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Table of Content ... 1

Preface ... 3

Pesticides and occupational health ... 3

Pesticides ... 4

Pesticide hazard list ... 4

Uganda and pesticides ... 5

Search strategy ... 6

The framework of the project ... 6

Article ... 8

Pesticide use and how it affects the health of small scale farmers in Uganda: a cross-sectional study ... 9

Abstract ... 9

Background ... 10

Method ... 12

Study design ... 12

Setting ... 12

Participants ... 12

Standardized interviews ... 13

Exposure variables ... 14

Outcome variables ... 14

Potential confounders ... 15

Statistical method ... 15

Missing data ... 15

Ethical considerations ... 16

Results ... 17

Participants ... 17

Crops ... 17

Pesticides ... 17

Symptoms ... 18

Knowledge ... 18

Practice and attitude ... 18

Association between symptoms and pesticide usage ... 18

Supplementary analyses ... 20

Discussion ... 21

Conclusion ... 24

Tables for Pesticide use by Ugandan small scale farmers: a cross sectional study. ... 25

Table 1 ... 25



Table 2 ... 26

Figure 1 ... 27

Table 3 ... 28

Figure 2 ... 29

Figure 3 ... 30

Table 4 ... 31

Table 5 ... 32

Table 6 ... 34

Table 7 ... 35

Table 8 ... 36

Reference List ... 37

Appendix ... 40

Appendix 1 ... 41

Appendix 2 ... 47

Appendix 3 ... 56





The World Health Organization has estimated a worldwide incidence of 3.000.000 cases of acute and severe poisoning. 300.000 of these cases are fatal. Nearly all of these deaths occurred in developing countries. The effortless availability of highly toxic pesticides in farmers’ homes has made pesticides the most common remedy for suicide [1-3].

Approximately one third of the deaths are due to occupational hazards, as the extensive use of pesticides exposes farmers to both long term and acute occupational health problems [4, 5]. In addition to this comes an even greater number of unreported cases of mild-to-moderate intoxication [4, 6, 7].

Medical treatment in the rural areas is difficult since few medical resources are available. Case fatality rates for pesticide poisoning are often high in developing countries due to lack of the necessary equipment, medicine and sufficient educated medical staff [5]. The necessity of ensuring agricultural production and food security in low-income countries while also protecting the population against health impacts following exposure to pesticides has emerged as a major global public health problem [5].




Pesticides are poisonous chemicals intended for preventing, destroying or controlling pests during the production, processing, transporting and marketing of food. This includes vectors of human and animal disease, unwanted species of plants or animals causing harm during the production, processing, storage, transport or marketing of food, wood or animal feedstuffs [8]. They are mainly used in agriculture, but can also be used in health campaigns; e.g. to eradicate vector diseases such as yellow fever and malaria.

Approximately 1.500 active ingredients have been registered as pesticides, and 50.000 commercial pesticides are registered for use. Because of the enormous number of commercial formulations, pesticides are available in almost any community [9].

The health effects of pesticides can be divided into acute poisoning and chronic effects. Acute pesticide poisoning is any illness or health affects appearing shortly after a single or multiple doses of pesticide.

This includes a wide range of reactions in different target organs like neurological, dermal or respiratory.

Chronic poisoning occurs gradually after prolonged exposure to pesticides. Increasing development of cancer and reproductive abnormalities have been seen in people who have gone through a long-term exposure to pesticides. This study will focus on the short-term effects of pesticide poisoning [6, 7, 10, 11].


In an effort to accommodate the improper use of pesticides, the World Health Organisation (WHO) has made an Essential Drug List (EDL), classifying the pesticides into five groups according to their health hazards; Ia = Extremely hazardous; Ib = Highly hazardous; II = Moderately hazardous; III = slightly hazardous; U = Unlikely to present acute hazard in normal use. The hazards described are the acute risks to one’s health (i.e. the risk that emerges from a single exposure or multiple exposures over a relatively short period of time). The EDL is primarily based on oral and dermal danger [12]. WHO accentuates the importance of products classified with a high degree of hazard, especially Ia and Ib, being labelled correctly. These labels should indicate the high degree of hazard by skull and crossbones pictures and, furthermore, having colour coding and phrases saying ―toxic‖ or ―poison‖. WHO also accentuates the importance of labels being formulated in the respective local language. The presentation of the symbol and phrase should thus provide the user with sufficient knowledge when choosing a pesticide [12]. Some of the most dangerous classes of pesticides are chlorinated hydrocarbons, organophosphates and

dithiocarbamate pesticides, due to a high index of toxicity [4]. Numerous studies have explored the health effects of organophosphate in developing countries, and have found an increased risk of pesticide

poisoning [13-15].

The Food and Agriculture Organisation of the United Nations (FAO) indicates that developing countries, rather than the least developed nations, consumed the majority of reported organophosphates and


5 dithiocarbamates. This finding is not surprising since pesticides are expensive, and older and cheaper pesticides becomes preferred alternatives to the newer and often safer ones [7].

The pesticide industry is an important player in this problem. The use and selling of pesticides has become a billion dollar business for many national and international agents. The industry states that they are fully supporting police restricted use of pesticides. However, the industry’s interests in profit makes them willing to sell pesticides in developing countries that are already banned in industrialized countries [5, 11, 16]. This results in products of the most toxic classes, like the ones mentioned above, being sold to farmers in developing countries [17]. Moreover, if the pesticide industry keeps paying sales persons on a commission basis, it is unlikely that the dealers will encourage the farmers to use fewer pesticides [4].

The Food and Agriculture Organisation of the United Nations (FAO) has, with its code of conduct, tried to control the use of pesticides. This code of conduct was one of the first voluntary codes of conduct in support of increased food security, while at the same time protecting human health and the environment.

