Health Symptoms Associated with Pesticides Exposure among Flower and Onion Pesticide Applicators in Arusha Region

Introduction: Pesticides are extensively used in agriculture to control harmful pests and prevent crop yield losses or product damage. In Tanzania several studies have been conducted on health effects of pesticides on agricultural workers. However, there are few studies on neurological health symptoms associated with pesticide exposure in flower and onion farms. Objective: The objective of this cross-sectional study was to assess health symptoms associated with pesticide exposure among flower and onion pesticide applicators in the Arusha region, Tanzania. Methods: Data on demographic variables and health symptoms associated with pesticide exposure were collected from 140 males who were employed in spraying pesticides on flower and onion farms in Arusha, Meru and Karatu districts between April and May 2017. The study participants were interviewed using a structured questionnaire with questions focusing sociodemographic characteristics, occupation, pesticide exposure, common type of pesticide used in the area and neurological symptoms experienced during and after pesticide spraying. To determine the intensity of pesticide exposure, acetylcholinesterase assay was done by using the Test-mate Model 400 device with a photometric sensor. Results: Ninety-five percent of pesticide applicators reported handling organophosphate pesticides. Body weakness was the most frequently reported neurological symptom (57.1%) followed by perspiration and headache (40.7%), poor appetite and depression (29.3%) and irritation (26.4%). About 27% of pesticide applicators had an acetylcholinesterase level below the limit value. Conclusion: A high proportion of neurological health symptoms and cholinesterase test depression was noted among pesticide applicators in both farms. There is a need to conduct further studies to ascertain causality for such high instances of neurological symptoms.

often reuse of old pesticide containers for food and water storage [6]. Several adverse health effects, such as temporary acute effects like irritation of eyes and excessive salivation may result from exposure to pesticides. Effects on the central nervous system (CNS) like restlessness, loss of memory, convulsions and coma are also common. Effects on the parasympathetic and sympathetic nervous system, such as respiratory paralysis, have been widely reported [7].
Occupational health and safety and workers' compensation laws in Tanzania cover only formal economic sectors. Large-scale horticulture, particularly flower farms, is bound by the laws to ensure health and safety of their workers. The international horticultural market under fair trade also controls the use of pesticides. Most small-scale horticultural farm activities are informal and thus do not receive occupational health services in the country but rely on primary health care. Understanding the differences in pesticide exposures and health effects among pesticide applicators in large-and small-scale farms is essential in guiding resource allocation, informing policy and control efforts.
Pesticide uses in agriculture activities expose applicators to risk factors for neurological health symptoms. Little has been done in Tanzania on neurological health symptoms and the risk factors associated with pesticide exposure to applicators. The present study was initiated to assess the neurological health symptoms and associated risk factors among the pesticide applicators. Specifically, we identified the pesticides used in flowers and onions farms. The intensity of pesticide exposure among applicators in selected farms was measured by AChE assay, self-reported neurological symptoms related to pesticide exposure and observation of personal protective measures employed during pesticide application. The study conducted interviews for symptoms related to pesticide exposure and measured whole blood cholinesterase activity to determine intensity of exposure. It also observed use of personal protective equipment.

