Pesticide handling practices and associated ecotoxicological and human health risks among rice farmers in Karonga district, Malawi

Abstract

Background

The quantities, diversity, and frequency of pesticide application among rice farmers in Malawi are steadily increasing to improve crop production. Inappropriate handling and application of pesticides expose farmers and the environment to adverse health risks. The study investigated the level of knowledge on pesticide handling and respective effects on both environment and human health.

Method

A semi-structured questionnaire was used to collect data in the survey involving 399 randomly selected rice farmers. Descriptive statistics analyzed farmers’ socio-demographic profiles and their knowledge of different aspects of pesticide application. Chi-square tests explored the association between socio-demographic characteristics and farmers’ knowledge of different aspects of the pesticides. Logistic regression models were fitted for each binary outcome and the socio-demographic characteristics.

Results

Male farmers aged 55 years and above with education above secondary level were 0.42 times less likely to observe self-protection, aware of the toxicity of different chemicals and the associated environmental effects, hence handled and applied pesticides responsibly. Farmers identified headache and respiratory disorder as the common human health conditions associated with pesticide use. Likewise, more educated farmers, beyond secondary level were 2.37 times more likely to handle good or better pesticide handling and aware of dangers on environmental degradation.

Conclusion

The study found that farmers lacked adequate knowledge about optimal pesticide usage and had insufficient understanding of proper pesticide handling and its respective impacts on humans and the environment. Proper training and information sharing among farmers’ groups are needed.

Introduction

Rice is a staple food crop for above 3 billion people globally [1, 2]. As such, the demand for food rice supply is steadily growing, corresponding to human population growth, and the projected quantities for consumption are expected to surpass 550 million tons by 2050 [3,4,5]. Rice production, however, is labour intensive [6], and the plant is prone to a diverse range of pests and diseases; hence the adoption and intensive application of pesticides is inevitable [7, 8]. Generally, pesticides consist of herbicides, insecticides, fungicides, and bactericides used to control pests and diseases in agriculture to enhance the productivity and quality of crops [9,10,11]. In 2021, an estimated 3.54 million tons of pesticides were applied in agricultural production systems globally, a four percent increase since 2020 [12].

Although the rice yield remains generally low in Africa, the increase in production recorded from the continent corresponds to the increase in cultivation areas [13, 14]. In Malawi, rice is the second staple and economically important food crop grown around the shores of Lake Malawi; Chilwa Lower Shire [15, 16]. Similar to general trends in Africa, rice production in Malawi is low and very unstable and fluctuates from year to year. As such, the country applied approximately 2.36 kilotons of pesticides for agriculture in 2021 [12], at an average rate of 0.6 kg per hectare to increase productivity [3, 17]. This upward trend in the application of pesticides in Malawi has been recorded since 2000, from 0.07 kg per hectare to 0.62 kg per hectare by 2020 [18]. Among the common groups of pesticides are organophosphate, chloroacetanilide, pyrethroid, carbamate, and chlorophenoxy [17].

Pesticides present different levels of toxicity to humans [19, 20] and environment [20, 21]; as such, precautionary measures and guidelines have been developed to reduce the risk of exposure [22, 23]. Pesticide toxicity is categorized into three classes: I, II, and III [24, 25]. Class I pesticides are characterized by high toxicity to humans with low LD50 (lethal dose for 50% of the test population) and include carbofuran methyl, parathion, hexachlorobenzene, and cyfluthrin [23]. Exposure to class I pesticides results in acute poisoning, respiratory distress, skin/eye irritation, and environmental damage [26,27,28] and requires comprehensive protective measures [28]. Class II, on the other hand, is classified by moderate toxicity and includes profenofos, alachlor, chlorpyrifos, cypermethrin, lambda-cyhalothrin, dichlorodiphenyltrichloroethane (DDT), and 2,4-D [23]. Exposure to class II pesticides results in effects such as mild irritation, nausea, headache, and dizziness [27, 28]. Class III pesticides are characterized by slight toxicity and include glyphosate and acetochlor. Exposure to class III pesticides leads to minimal irritation to the skin, eyes, or respiratory systems [29] and also lowers the risk of systemic effects and mild but temporary symptoms such as dizziness, nausea, and headache. Pesticides can accumulate in the tissues of organisms and the environment, such as water, air, soil, and sediments [30,31,32,33]. Therefore, excessive exposure to and use of pesticides pose serious health risks to humans and livestock as well as pollute the environment [10, 24, 33,34,35].