The original FAO code of conduct was published in 1985, trying to encourage long-term efforts to develop legislation, regulations, and infrastructure in order to enforce good pesticide practice [4, 8, 18].

FAO recommend Integrated Pest Management (IPM) to deal with the present pesticide issues. IPM can reduce the use of agrochemicals, improve management and optimize ecosystem mechanisms for pest control/soil enrichment, while also protecting both farmers and the environment [5]. Sustainability is ensured by preparing the communities, building on available local resources and commitments, weaving IPM into local community development planning processes and situating program concerns within the local government system [4].


Pesticide use in Africa accounts for 2-4% of the global pesticide market. This is in comparison to 30% in North America and 16% in Asia [19, 20]. During the period 1993-94, FAO estimated that about 100,000 tons of pesticides were applied in developing countries, of which 20,000 tons were applied in Africa [8, 21]. In Africa, it is estimated that 11 million cases of pesticide overexposure occur annually [4].

Data gathering for the present study has taken place in Uganda. Uganda was one of the first countries to be included in the Danish programme coordination identified in 1989 after the present Ugandan

government of the National Resistance Movement came to power in 1986. The BNI per capita is around

$350, and 31% live in extreme poverty. The size of the country is 241.551 km2, and the population density is 123 persons/km2. The population size is about 28 million people, and the fertility rate is 6.5.

The life expectancy is 50 years. The most prevalent diseases are diarrhoea, airway tract infections, malaria and HIV/AIDS. The illiteracy rate is 31%, and women account for 75% of this [22].

Agriculture plays a vital role of the Ugandan economy. It contributes to roughly 21% of the Gross Domestic Product, and 85% of the population work either directly or indirectly in the agricultural sector [21]. Uganda is currently reported to be among one of the countries in Africa with the lowest pesticide


6 usage rate at only 17 kg/ha. However, with a growing population and thereby a growing crop production, the import of pesticides are increasing. Exact numbers are difficult to acquire, but the import of pesticides has risen with a factor 47 from 1980 to 2004. On top of that, it is estimated that at least another 25% of the actual use is smuggled into the country over non-secured borders [21, 22].


To identify relevant articles in relation to pesticide use and poisoning in developing countries, literature researches were done from September to November 2010, looking for relevant articles in both national and international public health databases using SveMed+, Cochrane and PubMed.

The search strategy was the same in each database using ‖advanced search‖.

The main search words being used were ―pesticide‖ and ―poisoning‖ or ―toxic‖, all of them being truncated. This resulted in only one relevant article in SveMed+.

Searching for reviews with the same words in Cochrane gave 34 hits. Many of these reviews dealt with treatment of poisoning with organophosphate and were irrelevant for this study. Also, a lot of them were references to the Cochrane Injuries Group (CIG). CIG is an editorial base with the purpose of preparing, maintaining and promoting the accessibility of systematic reviews in the prevention field, including poisoning. Eight reviews dealt with poisoning. However, all of these also concerned treatment of pesticide poisoning which was not relevant for this study.

PubMed had 13437 hits. To narrow this number down, different combinations were made, with the following words: ―Developing countries‖ or ―Africa‖ or ―Uganda‖. Also ―knowledge‖, ―practice‖ and

―attitude‖ were used, both combined and divided. Furthermore, the abbreviation ―KAP‖ was also used.

―Small-scale farmers‖, ―small scale farmers‖ and ―small holders‖ were used. All words were truncated and combined with either AND or OR, according to the relevance. Relevant abstracts from the different hits were read through, resulting in 48 articles with the criteria of being either; a cross sectional study, looking at self-reported incident of pesticide poisoning, located in Africa or concerned with knowledge in relation to pesticides.

Apart from these, relevant reports from the WHO or FAO were included.


The project is a collaboration between the Danish NGO, Dialogos and the Ugandan NGO, Uganda National Association of Community and Occupational Health (UNACOH). UNACHO wishes to promote a healthy and productive Ugandan population, and has been involved in several Ugandan occupational health projects. Dialogos has worked with occupational health in developing countries since 1993. It wants to assist developing countries in their self-chosen pathway away from poverty.

The present project is called ―Pesticide use, health and environment in Uganda–. Project‖ and is a three year intervention study of farmers´ pesticide use, health and environment in Uganda running from


7 summer of 2010 -2013. The general objective of the intervention project is to reduce negative health effects of pesticides in humans and prevent pesticide pollution of the environment.

Moreover, Dialogos are working together with ICOEPH (International Centre for Occupational and Environmental Medicine and Public Health) on this project. ICOEPH is a centre formed by professionals and institutions with profound knowledge and experience in the fields of occupational medicine, environmental medicine and public health. ICOEPH and Dialogos have been working together for the past eight years on IPM and ―Pesticides, Health and Environment‖ in Bolivia, and have gained experience in minimising pesticide problems in most developing countries.

In Denmark, a steering committee is responsible for the technical management and guidance of the Ugandan project. The committee consists of volunteers from Dialogos, ICOEPH and the universities.

Dialogos is responsible for managing the funds for the project and the fundraising, monitoring and reporting of the project, while UNACHO will be responsible for implementing and the day-to-day work of the project [22].

The presented article is the final product of a research year in collaboration with Dialogos, ICOHEP, Bispebjerg Hospital and Copenhagen University. The research year takes basis in gathering of the

―Pesticide, Health and Environment, Uganda. Project‖ baseline and has consisted of writing a project description (appendix 1), typing of the questionnaire (appendix 2), gathering of data, typing of data, analysis of data and writing an article. By agreement with Copenhagen University, the article will account as a thesis (appendix 3).

Jane Frølund (JF), who is a member of ICOEPH and connected to Copenhagen University, is the main supervisor of this thesis. JF is located at Bispebjerg Hospital Work and Occupational Medicine Department, where I have been seated when not in Uganda. Erik Jørs (EJ), who is the secondary supervisor of the thesis, is located at Odense University Hospital. JF was mainly supervising before and after the data gathering in Uganda, while EJ was supervising during data gathering in Uganda.