Materials and Methods
A cross-sectional study was conducted by collecting demographic and health symptom data from 140 male pesticide applicators in flower and onion farms in Arusha, Meru and Karatu districts between April and May 2017 in the Arusha region. Multistage random sampling was used to select the study subjects from the lists of 216 contractual and 182 casual workers. The lottery method was used to select three districts among the seven in Arusha region. Two wards from each of the participating districts were randomly selected: Olorien and Olmotonyi of Arusha district, Moivaro and Mlangarini of Meru district and Barai and Mang'ola Chini of Karatu district. One village from each ward was selected, randomly generating a total of six participating villages. The systematic random sampling was used to select seven farms from six villages. Lists of pesticide applicators were solicited from farm managers and a total of 20 pesticide applicators were selected randomly from seven selected farms, generating a total of 140 study participants.
The study participants were interviewed using a structured questionnaire developed by biological monitoring of pesticide exposures [8] and adapted to the local situation including translation into Swahili language. Prior to data collection, the questionnaire was pretested among 10 pesticide applicators working in vegetables gardens in Kariakoo ward, Dar es Salaam. After pretesting, ambiguous questions were identified and adjusted accordingly. The duration for administering the questionnaire was determined.
Data collection was done by the principal investigator of the study. The investigator visited the pesticide applicators in the onion and flower farms and collected data by using a pretested and structured questionnaire via face-to-face interviews with the applicators. The questions focused on sociodemographic characteristics, occupation, pesticide exposure, common type of pesticide used in the area, the use of personal PPE and neurological symptoms experienced during and after pesticide spraying. The Q16 questionnaire contains 16 modified questions, which were used for evaluation of neurological health symptoms that were answered by either "yes" or "no" [9, 10].
The observation checklist was used to collect information on how PPE were worn; quality of PPE; hazards from pesticide spills; pesticide preparation process before spraying; storage and disposal of pesticide empty containers; and personal hygiene after spraying. Visual media collection using camera was done to collect information on PPE's uses, pesticide handling and spraying process.
Erythrocyte acetylcholinesterase level, which is indicative of exposure to cholinesterase inhibiting organophosphate and carbamate insecticides, was determined from all 140 participants. The medical laboratory scientist from Tropical Pesticide Research Institute in Tanzania carried out the blood test for AChE activities on the same day of the interview. In brief, fingers were washed with alcohol and dried for few seconds. Ten microliters of capillary blood was drawn using a finger prick sterile lancing device and placed into the assay tube. AChE erythrocyte cholinesterase reagent was then dissolved in distilled water and inserted into the analyzer. The analyzer provided the measurements of haemoglobin, the level of AChE and haemoglobin adjusted erythrocyte acetylcholinesterase activity. The AChE kit used for AChE assay is approved for field use by the World Health Organization (WHO). The WHO limit was used to identify the levels that were lower and above the limit on the cholinesterase test to pesticide applicators in onion and flower farms [11].
A paired t test was used to compare the mean of AChE levels between pesticide applicators of onion and flower farms. The test was also used to compare the number of neurological symptoms reported between the two groups.

Demographic characteristics of study participants
The demographic characteristics of the pesticide applicators in flower and onions farms are presented in Table 1.
The study participants were all males whose mean age is 30.63 ± 6.048 and 28.02 ± 7.557 years for flower and onion farms, respectively. A majority of pesticide applicators in onion farms (62.5%) were below 30 years of age and 5.4% were below 18 years. Most were casual workers (94.6%) with one third having work experience of less than a year with no training on pesticide safety or management. Almost half of the workers reported working more than eight hours per day. In flower farms 52.4% of pesticide applicators were aged between 29 and 38 years and most (95.2%) worked on a contract basis. A majority (77%) reported working between one and five hours per day.

The relationship between demographic characteristics and AChE level
The result shows those pesticide applicators who are 19-28 years of age were experience AChE test below range in both groups. More than 50% of pesticide applicators that had a primary level of education had AChE below normal range in onion and flower farms, and a high proportion of those who worked one to five years had AChE below the normal range. All demographic factors was not statistically significant as compared to AChE test results (p > 0.005) ( Table 2).

Common pesticides used for crops protection
Organophosphates were the most common type of pesticides used, accounting for 98%, whereas carbamates accounted for only 2% (Tables 3 and 4). In flower farms, 75% of pesticides belonged to the organochlorine group, 25% were pyrethroid. Eighty-one percent of pesticides used in onion farms belong to organochlorine and 19% were pyrethroids, which were used for pest control. The result shows that 54.1% of pesticides were moderately hazardous (II), 21.6% slightly hazardous (III) and 24.3% were unlikely to represent any acute hazard (IV) in normal use according to WHO criteria.  Flower farms followed the procedures of pesticide management as per the direction of the manufacturer, but the interviewed pesticide applicators in onion farms revealed that 1% of stored pesticides that was easily accessible by children, 11% stored pesticide in closed containers, 54% stored pesticides in their farmhouse, 9% stored pesticides in the kitchen and 15% stored pesticides in the sleeping room.