Humans are exposed to pesticides during handling and management, especially mixing, loading, spraying, and cleaning of application equipment [36,37,38]. In addition, farmers are exposed during re-entry into pesticide-treated crops and close interaction with contaminated tools [39, 40]. Upon exposure, handlers may experience headaches, nausea, and skin and eye irritation in the short term [26,27,28, 30]. However, prolonged exposure to pesticides may induce cancer and other neurological disorders [41, 42]. Meanwhile, excessive and irresponsible application of pesticides poses a significant pollution threat to the environment including decimation of non-target organisms such as birds, fish, bees, and plants [32, 33, 43]. Besides, some pesticides, e.g. DDT degrade slowly with a half-life of 2 to 15 years; can accumulate in the soil [24, 44] or accumulate in other organisms upstream the food chain or concentrate in the same organism [24, 42], reaching toxic levels over time. Other pesticides, including DDT and chlorpyrifos, degrade derivatives that are more toxic than the parent chemical, hence posing health threats to both humans and the environment [45, 46]. Failure to follow pesticide guidelines resulting in improper handling is likely to increase detrimental effects on the health of the handlers, the environment, and biodiversity [21, 47, 48].

Many countries, therefore, adopted guidelines to ensure responsible handling and application of pesticides to protect users and the environment [22, 23, 49]. Indeed, Malawi has laws and regulations to encourage safe pesticide use [35, 50]. However, with the widespread illiteracy reaching 33.75% [51], poverty levels of 58.8% [51, 52], and predominantly subsistence farming, farmers rarely adopt and/or adhere to the set guidelines [53]. In this regard, farmers are likely exposed to toxic pesticides during handling and use [35, 49, 53,54,55]. However, limited data is available to ascertain the level of knowledge towards adhering to safe handling and use of pesticides especially during mixing and application. Understanding the effects of pesticides on human health and the associated environmental pollution underpins the choice of chemicals for use [47, 48, 56]. Owing to a lack of information on the level of awareness among farmers about the side effects of chemicals to on humans and the environment in Malawi, the adherence to best practices in pesticide choice and use is undoubtedly poor. The study aimed at generating data on the level of knowledge on the appropriate use, protection, and awareness about the effects on the environment and health among the rice farmers in Karonga district, Malawi. The information generated will guide government initiatives such as training and provision of application equipment and personal protective equipment (PPE) to ensure responsible pesticide use for sustainable production of high quantity and quality rice for the local and export markets.

Materials and methods

Study area

The study was conducted in Karonga district, the largest rice-growing district in Malawi (Fig. 1), located at 9.9036$^\circ$ S, 33.9750$^\circ$ E, and at an altitude of 488 m above sea level.

Fig. 1

Rice-producing zones of Karonga, Malawi, Africa. Source. Kanyika-Mbewe 2024

Study design, sample size, and sample determination

The cross-sectional study was conducted among rice farmers in Karonga. The district is the largest rice-producing district in Malawi. Farmers were selected using a systematic random sampling technique from three Extension planning areas (EPA): Kaporo North, Kaporo South, and Vinthukutu, in three traditional authorities (Mwakaboko, Kilupula, and Wasambo), and consented before participation. The district has approximately 35,000 rice farmers, out of which 339 (consisting of 185 males and 154 female respondents) were sampled for the survey using formula (1). The selected sample size ensured a representative group with an acceptable margin of error and provided statistical reliability for the survey.

$$n=\frac{{z}^{2}.p(1-p)}{{e}^{2}}$$

(1)

where n = sample size, z = critical value of the desired level of confidence at (95%) = 1.96, p = standard deviation (50%) = 0.5, e = margin of error/desired level of precision at 0.06.

