Commercialization of horticulture farming, expansion of farms, and the practice of monoculture favor the proliferation of pests, which in turn increases the need for pesticides. Increased exposure to pesticides is associated with inadequate knowledge on the hazardous nature of pesticides, poor hygiene practices, lack of availability of washing facilities, and insufficient adherence to precautionary instructions on pesticide labels. Mitigating the risks posed by pesticides is considered a less compelling interest than alleviating poverty. Women working in horticulture in Tanzania usually have low levels of education and income and lack decision-making power even on matters relating to their own health. This contributes to pesticide exposure and other health challenges. Because of multiple factors, some of which act as study confounders, few studies on exposure to pesticides and health effects have been conducted among women. This review identified factors that contribute to the increased health effects among women working in the horticultural industry and how these effects relate to pesticide exposure.
The number of women in agricultural employment is increasing worldwide; women now account for about 43% of the total workforce in agriculture.1 Approximately, 80% of economically active women in sub-Saharan Africa are working in the agriculture sector.2 Similar to women in other developing countries, women in Tanzania engage actively in horticulture. Horticulture is fruit, vegetable, and ornamental agriculture. Women account for 65% to 70% of the horticultural labor force3 and thus make a significant contribution to the national economy. There are patterns in men’s and women’s agricultural tasks. Weeding and postharvest processing are considered women’s work no matter what the crop is. Men are largely responsible for cash crop farming and income-generating activities.4
Horticulture is the fastest-growing subsector of the Tanzanian economy, with an estimated growth rate between 6% and 10% per annum.3 It is mainly practiced by small-scale farmers for local markets and large-scale farmers for export markets. In 2015, the subsector is reported to have contributed about US $0.6 billion to the agricultural sector, which was almost half of what the entire agricultural sector contributed to the economy.5 Thus, horticulture has the potential to become one of the main sources of foreign exchange earnings for Tanzania. The main production areas include the southern highlands, the northern corridor, and the coastal zone. More than 85% of commercial horticultural investment is concentrated in northern Tanzania.6
Although horticulture provides food security to families and employment opportunities, especially to women, occupational health issues for women working in horticulture are not adequately documented. Much effort is put into promoting the use of pesticides to boost productivity and less effort into protecting health and the environment. Thus, women farmers and other women farmworkers are frequently exposed directly when working as pesticide applicators or indirectly during harvesting, planting, and soil preparation. They are at a greater risk of accumulated exposure because of long working hours from an early age and multiple exposures at work and in domestic settings.7 This exposure to pesticides during work is in addition to other forms of exposure, from residues in food and water to air pollution, experienced by the general population. Washing pesticide-contaminated clothes and reusing of empty containers, 2 tasks traditionally done by women, are further causes of exposure. Consequently, women horticultural workers may suffer adverse health effects.89-10 Also, women have a unique susceptibility to pesticides because of their physiological characteristics, lifestyle, and behavior.10
To support development of horticulture, approximately 5.6 billion pounds of pesticides are applied worldwide annually.11 It is estimated that 81% of pesticides used in Tanzania are applied to control pests and disease in the agriculture and livestock sectors.12 Exposure to pesticides has been reported to cause adverse health effects, and great numbers of people have been affected globally.1314-15 Annual severe pesticide poisoning cases amount to 3 million worldwide16; 25 million symptomatic occupational pesticide poisonings are said to occur each year among agricultural workers in developing countries.17 Increased symptoms of respiratory and skin sensitization, malaise, vomiting, nausea, diarrhea, excessive sweating, abdominal pain, and excessive salivation have been reported as a result of pesticide exposure.18192021-22 However, many studies are conducted mainly among the male population.23242526-27 In Tanzania, where men are more involved in pesticide application than women, more occupational cases would be expected in men than women.28 However, as has been shown by a study conducted in South Africa,29 women’s occupational health risks in the developing world can be grossly underestimated.
There are various laws, rules, and regulations on occupational health and safety formulated and implemented under different ministries, departments, and agencies in Tanzania. These laws and guidelines do not adequately address what is stipulated in regional or international requirements.9 Occupational safety and health law in the country covers only formal economic sectors. Few workers in the formal sectors use occupational health services and even fewer in informal sectors such as agriculture. Moreover, farmers are not covered by the workers’ compensation law of 2008, as they do not have formal employment.30 Women who work in horticulture receive care through primary health care services.
Understanding pesticide exposure among workers is essential for drawing firm conclusions about its health effects. This review identifies factors that contribute to the increased health effects among women working in the horticultural industry and how those factors relate to exposure to pesticides in Tanzania.