Deo Sekimbi (DS), who is the project coordinator in Uganda, was also present during the data gathering, and will be responsible for the future coordination of the project in Uganda. At the same time of the baseline gathering observational studies were done, concerning the use of pesticides and protective measures.








Over the past years there has been an increase in the use of pesticides in developing countries, many of them being listed as extremely and highly hazardous. Improper use of pesticides can cause acute pesticide poisoning. A cross-sectional study was conducted using a standardized questionnaire. 319 small scale farmers in the districts of Pallisa and Wakiso in Uganda were interviewed. The study showed that the main pesticides used belonged to WHO class II pesticides, and that a majority of the farmers did not use appropriate personal protective equipment (PPE). Also many farmers lacked adequate knowledge concerning the colour coding of the pesticides.

There was no significant association between the number of times sprayed with pesticides and self reported pesticide symptoms. However there was a significant association between using their mouth to unblock the nozzle of the knapsack sprayer (OR 2,13 with a 95% CI 1,09 – 4,18) when spraying with class II pesticides within the last year.

These findings suggest that an effort must be made to upgrade the farmers’ knowledge so that they keep the most dangerous pesticides off the market. Additionally attention should be called to class III and U pesticides, helping the farmers to understand the classification and labelling of the pesticides, and future interventions also must focus on not using their mouth to unblock the nozzle.

Keywords: pesticides, poisoning, small scale farmers, health, knowledge, developing country.




The balance between population increase and sufficient food production is one of the most important challenges in many African countries, including Uganda [23]. The use of pesticides is an effective method to protect crops from being damaged and to improve yields [24]. Over the past years there has been an increase in the use of pesticides in developing countries, and the developing countries now account for about 20% of the worlds expenditure [25]. However, improper use of pesticides can cause direct human poisoning, accumulate as residues in food and environment and lead to the development of resistance in pests [26, 27].

Approximately 300.000 workers die worldwide from pesticide exposure every year with the majority of deaths occurring in developing countries [2, 5]. The main part of these deaths is due to self-poisoning. In addition to this comes 3.000.000 cases of acute pesticide poisoning every year [16].

The Food and Agriculture Organisation of the United Nations (FAO) has tried to control the use of pesticides with its code of conduct [5]. For instance, FAO recommend governments in developing countries that small scale farmers should only be given access to pesticides that require little personal protective equipment [3, 12, 28, 29]. Moreover The World Health Organisation (WHO) has made an Essential Drug List (EDL) categorising the pesticides according to health hazard, going from extremely hazardous to unlikely to present acute hazards. This is a useful tool, especially for developing countries, for elimination of the most dangerous pesticides. However, many pesticides used in developing countries are still listed as extremely and highly hazardous [3, 12]; for example, Jors et. al. have documented a frequent use of the most toxic pesticides among farmers in Bolivia, who have had no introduction on how to use pesticides and protect themselves against the dangers of intoxication [13]. Also, studies in four African countries have shown use of unauthorised pesticides and a lack of advice on alternatives [20].

It is crucial that the use of pesticides is assessed to ensure that it does not harm humans or nature.

Therefore the use of pesticides in developing countries should be further investigated and clarified, to provide a guideline for governments and international organizations making appropriate policies [13, 24, 30].

Many farmers in Uganda are small scale farmers with less than a few acres per household. Often they farm without the money or the knowledge to use pesticides appropriately [19]. Incorrect dosage, incorrect timing and targeting, poorly maintained equipment, mixing with bare hands, lack of personal protective equipment (PPE) and lack of precautions when spraying may result in acute pesticide poisoning (APP) [20, 31, 32]. In the absence of appropriate handling with pesticides, not only the health of farmers, but also their families´ health is at risk [23].

Studies have shown that it is beneficial to look at the knowledge, practice and attitude towards pesticide use. Yassin et. al have made a study in the Gaza Strip pointing to the fact that even though the farmers


11 had high levels of knowledge on the health impact of pesticides they did not act according to this. It is important to emphasize that clarifying these aspects makes it easier to take action where it is needed. This will over time minimize the hazards of occupational pesticide exposure [23, 30, 31, 33].

The aim of this paper is to determine the extent and character of pesticide use by small scale farmers in Uganda, and to examine the practise and impact of protective measures and the storage of pesticides.

Furthermore it assesses how the farmers’ knowledge affects the use of pesticides and analyses the relationship and nature between use of pesticides and symptoms of acute pesticide poisoning.





This cross-sectional study constitutes the baseline of a three year intervention study of farmers´ pesticide use, health and environment in Uganda. The project is in collaboration with the Danish NGO Dialogos and the Ugandan NGO Uganda National Association of Community and Occupational Health

(UNACOH) and is funded by The Danish Ministry of Foreign Affairs.

The general objective of the intervention project is to reduce negative health effects of pesticides in humans and prevent pesticide pollution of the environment. The elements of the intervention consist of educating farmers, extension workers and pesticide dealers in integrated pest management (IPM), and by educating health care workers in prevention, diagnosis and treatment of acute and chronic pesticide poisonings. Through seminars and meetings, the project aims to help local key stakeholders to form a pesticide committee. The effect of the intervention will be assessed in 2013.



We conducted a cross-sectional study including 317 small scale farmers. The fieldwork was carried out from January to February 2011 in two different districts in Uganda: Wakiso and Pallisa. According to the research from the planning of the project Wakiso primarily grows vegetables (groundnuts, tomatoes, green pepper etc.) and Pallisa primarily produce cotton. 40-90% of the farmers were expected to use pesticides [22].

Wakiso is situated in the northern part of Uganda, approximately 20 kilometres northwest of the capital Kampala, close to Lake Victoria, with an average elevation of one kilometre above sea level. 1.310.100 people is living in Wakiso.