Data collection

A semi-structured questionnaire was used to collect data in the survey. The questionnaire was prepared in English and later translated into the local language (Tumbuka) to facilitate farmers' understanding of the questions. The questionnaire had six sections: (i) social demographic data, (ii) pesticide handling and application, (iii) safety and precaution measures, (iv) farmers' knowledge of pesticide usage, (v) health effects after exposure, and (vi) the environment (water sources). The questionnaire was pretested before data collection to ensure reliability, validity, and clarity of the instrument. The questionnaire has been uploaded as a supplementary file (SF1). The WHO-recommended classification of pesticides was used to classify different pesticides used in the region [23].

Data analysis

Data were analyzed using STATA version 16.0 (Stata Corp, College Station, TX, USA). Descriptive statistics were generated and displayed in graphs, including frequency, and percentage of farmers’ socio-demographic profiles and their knowledge of different aspects of pesticide application. Chi-square tests were used to explore the association between socio-demographic characteristics and farmers’ knowledge of different aspects of the pesticides. Logistic regression models were fitted for each binary outcome and the socio-demographic characteristics at $\propto$ 0.05.

Results

Synthetic pesticides used in rice farming

During the survey, 10 different active ingredients in pesticides used in rice fields, singly or in combinations, belonging to five chemical classes, were recorded (Table 1). The pesticides recorded consist of five herbicides dominated by 2, 4-Dichlorophenoxyacetic acid and six insecticides dominated by Cypermethrin. Among the five chemical classes, organophosphate-based pesticides constituted 33.70% of all the chemicals used. All the pesticides applied in Karonga rice fields belong to categories Ia and III of toxicity, with the majority used moderately hazardous (WHO class II). However, a notable 6.20% of the chemicals used fall under toxicity class Ia (extremely hazardous) and Ib (highly hazardous). Apart from synthetic pesticides, other farmers used natural repellents, such as the application of extracts from the neem tree.

Table 1 The frequency of active ingredients and level of toxicity of different classes of pesticides used in rice fields in Karonga, Malawi

General information on the socio-demographic characteristics

The study involved 339 respondents, consisting of 54.6% male and 45.4% female, aged between 16 and above 55 years. The majority of the respondents (97%) had received some form of education, with more than half (54.3%) having completed primary school while 43.1% had either attended secondary or higher education (Table S1). Furthermore, more than half of the respondents, 56.6%, had more than 12 years of experience in rice farming (Table S1).

Pesticide handling and self-reported side effects

Up to 41% of the respondents did not use personal protective equipment (Figs. 2A and 3D). Among the farmers who used some PPE, only 5.72% wore complete suits/cloth overalls. Concerning self-reported side effects, approximately 54% of the respondents reported experiencing at least one or more acute symptoms after handling pesticides. Nonetheless, 19.83% did not ascribe any health problems to pesticide exposure (Fig. 2B). The most frequently reported symptoms included headaches (16.38%), respiratory disorder (14.66%), and eye irritation and tears (12.07%).

Fig. 2

The frequency of A use and disuse of personal protective equipment and B self-reporting side effects among rice farmers in Karonga

Fig. 3

Ways of handling pesticides A mixing B and C disposal of empty pesticide containers and D spraying

Storage of pesticides and management of waste

A large proportion of farmers (86.22%) stored pesticides inside houses; 7.04% in the basement and 1.47% in attached outbuildings (sheds), and some farmers stored pesticides on the veranda (Fig. 4). Furthermore, most farmers (73.45%) do not take any precautionary measures when disposing of empty chemical bottles before or after spraying pesticides (Table S2, Fig. 3B, and C).

