesticide exposures, therefore, we aimed to study the association between DDT and possible biomarkers of AD. Materials and Methods: We explored literature on inflammation, pesticide exposure and biomarkers associated with AD. We measured eligible markers in adult C57BL/6J mice treated with DDT for 4 months (dose=3 mg/kg/day); Hippocampi tissue gene expression was quantified by qPCR. IL-1ß expression was compared in test vs. control mice using t-tests. Furthermore, we studied population data to: explore the immunological markers, identify gaps and possible approaches for addressing them. Results: Average serum levels of IL-1ß were significantly higher (p<0.05) in the DDT treated mice compared to controls. IL-1ß stimulates APP and Aß41 syntheses, which may be associated with AD pathogenesis. Gaps identified included: (1) Parallel analysis of genetic and environmental risk factors; (2) Definition of toxin-induced neuro-inflammation focusing on microglial physiology. Studies focusing on the physiological effects of DDT, focusing on epigenetic aberrations may aid in the description of the effect of DDT on gene expression; (3) The blood-brain-barrier limits comparisons between peripheral and brain-localized IL-1ß and DDT concentrations, suggesting the need for robust measurement schemes. We report that there is still much uncertainty regarding biomarkers associated with AD pathogenesis. Conclusions: Currently, we cannot confidently report that DDT has a causal role in AD incidence. However, by first quantifying the cytokine concentrations post-exposure to DDT, by measuring the metabolite DDE, we can further explore potential drifts in immune marker concentrations that could provide a platform for future studies.

Salivary cotinine levels as a biomarker for green tobacco sickness in dry tobacco production among Thai traditional tobacco farmers.

BACKGROUND: Dry Thai traditional tobacco (Nicotiana Tabacum L.) production involves a unique process: (a) picking tobacco leaves, (b) curing tobacco leaves, (c) removing stems of tobacco leaves, cutting leaves and putting on a bamboo rack, (d) drying in the sun, reversing a rack, spraying a tobacco extract to adjust the tobacco's color, storing dried tobacco and packaging. These processes may lead to adverse health effects caused by dermal absorption of nicotine such as Green Tobacco Sickness (GTS). OBJECTIVES: The aim of this study was to determine the correlation between GTS resulting from dry Thai traditional tobacco production and salivary cotinine levels among Thai traditional tobacco farmers in Nan Province, Thailand. MATERIALS AND METHODS: A prospective cohort study was conducted with 20 tobacco farmers and 20 non-tobacco farmers in Praputtabath Sub-District and Phatow Sub-District. The participants were randomly selected and interviewed using in person questionnaires with bi-weekly follow-up for 14 weeks. During each contact, the cotinine concentration was measured by NicAlert(TM) Saliva strip tests (NCTS). Descriptive statistics and Spearman's correlation (Spearman's rho) was used to examine the relationship between the variables at both 0.01 and 0.05 significant probability levels. RESULTS: This study indicated that GTS from dry tobacco production has the potential to be considered a common occupational disease. This study demonstrated the usefulness of salivary cotinine level measurements by NCTS. The levels were well correlated with farmers who were employed in the dry Thai tobacco production industry. Salivary cotinine levels were also significantly correlated with the prevalence of GTS in the group of tobacco farmers at any given time within a crop season. However, the production process of dry Thai traditional tobacco is different from that evaluated in our previous studies where GTS and salivary cotinine level were correlated in workers working in humid conditions. CONCLUSIONS: The long-term effects of such exposure should be investigated and health education programs with health risk exposure studies to increase awareness amongst farmers is recommended.

Organophosphate pesticide exposure and dialkyl phosphate urinary metabolites among chili farmers in northeastern Thailand.

BACKGROUND: Chlorpyrifos and profenofos are organophosphate pesticides (OPPs), we studied exposure and urinary metabolites in an agricultural area in the northeastern of Thailand during the chili-growing season (March - April) in 2012. OBJECTIVE: This study was designed to assess pesticide exposure concentration through dermal and inhalation pathways and to find and depict a relationship between urinary metabolites and means of exposure. MATERIALS AND METHODS: To estimate the pesticides exposure concentration, dermal wipes (hand, face, and feet), dermal patches and air samples were collected from 38 chili farmers. The morning void of pre and post application urine samples was an indicator of biological monitoring in the study which derived from 39 chili farmers. RESULTS: Chlorpyrifos and profenofos residues were detected on dermal patches, face wipes, and hand wipe samples, while no significant residues were found on the feet. Using a personal air sampling technique, all air samples detected pesticide residues. However, significant correlation between dermal pesticide exposure concentration and inhalation was not found (p>0.05). For urinary metabolite levels, there was a relationship between the first pre application morning void and post application morning void (p < 0.05); similar to the association between the first pre application morning void and the second post application morning void (p < 0.05). The main relationship between pesticide exposure and urinary metabolite was found to have been relevant to dermal exposure (r= 0.405; p < 0.05). CONCLUSIONS: The results of this study could suggested that public health education training programs, including the use of appropriate personal protective equipment (PPE), should be offered for the chili growing farmers in order to improve their ability to properly use pesticides. KEY WORDS: pesticide exposure, chili farmers, urinary metabolites, organophosphate pesticides.

Health risk assessment related to dermal exposure of chlorpyrifos: a case study of rice growing farmers in Nakhon Nayok Province, Central Thailand.

To date, pesticides, especially organophosphate pesticide such as chlorpyrifos, have been frequently applied to paddy fields over time to maintain product quality, protect agricultural crops from various pests, and increase yield. This study evaluates dermal exposure to chlorpyrifos in rice farmers along with providing a health risk assessment. Thirty-five rice farmers participated and completed an in-person interview, and patch technique was used to evaluate dermal exposure to chlorpyrifos. The chlorpyrifos residue was extracted from the gauze patches and quantified by gas chromatography equipped with flame photometric detector (GC-FPD). The results showed that chlorpyrifos concentrations were greater in males (526.34 ± 478.84 mg/kg) than females (500.75 ± 595.15 mg/kg). Average daily dose sampled from seven points on male and female farmers were 31.72 × 10(-4), 193.32 × 10(-4), 5.38 × 10(-4), 190.48 × 10(-4), 170.47 × 10(-4), 465.91 × 10(-4), and 43.04 × 10(-4) mg/kg-day. The hazard quotient (HQ) at the mean and 95th percentile level was found to be greater than acceptable (HQ > 1). Rice-growing farmers in this area may be at risk for adverse health effects due to continuous dermal exposure to chlorpyrifos from their improper use of personal protective equipment (PPE).