Being close to Lake Victoria the Wakiso district is generally very fertile.

Pallisa is situated in the eastern part of Uganda, 170 kilometres from Kampala close to the border of Kenya, also with an average elevation of one kilometre above sea level, with a population of 394.000 people.

Pallisa's climate is predominantly continental with a lot more sun and less rain. Unfortunately, the study data was gathered in Pallisa’s dry season. This affected the outcome of our analyses as the spraying is generally more frequent in the wet season due to higher pressure of insect pests, diseases and weeds.



In many African countries, farming is usually a business with all the family members engaged in the agricultural activities. Hence the whole family appears to be at risk of pesticide exposure [23]. Therefore we accepted subjects of different ages and both genders. Having enough women in the material to make


13 statistical analysis was a priority in the gathering of the study population, since the data on women and pesticides are currently very limited.

The project team, consisting of the project manager (EJ), the day to day project leader (DS), the research assistant (AH) and local assistants, visited and established contact to the local authorities in the two districts before starting the data collection. During these meetings, time and dates of the interviews were scheduled.

In each district a mid-level manager was connected to the project team. He or she was in charge of making contact with the local farmers and of making arrangements for interviewing. Both farmers organized in a farmers´ group and farmers outside a group were included in the study. At most times all members of a farmer group would gather at the group leader’s house or at a village hall. At other times they would gather in smaller numbers at different more convenient places, like member homes or in the field. Meetings with farmers who were not a member of a farmer group would also be arranged by the mid-level manager, these interviews were carried out in the home or in their field.

The interviewers were dropped off at the interviewing spot in the morning, picked up for lunch and then again going out for more interviews in the afternoon. Several places were only accessible by foot or in a four wheel drive truck and therefore transportation was a time-consuming factor.

The total number of small scale farmers´ in the visited areas is not available. Therefore it is not possible to calculate how big a part the 317 farmers represent or how many chose not to be part of the study.



All participants were interviewed individually with the use of a standardized questionnaire. The questionnaire has been used successfully in other studies in Colombia and Bolivia. It was originally written in Spanish but translated into English [13, 34].

Most questions were one of two types; either yes/no questions, offering a dichotomous choice, or multiple choice questions, offering several fixed alternatives. In addition to demographics and crop production, the questionnaire asked about type and amount of pesticides used, knowledge of pesticides, attitude and practice during the mixing, application and storage of pesticides and toxicity symptoms.

A pre-test was carried out with 15 farmers in both Pallisa and Wakiso (not included in the sample) to modify the questionnaire. The modification primarily included rephrasing to more understandable English and focusing on more information about the training and handling of pesticides.

At each district 8-12 people interviewed the farmers. The interviewers were young Ugandan students or recently graduated. The people interviewing in Pallisa were not the same as in Wakiso except for the project team which was involved in both districts.

Each question was translated on the fly by the interviewer from English into the local language during the interview. Consequently there might have been small differences in the translation. To minimise this and other biases there was a two day introduction to the questionnaire before starting the interviews. An


14 important part of this training was to secure that the interviewers understood the meaning of the

questions, and to discuss possible ways to translate each question from English to the local languages.

The interviewers were also instructed on when only to choose one fixed answer and when it was possible to tick multiple answers and when to read the fixed answers aloud and when not to. An additional part of the training was that the project team or public health and agronomist teachers at Makerere University reviewed the first couple of responses together with each interviewer, in an effort to minimise


All interviews were conducted face to face, and a trained interviewer would take approximately 30 minutes to complete an interview.



Exposure to pesticides may be by inhalation of vapour or direct dermal or oral contact. The main exposure measure covering these routes of exposure were self-reported number of times sprayed.

There were two different time points measuring this exposure. The first one was number of times sprayed in the last month, and the second was number of times sprayed in the last season.

Pesticides used within the last month were divided into three groups: sprayed 1 time, sprayed 2-3 times and sprayed more than 3 times. People not spraying were left out of this part of the analysis, because they were not asked about symptoms in the last month. Pesticides used last season were divided according to the WHO classification of pesticides, making it possible to do analysis on class II, III and U pesticides.

Moreover for class II pesticides we divided the number of times spraying into tertiles; spraying 1-7 times, 8-12 times and more than 12 times, using ´not spraying´ as the reference group. Class III and U pesticides were divided dichotomously into not spraying or spraying one or more times.

When using a knapsack sprayer to distribute pesticides the nozzle sometimes blocks. The second exposure variable was whether the small scale farmer would use his mouth to blow or suck in order to unclog the nozzle. This variable was divided dichotomous (yes/no).



The questionnaire included three self-reported outcome measures in relation to pesticide poisoning. As the first measure each farmer was asked if he or she had had any symptoms immediately after pesticide spraying in the last year, spontaneously mentioning all the symptoms they could recall (―spontaneous last year‖). Secondly the farmers were asked in the same way if they had experienced any symptoms

immediately after spraying pesticides within the last month (―spontaneous last month‖). Finally, as the third measure, the farmers were once again asked if he or she had had any symptoms the last month, but now 18 different symptoms were read aloud, allowing for the farmer to agree or disagree with each symptom (―asked the last month‖). The reason for making both a ―spontaneous‖ and an ―asked‖ outcome measure was to eliminate possible recall bias that could happen in a cross-sectional study.


15 Each symptom was aggregated into a dichotomous variable, with 0-1 symptom coded as 0 and more than one symptom coded as 1. This was a choice made because many of the symptoms spontaneous and asked are frequent in other diseases. For all three outcome measures only symptoms potentially related to class II and III pesticides were included [35].