Fig. 4

The storage places of pesticides within homesteads utilized by farmers in Karonga district

Farmers’ knowledge on the effects on ecosystems associated with pesticide usage

Most farmers were not aware of pesticide-related water and air contamination and possible causes of death of fish, frogs, and birds (Table S2). Additionally, more than half (72.86%) of the farmers reported having eaten organisms harvested within the farms’ environment. The majority; 77.29% of the farmers were unaware of the duration of post-pesticide application near the habitat to harvest any organisms for consumption.

Regarding the main water source for drinking, 76.70% of farmers relied on boreholes, 5.90% used tap water, 8.55% used protected wells (covered), and some 7.08% depended on unprotected wells. Although more than half (59.88%) took precautionary measures to protect domestic animals before or after spraying pesticides, 61.60% of the farmers mixed and applied pesticides within less than 50 to 100 m from drinking water sources. Only 24.19% of farmers used water sources that were more than 100 m away from where the pesticides were mixed/applied (Fig. 3A, Table S2).

Farmers’ practices relating to perceived health risks of pesticide use, appropriate dosage, and use of PPEs

Results of the analysis of farmers’ practices on pesticide use, appropriate dosage, and use of PPEs are shown in Table S3. A test of goodness of fit with farmers’ practices was statistically significant: male and practice on safe pesticide use ($\chi^2=4.24,\;p<0.040)$, education level of farmers and practice of safe pesticide use ($\chi^2=9.88,\;p<0.007)$; education level of farmers and practice of PPE use ($\chi^2=6.91,\;p<0.032)$, female and appropriate pesticide dose ($\chi^2=10.64,\;p<0.01)$, farmers’ age group and appropriate pesticide dosage ($\chi^2=10.20,\;p<0.037)$. However, the chi-square ${(\chi }^{2})$ of other characteristics was not significant. For example, whether poor pesticide use could cause health problems for humans and the environment, or whether inappropriate PPE use could negatively affect humans, were not statistically significant. These results were negatively associated with a greater percentage of farmers responding “No,” implying that these practices are not deemed relevant. Additionally, neither gender, age, nor education level significantly influenced farmers’ attitudes toward pesticide use.

Factors influencing knowledge of farmers towards environmental degradation

A bivariate analytic model showed relatedness of several characteristics with farmers' knowledge of the use of pesticides and environmental degradation (water contamination and death of fish and other living organisms in the ecosystem), including sex, age group, education level, or duration in farming (Table S4). In multivariable regression analysis, farmers aged 55 years and above with secondary education and more were significantly aware of the potential water contamination and death of organisms caused by exposure to pesticides. As such, farmers (above 55 years) were 0.42 times less likely to adhere to better pesticide handling practices and a greater understanding of environmental degradation [AOR = 0.042, 95% CI (0.17, 0.97)] as compared to farmers between 36 and 45 years of age. Further, farmers attaining secondary education, and higher were 2.37 times more likely to adhere to better pesticide handling and knowledge of environmental degradation [AOR = 2.37, 95% CI (1.41, 3.97)] as compared with farmers with primary education. Meanwhile, the sex of rice farmers did not appear to influence the understanding of the effects associated with pesticides on environmental degradation.

Discussion

The pesticides most commonly used by farmers in the study area are associated with potentially toxic effects, Class (II), according to WHO [24]. Chlorophenoxy pesticide (2, 4-Dichlorophenoxy acetic acid) was used by most farmers in rice production, which falls in class (II) of toxicity [24, 56]. Farmers used moderately hazardous pesticides, such as 2, 4-D, profenofos, chlorpyrifos, and cypermethrin, consistent with findings of previous studies [57, 58]. Normally, the extensive use of moderately hazardous pesticides raises significant concerns regarding potential environmental and human health. Even though the pesticides used are not as toxic as class I, the cumulative effects in areas with a high frequency of application could endanger human health. Additionally, previous studies reported many instances where pesticides with different active ingredients that had different toxicity were applied in rice farms [38], which is the same case with this study. However, there were no reports of the usage of restricted pesticides like dichlorodiphenyltrichloroethane (DDT) and its metabolites.