Use of personal protective equipment and hazardous practices among pesticide applicators
Among pesticide applicators in onion farms, 83.9% do spraying only and 16.1% carry out both spraying and pesticide preparation (mixing and loading). Wearing PPE is among the behaviours mostly assumed to protect workers from pesticide exposure. In terms of protective equipment, this study shows that no pesticide applica- tors in onion farms were observed to wear any protective measures like caps, gloves, full-sleeve shirts, face masks, and shoes during mixing, loading and spraying pesticides. They put on only shirts or T-shirts, shorts or trouser and slippers or no shoes at all (Figure 1). The situation was reversed in the flower farms, where all pesticide applicators used PPE that protected them from direct exposure to pesticides (Figure 2). The common PPE used were boots, gloves, full and a half face masks and coveralls. There were several hazardous practices identified with regard to pesticide handling. It was observed that 62.7% of pesticide applicators spilled pesticides on their body when they did spraying in flower and onion farms (Figures 3 and 4). Other hazardous practices in onion farms included: mixing pesticides with bare hands (40%) or using a stick (22%), applying pesticides with bare hands (40%) or with a hand-held sprayer (40%), not wearing protective equipment or clothing while handling pesticides (40%), not washing their hands before eating, smoking or using tobacco (5%), and not bathing or changing clothes after working with pesticides (12%).  The equipment used to spray pesticide. Mobile motorized tanks with pipes and spray guns were used in flowers, whereby most of them had leakage and spilled pesticide on the ground that exposed applicators to the risk. Manual knapsack equipments were used in onions farms, which left the pesticide applicator to high exposure to pesticide because of leakages (Figure 5).
A manual knapsack was the equipment being used most frequently in onion farms for the spraying of pesticide on the field (Figure 6).
Empty pesticide containers were thrown in the field; river and home refuse collection pits in onion farms (Figure 7).      However, in flower farms, empty pesticide containers were collected into plastic bags and then transported to the distraction unit identified by TPRI then transported for distraction (Figure 8).

Neurological health symptoms experienced by pesticide applicators
Neurological symptoms were collected from all recruited study participants in both farms. The onion farmers reported more symptoms, with body weakness having the highest frequency (91.1%), followed by pain in part of the body (64.3%). The highest symptoms reported by flower farmers were excessive sweating (46.4%) followed by body weakness (34.5%) ( Table 5).

Reported neurological health symptoms in onion farms
About 39% of onion farmers and 19% of flower farmers had acetylcholinesterase levels below the normal range, whereas 60.7% from onion farms and 81% from flower farms had cholinesterase level above the limit level. The mean cholinesterase level among onion and flower farmers was 27.882 ± 3.829 U/g Hgb and 25.146 ± 3.9607 U/g Hgb, respectively. The mean average values of the AChE levels in flower and onion farm workers was 26.788 ± 4.0952 U/g Hgb with a paired T test of 1.301 and p < 0.195, which was not a statistically significant difference between the two groups. The relationship between AChE and irritation was significant in onion farms. For instance, among the pesticide applicators in onion farms who reported irritation, 20 (58.8%) had AChE levels within the normal range while 6 (27.3%) had AChE levels below the normal range (p < 0.05) ( Table 6).
Of the 24 pesticide applicators in flower farms who reported feeling abnormally tired, 20 (83.3%) had AChE levels below the normal range and 4 (28.6%) were within the normal range. Other neurological health symptoms (among the flower pesticide applicators with AChE levels below the normal range) that occur in high proportion include excessive sweating (45.6%), body weakness (36.8%) and headache (26.5%). For all reported symptoms, those with AChE levels below the normal range did not differ significantly from those with AChE level within the normal range (Table 7).