The following set of explanatory and potential confounder variables were included in all analyses:

District (Wakiso/ Pallisa), age (continuous), gender (female/male), marital status (yes/no), farmer group (yes/no), educational level (no education/ primary school/>primary school), PPE (yes/no) and precautions (1-2/>2). Age was used as a continuous variable. We used both age and age squared in the analyses.

One might argue that it would have been better not to keep all the potential confounders in the analyses, but these factors have previously shown to have an effect on pesticide symptoms and were therefore kept in the analyses [13, 33, 36].



Descriptive statistics with means, standard deviation (SD) and range were used. The association between exposure (number of times sprayed in previous month / season) and health outcome were analyzed using logistic regression. Both crude and adjusted odds ratios are presented. The adjusted logistic regression analyses included district, age and age squared, gender, marital status, farmers group, educational level, PPE and precautions.

Sensitivity analyses were performed with different cut points for number of times sprayed with pesticides and number of symptoms.

Earlier analyses have shown an association between gender and number of times spraying with pesticides [37]. Therefore interactions were calculated for gender, with both the type of interaction and the main effects in the analyses. Also there might be an association between the exposure variable and age so interactions were also calculated for this variable [38]. As differences in the two districts turned out to be significant, analyses with stratification was also carried out.



Because data was gathered by interviews, missing variables were kept to a minimum, less than 3% on average. In the few cases of missing values, most of these are related to interviewers being unable to translate the question, respondents not understanding the question or typing errors.





The Helsinki declaration of ethical principles for medical research were followed [39]. The study was approved by the local leaders in each district, before starting the data collection. It was voluntary to participate in the study and the participants were encouraged, but not forced, to be part of the interview.

All respondents were explained the purpose of the study, and after informed oral consent, written consent was obtained from each participant. Illiterates provided a thumb print as an indication of their consent.





The total number of responses was 317. Tables 1 and 2 provide demographic details of the participants.

The majority of the farmers were males (61%), a total of 155 (49%) were from Wakiso and 161 (51%) were from Pallisa. The average age was 42 years, and 216 (68%) of the farmers were organised in farmers groups.

Analysis of the educational level showed that 42 (13%) had no education, 143 (45%) had finished primary school and 116 (37%) had an education level of secondary school or above. The range of land used for crops was from 0,25 – 38 acres. This measure is self reported, and may be quite imprecise since many of the farmers were unsure of how much an acre was. However, with a mean of 4,15 acre, the presumption that most farms are small scale is being confirmed.



Figure 1 shows the crops grown in the two districts, on which the farmers use pesticides. The Figure illustrates that different crops are grown in the two districts. In Wakiso there is a greater diversity of what is being grown. The main crops grown in Wakiso are tomatoes, nakati (a kind of eggplant), cabbage and green pepper. In Pallisa the main crops are cotton, green peas and cowpeas. The figure also shows that many of the farmers grow more than one crop.



A total of 306 (96%) interviewed farmers were using pesticides and had been doing so with a mean average of 17,5 years.

The 14 self-reported pesticides used by the farmers in the last month are shown according to the WHO classification, and chemical family in Table 3.

No pesticides were registered as extremely hazardous (Ia) or highly hazardous (Ib). Moderately hazardous (class II) were the most frequently used pesticides according to the questionnaire with cypermethrin and cypermethrin-profenofos being used by the largest number of farmers. To some degree slightly hazardous pesticides (class III) and pesticides unlikely to present any harm in normal use (class U) were used, mainly Glyphosphate and Mancozeb [12]. Figure 2 shows the number of times the farmers sprayed with the different pesticides within the last season in Wakiso and Pallisa. Unfortunately it is not possible to say anything about the amount of pesticides used when spraying. However it is possible to say that pesticides were sprayed more often in Pallisa than Wakiso in the last season.





The prevalence of self-reported symptoms is shown in Figure 3. The symptoms shown are divided into the three outcome categories: Symptoms immediately after spraying in the last year (―spontaneous last year‖), symptoms immediately after spraying in the last month (―spontaneous last month‖) and symptoms immediately after spraying in the last month (―asked last month‖). Skin irritation, headache, extreme tiredness, blurred vision and dizziness are the most commonly reported symptoms. The table shows - not surprisingly - a tendency to more symptoms being reported in the last year and when asked.



Levels of knowledge among the farmers are described in Table 4. 289 (92%) of the farmers think pesticides can have a negative effect on their health, 276 (90%) know that the pesticide containers have marks showing the toxicity and 228 (74%) say that they are able to read and understand these

instructions. Despite these facts only 69 (22%) know that red color indicates the most dangerous pesticides. Even more farmers (64%) do not know which sign marks the least dangerous pesticides.

Approximately one third (31%) of the farmers have had training on how to use and handle pesticides.



Table 5 illustrates the practice and attitude for small scale farmers towards pesticides.

The majority of the farmers (93%) use a knapsack sprayer to distribute and mix the pesticides. More than 80% of the small scale farmers take less than 3 hours to spray their field. 22% of the males and 12% of the females take more than three hours to spray their field.

Questions relating to personal protective equipment and precautions after using pesticides show that a high percentage (73%) use ordinary clothing when spraying. The most commonly used PPE were boots (51%), followed by long-sleeved t-shirts (24%). Most of the farmers take precautions after spraying pesticides, but only 80 (26%) take precautions after mixing pesticides. More than one third of the farmers (39%) mixed several pesticides in one mixture. A total of 170 (56%) farmers stored the pesticides inside the house, 39 (13%) stored them outside the house, 72 (23%) in a storehouse and 17 (5%) stored them in the field.



To clarify the association between self-reported symptoms and pesticide usage, logistic regression analyses were conducted. Table 6 lists the association between spontaneously reported and asked

symptoms the previous month and number of times sprayed with a pesticide the last month. The analyses were conducted on 171 of the 309 participants (62 from Pallisa and 109 from Wakiso). The crude odds ratios showed no significant association between numbers of times sprayed and symptoms of pesticide


19 poisoning. There was an increased crude OR of 2,45 (95% CI of 1,12 - 5,36) for spontaneously self- reported pesticide symptoms in Pallisa. After adjusting for potential confounders there was still no association between the number of times sprayed and self-reported pesticide symptoms, and the potential confounder district became non-significant.