Improper handling of pesticides can negatively affect humans, animals, and the environment [31]. A considerable number of rice farmers asserted that pesticides cause health problems in humans, animals, and ecology when poorly handled during storage and application [59]. Results showed commonly self-reported symptoms among farmers, including headache, respiratory disorder, eye irritation and tears, nausea, stomachache, blurred vision, seizure, and loss of appetite. The most common symptoms were headache, respiratory disorders, and lacrimation nervous disorder, consistent with an earlier finding [25]. Additionally, skin, throat, and eye irritation; difficulty in breathing, coughing; and headache remain major health issues as reported by farmers after pesticide application [28, 29, 60]. Similar findings have been documented in studies conducted in Ethiopia [29], Nigeria [61], and Ghana [26]. Respiratory disorder can be manifested by coughing, shortness of breath, or chest discomfort [62,63,64]. The most commonly reported potential effects of chemical exposure that lasted at least three days were skin irritation (74.4%), vomiting (90%), diarrhea (97.4%), headache (66.7%), and dizziness (80.7%) [62].

As one of the ways of protecting farmers from adverse exposure to pesticides, PPEs are recommended to be used. Normally PPE includes foot protection, hand protection, body protection, eye protection, and mouth protection. Unfortunately, most of the farmers did not use PPE during the mixing and application of pesticides, yet it is significantly important in reducing chemical exposure [63]. Respondents used partial PPE as some were considered as not important, while others had no access. The findings of this study are consistent with previous research conducted in Malaysia [62] and the Central Rift Valley of Ethiopia [64]. In Malaysia, farmers used long-sleeve shirts and trousers, face masks, and boots during the mixing or loading and application of pesticides, albeit without gloves, increasing dermal exposures [38]. In agreement, some researchers [28] have indicated that health symptoms can be linked to the inappropriate and inadequate use of PPE during pesticide application. Chemical mixing is a major exposure pathway to pesticides among farmers [9]. A considerable number of the farmers were exposed to the chemicals during mixing and application. Similar studies in the Caribbean have reported overall low adherence to the use of recommended PPE [27, 65].

The present study revealed that pesticides were frequently stored in houses where farmers dwelled, rather than in separate storage spaces. This is a clear indication that farmers lacked knowledge regarding appropriate ways of storing pesticides. Storage of pesticides in the houses and veranda increases the potential risks of exposure. Reports from previous studies highlight that nearly 55.5% of farmers stored pesticides in houses, without considering the potential health effects [28, 39, 49]. Contrary to the findings of the present study, storage of pesticides in separate places away from the dwelling-in houses was better in Chitwan district, Nepal [66]. Besides that, the bush was considered the main storage facility in the western region of Ghana to protect people and domestic animals [28], which was not the case in this study, where no preventive measures were followed to protect domestic animals. Even though some studies adhered to proper storage, the case of Brebes differs; leftovers were kept in the kitchen or bedroom along with pesticide spraying equipment [27, 67].

Concerning the management of empty containers, the study showed that no caution was taken on the disposal of empty containers of pesticides, similar results were reported elsewhere [22]. Worryingly, it was disheartening to observe that no caution was taken in disposal practices, posing a significant risk to both the environment and public health. Poor disposal of empty containers or leftover pesticides can not only seep and contaminate the soil but can also disrupt natural ecosystems [20, 68].

Most of the farmers in the present study had advanced knowledge of pesticide usage, though they did not use protective equipment during mixing or application. This shows a clear disconnect between the understanding of pesticide safety and actual practices. Despite the awareness of proper usage of pesticides, many neglected essential protective measures. The inability to follow safety measures might be directly related to the means of accessing PPEs, which might also be linked to the source of income. Most farmers rely on farming as a source of income, like the findings of the study by [25], which reported the dependency on agriculture for a living in 88% of the farmers. Additionally, farmers are aware of the link between pesticide usage and associated human ailments [28]. Furthermore, a high prevalence of illiteracy makes it challenging for farmers to understand and comply with safety recommendations while using pesticides.