Discussion
This study demonstrates a significantly high proportion of neurological health symptoms in onion pesticide applicators when compared to pesticide applicators in flower farms, with a greater risk of pesticide exposure. This was due to lack of personal protective equipment for pesticide applicators in onion farms compared to those of flower farms, which poses a greater risk of cholinesterase inhibition and neurological health symptoms to pesticide applicators. The results of this study can be compared with the results of other, similar studies. This study aimed to assess neurological health symptoms associated with pesticide exposure among flower and onion pesticide applicators.
The study results show that more 98% of pesticides used in the study area were organophosphates and a small amount was carbamate. These results were similar to the study done in Gazoué and Savè townships, in the central republic of Benin on risk factors of pesticide poisoning and pesticide users' cholinesterase levels among farmers, which found that 72.96% of pesticide used were organophosphates and pyrethroids constituted the group of pesticides more frequently used by 88% of the farmers [15]. In addition, it is necessary to note that among the problems mentioned by pesticide applicators was a lack of knowledge about the handling of pesticides. Their presence reveals the existence of sources for the informal provision of pesticides, opening the door to increased risks of poisoning. The predominance of the organophosphates in this study showed the importance of monitoring cholinesterase activity as the main test of poisoning with pesticides.    The study provides insights into pesticide application and related health symptoms among flower and onion pesticide applicators in Arusha. A majority of pesticide applicators (75%) in the studied region suffered from one or more forms of pesticide-related health symptoms. This result was supported by the findings of the study done in Nigeria on pesticide use practices and safety issues, which reported that about 80% of both farm workers indicated that they experience discomforts such as headaches, tiredness, vomiting, nausea and skin problems (itching and skin burn) after spraying [16].
The statistically significant depletion in AChE activity clearly exhibits the exposure to organophosphate (OP) and carbamate pesticides among pesticide applicators. In the present study, the mean average of AChE level among pesticide applicators in onion farms was greater by 2.736 U/g Hgb as compared to those of flower farms, which had a mean concentration of 25.146 ± 3.9607 U/g Hgb. The findings were in agreement with a study done in Tanzania on acute health effects of organophosphorus pesticides on Tanzanian, whereby the mean was 32.0 U/g Hgb [11].
Studies have shown that the blood AChE level must be depressed to less than 20% of its normal value before symptoms of systemic poisoning appear [18]. In the present study, there was no indication of such depression, which explains the relationship between symptoms and AChE, even if the proportion of the participants with depressed numbers was observed to be higher than those who were above the limit.
The failure of farmers to use PPE during pesticide application presents potential risks to pesticide exposure. The results indicated that 100% of the onion farms' pesticide applicators in the study used no form of PPE during pesticide application; however, in flower farms the reverse was true: pesticide applicators put on full PPE during pesticide application. Forty percent of farmers apply pesticides with no PPE, while a majority of farmers (60%) put on PPE during pesticide application, of the total pesticide applicators involved in the study. Wearing or putting on full PPE during pesticide application in this study was defined as wearing a nose mask, hand rubber glove, overall, long coat, facemask and boot (rubber boot) at the time of application. Alternatively, applying pesticides without PPE connotes when a farmer uses casual farming clothes without any of the listed PPEs. The findings in this study are in line with a study done on Cambodian farmers that shows a reduction of risk of acute pesticide poisoning by 55% among more highly educated farmers who adopted extra personal protective measures [18]. The study on community-based intervention to reduce pesticide exposure to farm workers and potential take-home exposure to their families showed the importance of wearing protective gloves in reducing pesticide exposures among strawberry harvesters [19]. The study done in Ghana on farmer perceptions and pesticide use practices in vegetable production showed that pesticide poisoning occurred more often among farmers who generally did not wear protective clothing during spraying of pesticides [20]. In addition, a study of farmers who used pesticides in rural Indonesia, showed that those who wore no mask/respirator, wet clothing or short sleeves had greater skin contact with pesticides [21].
Based on sufficient evidence from this study, pesticide applicators were exposed to pesticide above the acceptable level. Those who did not use PPE were more likely to develop neurological symptoms compared to those who used PPE. Therefore, the use of PPE is unavoidable and should always be encouraged during application of pesticides.

Conclusion
Our study shows that a significant percentage of respondents from flower and onion farms are suffering from neurological symptoms that could be related to pesticide exposure. Those working in the agricultural sector requiring direct contact with pesticides but with less training for the majority of pesticide applicators, low knowledge of and lack of PPE use and high duration of exposure among pesticide applicators are more at risk from accidental pesticide poisoning, based on self-reporting (determined via questionnaire). No one, therefore, is exempted from the adverse effects of pesticides as long as these chemicals are readily available and being used in flower and onion farms in the given area of study.

Recommendation
Pesticide applicators should receive training concerning pesticide management on various onion farms as is provided to flower pesticide applicators, where pesticide applicators were aware about the risks of pesticide when being exposed to it. Also, introduction of integrated pest management practices wherever possible to reduce exposures and adverse effects arising from application of pesticides, a practice that has lost favor because of safety concerns, was important. In addition, further research is needed to ascertain causality regarding such high frequency of neurological symptoms. officers of Mbuganyekundu and Mang'ola for their assistance in obtaining respondents. We also acknowledge Mr. Tanguy Jean and Godson Mbise for their help during data collection. We also wish to acknowledge the Tropical Pesticide Research Institute (TPRI) for their support by providing reagents for AChE test.