Precautions (continuous) showed a significant association with an OR of 1,46 (95% CI 1,02-2,09) for asked symptoms in the last month.

Table 7 shows the association between symptoms immediately after spraying the last year for class II, class III and class U pesticides. These analyses include the whole population of 317 participants. The analyses show that there is no significant association between self-reported symptoms and the amount of times sprayed with each pesticide class. However, the results show that district is a potential confounder with and an increased OR of 2,56 for Pallisa (95% CI 1,34 – 5,24) when spraying with class II pesticides.

The same tendencies are shown for class III and U pesticides, decreasing when using less dangerous pesticides.

Gender and farmers group were shown also to have a significant association as confounders, increasing the risk of pesticide poisoning if you are in a farmers´ group (class II: OR = 2,22, 95% CI = 1,18 – 4,19) (class III: OR 2,17, 95%. CI 1,16 – 4,08) (class U: OR 2,17, 95% CI 1,15 – 4,06 ) and decreasing the risk when being a woman (class II: OR 0,49, 95% CI = 0,26 – 0,92; class III: OR 0,49. 95% CI 0,26 – 0,89; class U: OR 0,49. 95% CI = 0,27 – 0,90).

Again the analysis show that those taking more precautions (continuous) have a significantly higher risk of more than 1 symptom with an 95% OR of 1,32 and a CI 1,02 – 1,79 for class II pesticides (class III:

OR 1,34, 95% CI 1,03 – 1,75; class U: OR 1,36, 95% CI 1,04 – 1,78) than those not taking precautions.

Since several of the previous analyses showed that there was a significant difference between the two districts we decided to make logistic regression analyses stratified on the two districts for class II pesticides (Table 8). However, this did not change the association between the number of times sprayed and symptoms or the unexpected directions of the ORs in some of the confounder variables. Again, a significant protective effect was shown for females (OR = 0,34, 95% CI = 0,13 – 0,84) and an increased risk when taking precautions (OR = 1,75, 95% CI = 1,17 – 2,63) for Pallisa. Significant associations were found for spraying 1-7 times (OR= 0,17, 95% CI = 0,03 – 0,99) compared to not spraying and farmers group (OR = 3,6, 95% CI = 1,23 – 10,45) was found in Wakiso.

When testing for interaction there were no significant findings. Also when changing the cut points for number of times sprayed and number of symptoms this did not influence the odds ratios significantly. As well as age squared did not have any significant effect on the outcome.





To look at the symptoms in another perspective we divided them into four categories: Neurological symptoms, abdominal symptoms, skin symptoms and respiration symptoms. Doing the analysis again for each symptom group controlling for the confounders none of the groups had significant values, neither in the last month or in the last year. Also we did not find any significant values when we examined the two most reported pesticide poisoning symptoms, skin irritation and headache, one at a time.

Analysis performed with use of mouth to unblock the nozzle (either blowing or sucking) as the exposure variable showing a significantly higher risk of getting acute pesticide poisoning within the last year with a crude OR of 2,46 (95% CI 1,36 -4,33). After adjusting for the potential confounders keeping number of times sprayed in the analysis the OR for class II pesticides was 2,13 with a 95% CI 1,09 – 4,18. When calculation the adjusted OR the last month spontaneous and asked it is still elevated being 1,32 (0,45 – 3,88) and 1,56 (0,53 – 4,55) respectively, but not significant.




Our findings show that class II pesticides, mainly cypermethrin and cypermethrin-profenofos, are the most frequently used pesticides for small scale farmers in Wakiso and Pallisa, Uganda.

This is an important finding, as other studies have shown extended use of class I pesticides in developing countries. In a cross sectional study by Jors et al. in Bolivia for small scale farmers, it was shown that one of the frequently used pesticides is Methamidophos, which is classified as highly hazardous class Ib [13].

Also in Vietnam there has been an increased use of class I pesticides even though many of them are banned [40]. However a study made by Ngowi et. al. in Northern Tanzania, close to the border of Uganda, has shown a low quantity of class I pesticides; also a study made in Ghana indicates that small scale farmers

mainly used class II and III pesticides [26, 36]. These studies suggest that African small scale farmers are not as exposed to class I pesticides as Asian and Latin American farmers. A study made in Kenya found that mainly large scale farmers and not small scale farmers used class I pesticides [41].

Nevertheless class II pesticides are still known to have a moderate hazardous effect on humans, and there are other less dangerous alternatives [12, 29]. In addition, we expected that 40-90 % of the farmers used pesticides, but the data showed that 97% did. This supports the fact that the use of pesticides is increasing in Africa, and will probably continue to do so as long as the population increases. Effective interventions needs to be introduced to help the farmers get a sustainable relationship to pesticides [19]. Another focus of this study was to examine the practice and impact of protective measures and the storage of pesticides.

Less than one of six uses any of the four protective measures: Gloves, overalls, masks or hats. And more than half of the farmers store pesticides inside their house. This puts the environment and the health of the farmer and his family at risk [19, 20, 23, 26]

Moreover many of the farmers in Pallisa and Wakiso do not know enough about how to use and handle pesticides. As seen in other studies the small scale farmers have some knowledge of the names and effects of the pesticides they use but lack knowledge about mixing and of the color coding of pesticides [13, 23, 33]. These findings show lacking knowledge, and unhealthy practices and attitudes concerning the use of pesticides. Without adequate knowledge, practice and attitude on pesticide classification systems, application rates, inefficiency of combining pesticides, re-entry periods, mixing and storage of pesticides farmers are unable to make good crop decisions and exercise proper practices [2, 26].

