Cotton is an important crop in Tanzania, with over half-a-million households relying on cotton cultivation for their primary source of income.
A new study, published in Toxics, reveals significant levels of pesticide poisoning among Tanzanian smallholder cotton growers following occupational exposure to highly hazardous pesticides (HHPs).
Of the 1,074 cotton farmers and farm workers interviewed, 48% of respondents had experienced symptoms of acute pesticide poisoning within the previous 12 months. Only 6% of those reporting poisoning incidents sought medical treatment in a formal healthcare setting, suggesting that the scale of pesticide poisoning is significantly underreported. The study also highlights a gendered aspect to pesticide exposure, with men more likely to report pesticide poisoning. Women reported varied activities at time of exposure, such as entering a recently treated field, or cleaning clothing and equipment contaminated with pesticides.
Strikingly, over 80% of the reported poisoning incidents were associated with just four pesticide active ingredients: profenofos, lambda-cyhalothrin, chlorpyrifos and cypermethrin.
Raphael John Mwezi, Head of the Toxicology Unit at Tanzania Plant Health and Pesticides Authority said, “The large-scale study provides important new evidence of the impact of hazardous pesticide use on the health of farmers and workers in Tanzania. The large numbers of farmers reporting pesticide poisoning is alarming and warrants swift action, particularly in relation to the few pesticides that were associated with most of the incidents.”
Cotton pickers in a cotton field in Mwanza, Tanzania. Credit: Pravine / Shutterstock.com
Profenofos, an organophosphate insecticide, is banned in at least 34 countries. It is one of the most commonly used pesticides in Africa and is used extensively in cotton production globally. The study found that it was associated with 252 incidents in the last 12 months, with symptoms including strained breathing, a persistent and painful cough, visual disturbances, extreme agitation and loss of consciousness.
Co-formulations of chlorpyrifos, an organophosphate insecticide, and cypermethrin, a synthetic-pyrethroid insecticide, were associated with 184 incidents in the last 12 months. Frequently reported symptoms included nasal, throat and skin irritation, persistent and painful coughs, muscle weakness, slurred speech, extreme agitation and seizures. Chlorpyrifos is currently under consideration for listing under both the Stockholm and Rotterdam conventions due to its harmful effects on human health and the environment.
Professor Andrea Rother, Head of Environmental Health Division and Associate Professor in the School of Public Health and Family Medicine, University of Cape Town said, “Promoting personal protective equipment (PPE) is widely seen as sufficient to protect people from pesticide exposure. The study shows that this is not the case. Although training on PPE use can play a limited role in reducing pesticide exposure, it does not address gendered and climatic conditions in Africa, and access to inappropriate PPE. Thus, as the study highlights, PPE use does not significantly reduce Unintentional Acute Pesticide Poisoning (UAPP).”
Given the well-documented adverse effects of these chemicals on human health, this study clearly indicates an urgent need for improved pesticide regulation, the scale up of community surveillance and the promotion of less hazardous alternatives to the use of HHPs. To support this, the authors point out that a range of alternative pest management options are available to replace HHP use in cotton when used in an integrated approach. Indeed, the rapid growth of organic cotton production in Tanzania highlights the potential for HHP-free cotton cultivation.
Professor Deodatus Kakoko, Dean of the School of Public Health and Social Sciences at Muhimbili University of Health and Allied Sciences (MUHAS) in Tanzania said, “This robust study reveals a significant problem of pesticide poisoning in Tanzania. It is a very welcome addition to the body of scientific evidence on this neglected topic. More routine surveillance is needed to detect such problems in future.”
