Influence of Agrochemicals on Micronutrient Availability and Health Implications Among Small-Scale Farmers in Kellem Wellega Zone

Abstract

Background: Micronutrients are crucial for the growth and development of plants, animals, and humans. In Western Ethiopia, small-scale farmers rely on local soil and food sources for their livelihood. Agricultural practices significantly influence soil microbial populations and physicochemical properties, which are essential for crop growth and quality. Additionally, the presence of agricultural pesticide residues can cause adverse health effects. Objectives: This study aims to assess soil properties and nutrient dynamics of cereals, legumes, and tubers in small-scale farms in Western Ethiopia. It investigates the impact of different agrochemical applications on soil microbial dynamics, physicochemical properties, and the yield and proximate properties of maize. Additionally, the study assesses the prevalence of pesticide use and its occupational exposure among small-scale farmers in the Kellem Wellega Zone. Finally, it evaluates the level of pesticides in the blood of small-scale farmers and associated risk factors. Methods: Samples of various agricultural products, including cereals, legumes, and tubers were collected from small-scale farmers. Soil samples were randomly collected from selected sub-sites and analyzed using standardized procedures, measuring soil pH, electrical conductivity, moisture, organic matter, and ash content. Microbial analysis involved serial dilution and plating techniques, while mineral content (Mn, Zn, Fe, and Cu) was determined through acid digestion and atomic absorption spectrophotometry. Statistical analyses included chi-square, ANOVA, and graphical representation. Additionally, a cross-sectional study design using a structured questionnaire collected data from small-scale farmers' households via face-to-face interviews to assess pesticide use prevalence. Statistical analysis included descriptive statistics, chi-square test, and binary logistic regression (p < 0.05 at 95%CI). Furthermore, blood samples from exposed and non-exposed small-scale farmers using gas-liquid chromatography with an electron capture detector (GC-ECD). Logistic regression models defined relationships between outcomes and explanatory variables. Results: Soil samples had low levels of Mn, Zn, Fe, and Cu, with percentages of 41.7, 61.7, 66.7, and 63.3 mg/kg, respectively. A decrease in pH value was observed in 76.7% of the soil samples. Total mesophilic bacteria levels were below 105 cfu/g in 23.3% of samples, and fungus levels were x below 104 cfu/g in 53.3%. Only 3.3% of organic matter was beneficial, while 86.7% of ash content was unwanted. One-way ANOVA showed significant differences in moisture, ash contents, organic matter, Zn, Fe, and Mn (p < 0.05). Food samples also showed significant differences in crude protein, fats, and fibers (p < 0.05). The highest total mesophilic bacterial count was in compost-treated pots (G), while the lowest was in pots with macronutrient fertilizers and glyphosates (B). Similar trends were observed for total mesophilic fungal counts. Pots with macronutrient fertilizers and glyphosate had the lowest Fe, Zn, Mn, and Cu levels. Compost-treated maize had the highest levels of Fe, Cu, and Zn, while macronutrient fertilizer combined with glyphosate resulted in the lowest micronutrient content. The prevalence of pesticide use was 87.15%. Poor knowledge, practice, and negative attitudes towards pesticide use were observed in 44.2%, 40.2%, and 43.8% of participants, respectively. Farmers directly involved in farming were 2.2 times more likely to be exposed to pesticides (AOR=2.2; 95%CI: 1.12-4.3). Good knowledge reduced exposure likelihood by 58% (AOR = 0.42; 95%CI: 0.24-0.76). Poor practice increased exposure likelihood by 1.84 times (AOR=1.84; 95%CI: 1.05-3.24). Non-symptomatic farmers were 56% less likely to be exposed compared to those showing symptoms of coughing (AOR=0.44; 95%CI: 0.25-0.79). p,p'-DDT, heptachlor, and deltamethrin were frequently detected in blood samples. Exposed farmers had higher mean concentrations of permethrin and p,p'-DDT. Farmers under 40 were 21% less likely to be exposed to permethrin (AOR, 0.21; 95% CI: 0.1-0.44). Male farmers were 17 times more likely to be exposed to heptachlor (AOR, 17.36; 95%CI: 7.34-41.09). Inappropriate PPE use increased exposure to cypermethrin and p,p'-DDE. Conclusions: The study highlights significant deficiencies in micronutrient levels in soil and crops, the impact of agrochemicals on soil and crop quality, and the prevalence of pesticide use and its health risks among small-scale farmers. These findings underscore the need for improved agricultural practices, better education on pesticide use, and appropriate safety measures to protect farmers' health and ensure adequate micronutrient availability in the local agricultural ecosystem.