Integrated Pest Management has shown to have an effect on minimizing the use and improper practice of pesticides. IPM emphasizes the importance of the growth of healthy crops and encourages natural pest controls systems. It keeps the use of pesticides to a level that is affordable for the farmers and reduces the risk to humans and the environment while still yielding the expected outcome [20, 29, 30, 42].

This study also hypothesized that there would be an association between use of pesticides and pesticide poisoning symptoms. The result of the comparison does not support this hypothesis. After adjusting for


22 gender, age, marital status, member of a farmers group, district, PPE and precautions, the OR did not show a significant association between number of times sprayed and symptoms of acute pesticide poisoning.

The lack of associations between number of times sprayed and pesticide poisoning symptoms could be due to numerous reasons.

Firstly confirming an association in a cross sectional design can easily lead to overestimation of the assumption between outcome and exposure, because of recall bias [43]. In the present study we made an effort to avoid this by making numerous outcome measures. First of all the farmers were asked to mention symptoms both within the last year and the last month, because we assumed that the last month would be less sensible of recall bias hence making it the strongest association between number of times sprayed and APP. However, because of the dry season in Pallisa, symptoms within the last year turned out to be the most reliable measure.

Secondly we assumed that we could remove some reporting bias by having the farmers spontaneously mention symptoms in relation to pesticides, and then afterwards asking about specific symptoms both related and un-related to pesticide poisoning. However we did not encounter this kind of bias. The main symptoms reported were skin irritation, headache, extreme tiredness, blurred vision and dizziness which are consistent with other studies [44]. Many of these symptoms could be due to other factors like hot climate, long exposure to sunlight or other diseases [26]. This might also affect the outcome as the farmer might be exposed to these factors simultaneously. We could have eliminated some of this by focusing more on physical signs, making health care personal observe the farmers. Another possible way to obtain better information in relation to symptoms could be to ask the farmer to keep a diary and write down symptoms occurring up to 48 hours after spraying; this could eliminate some recall bias [10]. S. Dasgupta et al. calls attention to the point that self-reported symptoms is a weak indicator for pesticide poisoning, and recommend AChE testing instead [40]. However AChE can be insufficient as there is a big variation within people and would make the study much more costly [15].

It is also possible that the amount of pesticide sprayed was insufficient for an exposure to be detected, supported by the fact that majority of the farmers took less than three hours to spray their field and only used class II pesticides.

Thirdly conduction of the interviews might have had an influence on the missing association between number of times spraying pesticides and pesticide poisoning symptoms. Even though interviews were carried out by trained groups, and the training emphasized understanding the questionnaire, it was not possible to ensure that the translation of the questionnaire was clear and understandable, as we couldn’t fully control the translation. With up to 14 people doing the interviews it is almost impossible to secure stringency and homogeneity. By a written translation of the questionnaire into the local language we might have been able to eliminate some interview bias. Also the study population itself could encounter some bias as we didn´t know the overall number of farmers in the two districts. However it seemed like the farmers gladly participated and that they were representative of the general population in the two


23 districts and all the farmers who had the opportunity to participate did so. The only farmers not

participating were the ones who did not know about the study.

We did find a constant increased risk of getting pesticide poisoning when living in Pallisa (OR 2,7) when using class II pesticides in the last year. When stratifying in the two districts there was still no association between number of times sprayed and pesticide poisoning symptoms. The reason for the increased risk could be that the main crop grown in Pallisa is cotton, which is a high growing vegetable, and thereby the pesticides are closer to the breathing zone posing more danger. Another reason could be that Pallisa is a more remote area, not having the same access to knowledge as Wakiso.

Also male farmers seemed to have an increased risk of getting pesticide poisoning. There has been expressed concern about female farmers spraying and the need for more data [38, 45]. Therefore it was a priority in this study to interview both males and females farmers. However when it comes to spraying of pesticides, the knapsack sprayer (which was used by 93% of the farmers) is very heavy. Other studies have shown that it is mostly men carrying the knapsack sprayer, where women are more involved in transporting, weeding and harvesting [36]. If men carry the knapsack sprayer for a longer time than women, men will have a longer exposure time. This is consistent with the fact that 22% of the men, and only 12% of the women, carry the knapsack sprayer for more than three hours in this study, and could be one of the reasons for the elevated OR for men [46]. Very few studies look at both genders in relation to pesticide exposure. The number of women participating in this study is a strengthening, and may help clarify women’s exposure to pesticides, but more studies would help to clarify this relationship.

We found that farmers organized in groups had an increased risk of reporting pesticide poisoning symptoms. We were aware of these associations, since the purpose of the groups is to strengthen its members. This finding could also be caused by group members influencing each other in a negative way.

The group seems to be of significant importance to the farmers when it comes to distribution and selling of pesticides, and must therefore be taken into consideration when doing interventions. There is a lack of studies looking at how the organization of farmers in groups affects the correlation between the use of pesticides and pesticide poisoning. It would therefore be recommended that other studies take this into account.

Furthermore we looked at the exposure of blowing or sucking a clogged nozzle of the knapsack sprayer.

This analysis showed a significant increased risk of reporting pesticide poisoning symptoms within the last year, controlling for potential confounders. These results suggest that this routine performed by one fifth of the farmers should be targeted in the intervention. In the study referred to earlier by Jors et. al.

49% of the farmers would either blow or suck the nozzle of the knapsack sprayer if it clogged, but the study does not examine the association between this practice and pesticide poisoning symptoms [13].




As this study is a baseline in a three year intervention program, the present findings makes it possible to specify the coming interventions where it is really needed. The study shows that the pesticides used in Uganda are far and foremost class II pesticides and that the most dangerous pesticides are rarely found in the market. It also shows that many of the farmers do not use the proper PPE. Moreover an effort to upgrade the farmers’ knowledge about labelling and classification of pesticides must be made, enabling them to stay away from the most dangerous pesticides and raising awareness of class III and U pesticides.