Pesticide Use in Horticulture
In response to huge demand for Tanzanian agricultural products, there has been a great increase in horticultural production for both export and domestic use that has led to intensified cultivation, a reduction in the use of traditional methods of pest management, and an increase in the use of synthetic pesticides.31 The main horticultural crops are fruits, vegetables, flowers, and spices (see Table 1), which are grown in 16 of the 24 regions of mainland Tanzania (see map, Figure 1). Pests and diseases have been the limiting factors in the horticultural development in the country. Historically, crops were grown for subsistence by smallholder farmers who practiced crop rotation and intercropping that put a check on pest populations.32 However, recent developments have resulted in monoculture and thus an increased pest population. To cope with this situation, large amounts of pesticides and other agrochemicals are used to manage pests and ensure the cultivation of high-quality products. A study conducted by Barraza et al33 on banana plantations in Costa Rica found that large-scale monoculture was perceived as one of the most important problems leading to pesticide risks.
Table 1.
Horticulture crops grown in production regions, Tanzania.
To meet the market demand for quality horticultural crops, farmers use various pesticides (Table 2).34353637383940414243444546474849505152-53 Lekei et al54 identified a total of 1182 pesticide products registered in Tanzania, representing a broad variety of active ingredients. Arusha region is known to be leading in pesticide trading and utilization in Tanzania because of intensification of horticulture.5556-57 In 2003, Ngowi et al58 reported the use of 41 different pesticides in northern Tanzania, including class IA (extremely hazardous) and IB (highly hazardous) pesticides. These pesticides are known to be hazardous to humans. The report also showed that even though they did not spray pesticides, women were exposed during pruning, grading, and general cleaning on flower farms. Also, in a study set in Kenya conducted by Tsimbiri et al,18 women who were mainly engaged in weeding, planting, and harvesting reported the highest proportion of symptoms potentially related to pesticide exposure.
Table 2.
Pesticides used in horticulture in northern Tanzania.
Pesticide regulations in Tanzania control imports, distribution, and sales, allowing pesticides to be used that are considered to be less harmful to end users. Most toxic and persistent pesticides are either banned or restricted in use, even though unregistered pesticides are found on the market. Inadequately staffed border-crossing points enable infiltration of substandard and unregistered pesticides into the country. Pesticide formulations are distributed by licensed pesticide retailers; however, unlicensed vendors also exist due to illegal trades and porous borders. To control this, pesticide retailers in the country are inspected by the Tropical Pesticide Research Institute to discourage them from selling unregistered products. However, due to geographical distance and inadequate funds to support travel for inspection, pesticide retailers in some regions are not regularly inspected. As a result, unregistered products become widespread in these areas.54 As described by London et al,59 liberalization of trade policy in Tanzania resulted in large increases in pesticide imports and altered the patterns of pesticide supply and distribution, with increases in the involvement of private retailers 80-fold from 1988 to 1997. The increase in retailers greatly outpaced the expansion of control facilities.
Among preventive measures for exposure are hazard warnings and general information posted on pesticide labels. Consumer groups and international bodies such as the World Health Organization, the International Labour Organization, and the Food and Agriculture Organization put emphasis on the promotion of activities, plans, laws, and treaties to prevent the negative effects of pesticides on human health and the environment. Because women are not considered to be pesticide users, such preventive measures do not reach them. Although there are no studies in Tanzania that have characterized women’s exposures to pesticides, our personal observations indicate that women are exposed to pesticide due to ignorance of its hazard and effects. This observation is supported by Rother et al,60 who showed that a major factor exacerbating risk was a lack of knowledge about hazards and how to protect oneself and one’s family. For instance, farm residents often are not aware of or familiar with pesticides’ labels; nor are they able, in many instances, to interpret information on labels meaningfully.
Although food consumers are exposed to pesticide residues in food, women in horticulture are also exposed to pesticides that are known to cause long-term health effects. Exposure studies in Tanzania have reported the use of pesticides that are suspected or possible endocrine disruptors or possible or probable carcinogens, neurotoxicants, cholinesterase inhibitors, or irritants.6 Endosulfan, which is mainly used in cotton production in Tanzania, is listed as a moderately hazardous pesticide and is a suspected endocrine disruptor. A cohort study conducted among male schoolchildren showed that endosulfan exposure was associated with delayed sexual maturity, in particular, interference with synthesis of the male sex hormone and the development of pubic hair, testes, the penis, and serum testosterone at age-appropriate levels.61 Other persistent organochlorinated pesticides have been associated with health effects including cancer,6263-64 reproductive defects,65 and behavioral changes.66
Risk Behavior in Pesticide Use
Risk behavior, that is, lifestyle activities that places a person at increased risk of suffering a particular condition, in this case pesticide exposure, is influenced by social, economic, and cultural aspects. The need to increase the quantity and quality of horticultural produce and pressure to use pesticides exerted by pesticide dealers increases the risk of high exposure to pesticide.
