Failure Mode, Effects, and Criticality Analysis (FMECA) of Pesticide Application Equipment and Risk Perception Boundaries Among Vegetable Farmers in Côte d’Ivoire

1. Introduction

In sub-Saharan Africa, the protection of intensive vegetable crops relies heavily on the use of synthetic chemical pesticides, applied via manual knapsack sprayers [1]. While scientific research has extensively focused on active ingredient toxicity and chemical residues on food commodities, the intrinsic physical failures of the application machinery itself remain under-documented [2,3]. Yet, the structural integrity of these tools governs spray spectrum uniformity, directly determining the intensity of both dermal operator exposure and ecotoxicological drift into soil and water bodies [4,5].

By deploying Failure Mode, Effects, and Criticality Analysis (FMECA) a core tool from industrial reliability engineering this article aims to analyze and rank mechanical failures within an active sprayer pool in Côte d’Ivoire, confronting these technological breaking points with market gardeners' empirical cognitive representations of chemical risks [6,7].

2. Materials and Methods

The technical diagnosis focused on a sub-sample of 294 manual knapsack sprayers, distributed across the District of Abidjan (n = 145), the Bouaké region (n = 83), and the Korhogo region (n = 66). Direct mechanical field inspections were carried out to catalog all hydraulic and structural anomalies. The FMECA framework was applied to calculate the Global Criticality Index (C) for each defect as a matrix product: C = O x G x D. Occurrence (O) represents empirical failure frequency; Gravity (G) scores the impact on agronomic dosage precision and human contamination (on a 1–5 scale); and Detectability (D) rates the difficulty of identifying the anomaly before operation (on a 1– 4 scale). Concurrently, individual surveys and focus groups were deployed to measure chemical risk perception thresholds among the applicators.

3. Results

3.1. Identification of Sprayer Physical and Mechanical Anomalies

The mechanical audit reveals a massive structural degradation of chemical application tools currently in use, as detailed in Table 1. Out of 294 rigorously inspected units, 85% (250 sprayers) present at least one major functional defect, with this rate peaking at 88% in the Abidjan area. In total, nine main failure modes alter structural and hydraulic performance. Pumping lever jams stand out as the most recurring defect (211 cases), followed by the loss of the filling filter inside the tank (129 cases) and torn carrying straps (119 cases). Integrity failures, such as unsealable tank caps (111 cases) and tank shell cracks (105 cases), constitute permanent points for chemical mix leakage.

3.2. FMECA Ranking of Priority Risks

The quantitative scoring of criticality indices indicates that the most ecotoxicologically dangerous defects are not the most visually apparent before application, as synthesized in Table 2. Nozzle orifice expansion shows a high criticality score (C = 40) consistently across all three study locations; this subtle defect alters the spray stream profile, causing chronic involuntary pesticide overdoses. The most severe criticality metrics ("Very High", C = 48) are observed in Bouaké and Korhogo for unclosable tank caps and broken carrying straps, two technical failures that trigger direct spilling of concentrated chemical spray solution onto operators' skin and clothing.

3.3. Spatial Mapping of Chemical Mix Preparation Areas

Spatial analysis of operational crop management highlights sharp behavioral contrasts regarding the mitigation of acute environmental risks during pesticide mixing. In the District of Abidjan, 59% of market gardeners prepare their chemical bouillies outside the field boundaries (in residential areas or near household water sources), compared to 40% who mix them inside production boundaries. Conversely, in the interior basins (Bouaké and Korhogo), pesticide mixing takes place almost exclusively in-situ on the field plots, accounting for 96% and 97.5% of growers respectively, thereby confining accidental spill risks to agricultural zones. The chart below displays the ex-situ vs in-situ distribution for chemical preparation, illustrating localized management habits.

Figure 1. Mapping of Phytosanitary Mix Preparation Sites Across the Three Vegetable Production Hubs.

Figure 1. Mapping of Phytosanitary Mix Preparation Sites Across the Three Vegetable Production Hubs.

3.4. Water Resource Protection Behaviors

Empirical tracking of protection strategies aimed at safeguarding groundwater tables and open irrigation canals points to a near-total absence of eco-responsibility among growers facing diffuse pollution hazards, as illustrated in Figure 2. The situation is critical in the District of Abidjan, where 96% of lettuce smallholders deploy no mitigation or containment steps around neighboring water bodies during sprayer cleaning or chemical treatments. The Korhogo zone shows an intermediate threat profile with 69% unsafe behaviors, while Bouaké displays the highest resource protection rate, though still in the minority (39% safe management). The histogram below emphasizes the behavioral failure relating to water resource preservation, heavily pronounced in metropolitan Abidjan.

3.5. Water Resource Protection Behaviors

Psychological assessment reveals a flagrant contradiction between objective threat levels (85% defective spraying equipment, absence of water resource isolation) and subjective operator safety viewsas illustrated in Figure 3. In Abidjan, despite highly intensive pesticide applications, 89% of smallholders evaluate treatment risks as "low" (50%) to "medium" (39%), with only 10% identifying a high risk. Conversely, market gardeners in Korhogo and Bouaké express greater cognitive clarity, associating chemical applications with mostly moderate-to-high risk levels. The Chi-square test confirms the highly significant dependence of this mental perception upon the geographic environment (2 = 50.12; p < 0.05). The graph below outlines the psychological anchoring bias among Abidjan growers who trivialize chemical threats compared to interior basin smallholders.

4. Discussion

The evaluation of the sprayer fleet exposes a major blind spot within occupational safety frameworks in West African agriculture: the systemic deterioration of the technical application tool (85% failure rate), matching the global crop itinerary non-compliance patterns outlined by [2,3]. The FMECA methodology demonstrates that nozzle orifice widening (C = 40) represents a highly treacherous agronomic risk because it is visually unnoticeable before field use. This widening alters flow rates and droplet size profiles, generating large involuntary chemical overdoses that override application dose calculations from manufacturing firms. Furthermore, leaking caps and cracked shells (C = 48) turn spraying routines into severe dermal exposure events for the operator, who does not wear any personal protective equipment (PPE).

On the psychological level, the systematic risk minimization recorded in Abidjan (89% low-to-medium perception) validates the classic risk perception theories established by [8]. In routine agricultural setups, repeating a hazardous task (chemical spraying) without experiencing immediate acute injuries erodes the cognitive awareness of chronic, long-term toxicity, triggering a social normalization of danger.

This safety underestimation creates a profound cognitive dissonance: market gardeners directly contaminate their own irrigation supplies (96% absence of protection in Abidjan) while possessing theoretical knowledge that pesticides are toxic substances. As detailed by [9], operational trade-offs in informal peri-urban spaces are driven by immediate financial survival. Facing severe land and cash precarity, smallholders sacrifice sprayer maintenance or environmental containment to protect immediate profit margins, matching the risk models described [10] in informal African food chains.

5. Conclusions

The implementation of the FMECA framework across Ivorian vegetable systems proves that mechanical degradation of knapsack sprayers (85% failure rate) is a key amplifier of environmental pollution and occupational poisoning. This physical breakdown is exacerbated by cognitive biases, leading urban smallholders to a routine normalization of chemical hazards and direct water source contamination. Breaking this technical vulnerability cycle requires participatory engineering approaches centered on compulsory nozzle calibration, distribution of low-cost tank repair kits, and community-led training focused on overcoming immediate economic constraints.