DNA variants and organophosphate neurotoxicity among emerging farmers in the Western Cape of South Africa.

BACKGROUND: Previous epidemiological studies investigating modification of organophosphate (OP) neurotoxicity by xenobiotic metabolizing enzymes (XMEs) polymorphisms have produced inconsistent results. METHODS: A cross-sectional study of 301 emerging farmers was conducted. Neurotoxicity testing included forward and backward recall, digit span, and vibration sensitivity testing. Questionnaire data included demography, potential confounders, and work history of pesticide exposures. Genomic DNA was analyzed from study participants for DNA variants of two glutathione S-transferases (GSTM1 and GSTT1), N-acetyltransferase 2 (NAT2), and Paraoxonase 1 (PON1). RESULTS: There was evidence of OP pesticide neurotoxicity modification by rs1799931 (NAT2), rs662 (PON1), and the null allele of GSTM1 in multivariate analysis. The strongest evidence of modification was observed for rs1799931 (NAT2) on the relationship between pesticide poisoning and impaired vibration sense. CONCLUSIONS: DNA variants of NAT2, PON1, and GSTM1 may modify OP neurotoxicity, and this requires further exploration.

Organophosphate pesticide exposure as a risk factor for attempted suicide in Cape Town, South Africa: A case-control study.

Pesticides are a commonly used agent for suicide in many Low- and Middle-Income countries (LMICs). However, accumulating evidence suggests that exposure to organophosphate (OP) pesticide may also increase the risk of suicide. We conducted a hospital-based case-control study to investigate whether prior household, garden or occupational OP exposure were associated with attempted suicide using conditional logistic regression modeling. Participants who attempted suicide with any means and were admitted to two Western Cape Province hospitals in South Africa were compared to a sample of controls matched by age, sex and time of admission with unrelated conditions, between August 2015 and August 2017. The means of attempted suicide was not recorded. OP exposure was determined by dialkyl phosphate (DAP) metabolites detected in hair and by environmental and occupational history. Approximately 85% of participants reported using pesticides in the home or garden and 15% of participants reported current or past occupational exposure while working on a farm. Attempted suicide was not associated with reported home or garden OP use (Odds ratio [OR] = 0.59, 95%CI 0.33-1.04), hair DAP metabolites (OR = 1.00, 95%CI 0.98-1.02) or current or past agricultural work (OR = 1.08, 95%CI 0.62-1.87), but was associated with hazardous drinking and unemployment with no household income. We found no evidence that attempted suicide was associated with environmental or occupational pesticide use in an urban South African population attending an emergency center.

Healthcare Utilization 12 Months Prior to Fatal and Non-fatal Suicidal Behaviour in Cape Town, South Africa.

The purpose of this study was to characterize healthcare use for general care and mental health one year before suicidal behavior among individuals with fatal and non-fatal suicidal behavior (NFSB) in Cape Town, South Africa. We linked electronic health records of 484 participants from a case series of 93 completed suicides on whom forensic autopsies were performed at a mortuary in Cape Town, between August 2014 and January 2016; and 391 patients admitted to hospital following NFSB between June 2014 and March 2015, and between August 2015 and August 2017. Time from last healthcare visit to date of suicidal behavior (fatal or non-fatal) was calculated, and Kaplan Meier curves were used to compare the differences by psychiatric diagnoses and study group. Overall, 64.5% of completed suicides and 65.9% of NFSB patients sought general healthcare in the year before suicidal behavior. Most of these visits occurred at hospital outpatient clinics (40.8%) and primary healthcare facilities (31.3%). The prevalence of preexisting psychiatric diagnoses and the use of mental healthcare services was lower for individuals who completed suicide compared to NFSB patients. Common reasons for a healthcare visit among individuals who completed suicide were chronic disease and assault; and psychiatric illness (depression, bipolar, and/or substance use disorders), chronic disease and HIV among NFSB patients. A large proportion of individuals with fatal and NFSB interacted with the healthcare system before suicidal behavior. These findings suggest opportunities for suicide prevention at primary healthcare facilities, antiretroviral treatment centers and emergency departments.HIGHLIGHTSHealthcare access is common among individuals with fatal and NFSB in the year before suicidal behavior.The prevalence of mental disorder diagnoses is higher among NFSB patients than among individuals who completed suicide.A greater proportion of NFSB patients accessed mental healthcare services compared to individuals who completed suicide.

Pesticide Research on Environmental and Human Exposure and Risks in Sub-Saharan Africa: A Systematic Literature Review.

On the African continent, ongoing agriculture intensification is accompanied by the increasing use of pesticides, associated with environmental and public health concerns. Using a systematic literature review, we aimed to map current geographical research hotspots and gaps around environmental and public health risks research of agriculture pesticides in Sub-Saharan Africa (SSA). Studies were included that collected primary data on past and current-used agricultural pesticides and assessed their environmental occurrence, related knowledge, attitude and practice, human exposure, and environmental or public health risks between 2006 and 2021. We identified 391 articles covering 469 study sites in 37 countries in SSA. Five geographical research hotspots were identified: two in South Africa, two in East Africa, and one in West Africa. Despite its ban for agricultural use, organochlorine was the most studied pesticide group (60%; 86% of studies included DDT). Current-used pesticides in agriculture were studied in 54% of the study sites (including insecticides (92%), herbicides (44%), and fungicides (35%)). Environmental samples were collected in 67% of the studies (e.g., water, aquatic species, sediment, agricultural produce, and air). In 38% of the studies, human subjects were investigated. Only few studies had a longitudinal design or assessed pesticide's environmental risks; human biomarkers; dose-response in human subjects, including children and women; and interventions to reduce pesticide exposure. We established a research database that can help stakeholders to address research gaps, foster research collaboration between environmental and health dimensions, and work towards sustainable and safe agriculture systems in SSA.