No association between the number of times sprayed with pesticides and symptoms of acute pesticide poisoning was found. We found that farmers using their mouth to unblock their nozzle have an increased risk of pesticide poisoning, making this parameter important in an intervention.







Distribution on district, gender, farmers group, educational level and pesticide use of small scale farmers in Uganda.

Wakiso Pallisa %

District: N % N % N

Wakiso 155 49

Pallisa 161 51


Female 123 39 64 43 58 36

Male 190 61 87 57 102 64

Farmers´ group*:

Yes 216 68 101 66 113 70

No 101 32 53 34 48 30

Educational level:

No education 42 13 16 10 26 16

Primary School 143 45 76 49 66 41

Secondary school 112 36 54 35 57 36

University 4 1 4 3 0 0

Other tertiary 16 5 4 3 12 7

Use of pesticides

No 11 3 9 6 1 1

Yes 306 97 145 94 160 99

* Farmers´ groups are characterized by 10 – 30 farmers organizing to help each other with transportation and selling of crops to save money on distribution expenditures, but also with the purpose of exchanging knowledge on farming.






Demographic details (self-reported) on small scale farmers working with pesticides, Wakiso and Pallisa, Uganda.

n Mean Standard Deviation Range

Age 318 42 12,74 13 – 76 years

Acres of land cultivated 316 4,15 4,54 0,25 – 38 acres

Acres of rented land for small scale farmers 316 1,35 1,80 0 – 12 acres

Years of engagement in agriculture 316 22,46 13,28 0 – 69 acres

Years of utilizing pesticides 311 17,55 12,51 0 – 69 yeas






Crops, on which the small scale farmers use pesticides, grown in Wakiso and Pallisa. Only crops reported by five or more farmers are included.

0 20 40 60 80 100 120 140 160

banana bea

ns cabbage

cassava cotton

cow peas groundnuts

green peas maize

millet nakati

orange potatoes

salad soya beans

spinach sweet

potatoes tomato

chillies eggplant

green pepper

number of farmers

Pallisa Wakiso






Classification of pesticides used by small scale farmers, in Wakiso and Pallisa, Uganda. January 2011

Pesticide Number of farmers Pallisa Wakiso Toxicological class by WHO Chemical class

Glyphosate 14 1 13 III Phosphonomethyl

2,4 D 2 0 2 II Phenoxy-carboxylic-acid

Paraquat 2 0 2 II Bipyridylium

Cypermethrin-profenofos 47 13 34 II Pyrethroid

Cypermethrin 52 24 28 II Pyrethroid

Endosulfan 1 0 1 II Organochlorine

Dimethoate 16 6 10 II Organophosphate

Malathion 1 1 0 III Organophosphate

Fenvalerate 1 1 0 II Pyrethroid

Alpha-cypermethrin 1 0 1 II Pyrethroid

Mancozeb 19 2 17 U Dithiocarbamate

Lamda cyhalothrin 11 6 5 II Pyrethroid

DDT 1 1 0 II Organochlorine

Dimethylcyclopropanecarboxylic 1 1 0 II Unclassified

Unknown 28 8 20






Pesticide use from January 2011, previous season.

0 50 100 150 200 250

Glyphosate 2,4 D

Paraquat Ametryne


ermethrin-profenofos Cyp

ermethrin Dichlorvos

Endosulfan Dimethoate

Malathion Fenvalerate Alpha-cypermethrin

Mancozeb Butanil

Lamda cyh alothrin

Pyrethroid DDT

Dimethylcyclopropanecarboxylic Unknown

Number of times sprayed

Pallisa Wakiso






Symptoms relevant for class II and III pestecides. January 2011 and january 2010 – january 2011.

0 10 20 30 40 50 60 70 80 90

Nausea Blurred vision

Dizziness Saliva


Skin irritation Muscular weakness


Respiratory difficulties Extreme tiredness

Vomiting Abdominal pain

Loss of appetite Lack of coordination

Excessive sweating

Number of farmers

Spontaneous symptoms January 2011.

Asked symptoms january 2011.

Spontaneous symptoms January 2010 - 2011.






Knowledge on pesticide handling and toxicity.

All Wakiso Pallisa

n % n % N %

Have you ever had any training on how to use and handle pesticides

No 213 69 97 67 114 71

Yes 96 31 50 34 60 29

Do you know of any alternatives to pesticides?

No 183 58 90 59 92 57

Yes 132 42 63 41 68 43

Do you think pesticides can have a negative effect on your health?

No 7 2 1 1 6 4

Yes 289 92 144 95 143 89

don’t know 18 6 6 4 12 12

Can you read and understand instructions on the pesticide containers?

No 70 23 27 18 43 27

Yes 228 74 114 78 113 71

Do the pesticide containers have any signs marking their toxicity

No 16 5 9 6 7 4

Yes 276 90 136 93 139 87

Sometimes 3 1 1 1 1 1

Don’t know 12 4 12 8

Which sign marks the most dangerous pesticide?

I don’t know 122 40 75 51 47 30

Blue color coding 5 2 0 0 5 3

Red color coding 69 22 23 16 46 29

Yellow color coding 23 8 5 3 18 11

Green color coding 7 2 3 2 4 3

Skull and bones pictorials 75 24 42 29 31 20

The smell indicates the danger 70 23 22 15 48 30

Which sign marks the least dangerous pesticides?

I don’t know 196 64 115 78 80 51

Blue color coding 6 2 1 1 4 3

Red color coding 9 3 3 2 6 4

Yellow color coding 13 4 9 6 4 3

Green color coding 32 10 6 4 26 16

Skull and bones pictorials 8 3 4 3 4 3

The smell indicates the danger 50 16 11 7 39 25