Interventions to Reduce Pesticide Exposure from the Agricultural Sector in Africa: A Workshop Report.

Despite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.

Dietary risk assessment of organochlorine pesticide residues in maize-based complementary breakfast food products in Nigeria.

The study assessed the levels of organochlorine pesticides (OCPs) in eight brands (A-H) of regularly consumed maize-based complementary/breakfast foods in Nigeria. We also evaluated the dietary exposure of infants and young children to the detected OCPs. The OCP residues were quantified using GC-ECD. A total of 10 OCPs residues (ß-HCH, δ- HCH, heptachlor, endosulfan sulfate, aldrin, endrin, dieldrin, p,p'-DDE, p,p'-DDT and methoxychlor) were detected. Total OCPs burden was highest in brands F, D, and G with mean concentrations of 45.98 mg kg-1, 28.54 mg kg-1 and 21.87 mg kg-1, respectively and the lowest burdens in brands H (1.72 mg kg-1) and A (6.61 mg kg-1). Hazard index (HI) for all the age categories were >1 and all the 6 carcinogens (ß-HCH, heptachlor, aldrin, dieldrin, p,p'-DDE, and p,p'-DDT) identified had cancer risk index range of 5.43 × 10-4 to 2.05 × 10-6 which were above acceptable risk. These results indicated the possibility of both systemic and cancer risks to infants and children consumers of the foods. Food brands manufacturers need to carry out regular pesticide residues analysis of raw materials especially maize prior to the production in order to ensure food safety and quality.

Insecticide residues in the blood serum and domestic water source of cacao farmers in Southwestern Nigeria.

The blood serum of cacao farmers and their domestic water sources were analyzed for insecticide residues in selected cacao growing communities of Southwestern Nigeria. The farmers were grouped into five exposure periods based on their years of involvement in insecticide application, viz, <5 years, 5-9 years, 10-14 years, 15-19 years and >20 years. The residue analyses revealed that 42 out of the 76 farmers had residues of diazinon, endosulfan, propoxur and lindane in their blood; and 47.6% out of these farmers belonged in the >20 years exposure duration period. About 34% of the farmers had diazinon with a mean concentration of 0.067 mg kg(-1), 29% endosulfan (mean=0.033 mg kg(-1)), 23% propoxur (mean=0.095 mg kg(-1)), and 17% lindane (mean=0.080 mg kg(-1)) in their blood. The residues of lindane, endosulfan and propoxur in all the exposure duration categories were found to be far below the no observable adverse effect level (NOAEL) while diazinon residues detected in the blood serum of the farmers in all the exposure duration categories exceeded the NOAEL of 0.02 mg kg(-1) for the insecticide. The study also revealed that the sources of drinking water had been contaminated with dazinon and propoxur in some of the farmers' localities; and the concentrations of the insecticides exceeded the acceptable daily intake (ADI). It is concluded that cacao farmers in Southwestern Nigeria may have been occupationally exposed due to insecticide application for mirid control in their cacao plantations; and the exposure at times is of such magnitude as to be hazardous to the farmers and their respective communities.

Erythrocyte cholinesterase enzyme activity and hemoglobin values in cacao farmers of southwestern Nigeria as related to insecticide exposure.

The blood of 76 cacao farmers from Southwestern Nigeria was monitored for erythrocyte cholinesterase enzyme activity (AChE) and hemoglobin values before and after insecticide application. Eight farmers had 30% to 50% baseline AChE activity, which suggests chronic organophosphate insecticide poisoning. AChE activity inhibition suggestive of occupational exposure (20% to 30%) was manifested by 28% of the farmers, whereas 30% to 50% inhibition suggestive of hazard was manifested by 11%. Significantly depressed post-insecticide application hemoglobin values were similarly recorded among the farmers. AChE activity inhibition, depression in hemoglobin values, and the years of involvement of the farmers in insecticide application on cacao, were positively correlated. Occupational exposure hazard due to organophosphate insecticides is therefore real among cacao farmers in Southwestern Nigeria. Regular biomonitoring of their blood for AChE activity and hemoglobin level is necessary.

Occupational insecticide exposure and perception of safety measures among cacao farmers in southwestern Nigeria.

The authors assessed occupational exposure hazards among cacao farmers in Southwestern Nigeria. They administered structured questionnaires, supplemented with oral interviews, to 150 farmers to obtain information on insecticide use and perception of safety measures. The farmers used lindane, diazinon, endosulfan, and propoxur for cacao mirid control. Factors promoting exposure included eating and drinking during spraying operations, failure to use protective clothing, improper storage and disposal of insecticides. Varying proportions of the farmers experienced common symptoms associated with exposure hazards. Few presented for medical treatment with complaints of frequent fever, strained breathing, sleeplessness, loss of memory, etc., symptoms which are suggestive of chronic pesticide poisoning. The authors concluded that biological monitoring of the effects of insecticides on the health of the farmers is urgently needed together with awareness campaign and training on pesticide safety measures.