Most farmers had limited knowledge of the impacts of pesticides on human health, primarily due to a lack of training on the safe use of pesticides and potential health risks [67]. This lack of awareness not only compromises the issues of farmers’ health but also poses broader risks to families and communities. As a result, understanding of the long-term consequences of pesticide exposure remains limited.

Poor practices of handling pesticides can be influenced by educational background, attitude, and age. Farmers with higher education have a capacity of understanding the importance of PPEs for protection from various health risks; this was the case with the current study. Previous studies among sugarcane growers revealed that those who had completed tertiary education applied good practices in pesticide usage [38]. Besides, farmers’ attitudes to the designs of PPEs hampered their use. Farmers claim that PPE designs were not user-friendly and hindered their physical flexibility [69]. Additionally, farmers aged 55 years and above demonstrated greater awareness of pesticide handling practices, possibly attributed to long-term experience working with pesticides [65].

Accessibility to appropriate protective gear remains a contributing factor to the poor handling of pesticides [70]. In the current study, few farmers exhibited safe or potentially safe behavior, especially in the use of PPE. One probable explanation for this tendency is that PPEs, such as protective gloves, boots, and goggles, are simple but not easily accessible. This leaves the farmers vulnerable without the basic protection to safeguard their health.

The increase in the age of farmers is associated positively with knowledge of the effect of pesticides on water contamination. Farmers of 55 years and above were more conversant with the effect of pesticides on water sources, probably due to knowledge and experience. This was contrary to the findings from other studies [64] that reported that an increase in a farmer’s age is linked to low knowledge of pesticides. Furthermore, the study found that farmers with secondary and higher education have more understanding of the death of fish. Previous studies agree with the findings of this study [28]; farmers will be capable of reading the labels and undertaking good agricultural practices.

Human health risk and ecotoxicology of pesticides

Farmers’ exposure to acute pesticide doses can have negative effects on the ecosystem and human health [65]. The current study highlights unsafe practices that potentially affect humans and the environment; numerous side effects, such as skin or eye irritation, blurred vision, and headache, have been reported, suggesting the signs and symptoms of medical problems [71]. Poor pesticide practices increase the danger of exposure directly or indirectly, raising the possibility of immediate harmful chemical effects.

Water source contamination is not only a threat to human health but also to aquatic life. Farmers with higher levels of education had more knowledge of the effects of pesticides on the environment and the possible death of fish and other organisms in the ecosystems. Pesticide residue contamination in surface and groundwater is exceedingly harmful to the survival of aquatic species, as well as soil microorganisms [72]. Farmers also reported water contamination in this study.

Conclusion and recommendations

In the battle against pests, profenofos, 2, 4-D, chlorpyrifos, and cypermethrin were commonly used in rice farming, and these fall within class II of the WHO classification of toxicity. However, their intensive use presents serious risks that affect human health and also contaminate the environment. This study showed the visible acute health effects experienced by rice farmers that are closely linked to pesticide exposure. The self-reported effects included headache, respiratory disorder, eye irritation and tears, nausea, stomachache, blurred vision, and even seizures.

Despite the available documentation, most farmers lack knowledge of proper pesticide handling. The current study reveals a significant gap, especially regarding optimal pesticide usage, the importance of PPEs, and the broader environmental and human health consequences of misuse. Most farmers do not use PPEs, either due to a lack of awareness or because of a lack of accessibility. Therefore, there is a need to raise farmers' pesticide knowledge and awareness by giving training on the health-related impacts of pesticide exposure, the impact of pesticides on the environment, and pesticide handling. Besides that, the use of less toxic or bio-pesticides should be promoted among farmers to reduce environmental health risks.

Additionally, it is recommended here that retailers be trained to enhance their understanding of pesticide safety and proper usage because they are not only a primary source of information for farmers but also equip them with accurate knowledge for improving pesticide handling practices. Finally, policymakers should also integrate pest management strategies that safeguard crop health while minimizing human and environmental risks. For example, the adoption of one health concept by utilizing pesticides to safeguard crop health while reducing hazards to human health and environmental systems and guaranteeing food security.