Tanzanian women have fewer educational opportunities. In total, 1 in 5 women in rural areas has never attended school, and a significant number of girls drop out at all level due to pregnancy or childbirth, early marriage, illness, the illness or death of a parent or guardian, or a lack of school fees. Although women in developing countries play a central role in smallholder agriculture, they often receive less training in pesticide management than men.59,67 Women’s roles are changing under the global system of trade liberalization and market economies. From a gendered division of labor at the household level, women are shifting to self-employment, engaging in more nontraditional activities such as salons, curio shops, child-care centers, and small trading in food and clothes. Although women continue with domestic duties, with responsibilities for children and for sick or elderly family members, their agricultural activities and responsibilities have increased.59,68 Many have become wage earners, and some single parents, in particular, have felt obliged to take jobs that put their health at risk. In 2009, about 1 out of 5 households in Tanzania was headed by a woman, and such households were among the poorest in the country.69 Women in developing countries have taken on additional agricultural roles that were initially perceived to be men’s work. These include mixing and applying pesticides in agriculture,67,70,71 which affects their health and that of their offspring. The potential for adverse pesticide-related health effects among women increases with the assumption of pesticide spraying duties.67 Women with low levels of education, low levels of pesticide use safety awareness,72 poor access to personal protective equipment, and limited training on proper use of pesticides may be at high risk of pesticide exposure and the resultant adverse health effects. Jørs et al73 showed that lower levels of education are also associated with less knowledge of pesticides and with risky behavior when pesticides are being handled.
In Tanzania, women are typically located in lower-paid, low-status work, often casually employed, with little opportunity for promotion or access to safety measures. In general, the most of the women work in the informal sector doing physically demanding unskilled manual labor. On average, they work 11 hours a day during the nonfarming season and almost 16 hours during the farming season.70,74 Moreover, they go to the field with their infants and children because they lack access to or cannot afford day care services.
Although women account for more than half the population of Tanzania, only a small proportion are involved in making decisions about agriculture, the economy, and family issues. About 40% have no decision-making power even in matters regarding their own health. The control of household income by their husbands means that women cannot act on their own. They are thus subjected to different stresses from trading, domestic, and agricultural work. In some parts of Tanzanian society, witchcraft accusations are also culturally accepted, with the health effects of pesticide exposure being attributed to bewitching or a similar traditional practice rather than a dangerous chemical. Consequently, individuals may not take the necessary measures to protect themselves from being exposed to pesticides.59
Women often work in fields while pesticides are being sprayed or enter the fields soon after spraying has taken place.70,74 Older children help with work on the farm and get exposed to pesticides as well. Long working hours in contaminated fields increase the risk of exposure and associated adverse health effects. Farmers’ knowledge and perceptions about pesticide risks play an important role in determining the extent of their exposure to pesticides.75 However, given that higher risk perceptions and greater knowledge about the associated risk do not always translate into closer adherence to precautionary advice, the relationship between risk perception and behavior may not be direct. Factors such as economic and employment pressures, as well as pressures related to peer group influences, may also influence risk-related behaviors. As a consequence, many workers and operators do not adopt protective practices nor use protective equipment.76 Women do not perceive the pesticide risk because they rarely handle pesticides directly; hence, they have no protection. Women also store pesticides nearer the home, particularly in the kitchen and bedroom because they have more control over these spaces than the field. They therefore risk exposing not only themselves but also their whole family.15,77
Pesticide-related education has an important role in increasing knowledge about pesticides’ risks and how to avoid exposure.78,79 As part of the intensification and commercialization of agriculture, concerns about the potential adverse impacts of pesticide use are often downplayed by pesticide dealers and agricultural extension service providers,15 whereas the benefits of pesticide use in terms of improved crop returns are overemphasized. The end users do not perceive pesticides as a risk due to competing interests linked to the need to generate income.
Failure to read labels, misuse of pesticides, poor knowledge of hazards, and misconceptions about pesticide exposure all influence the perception of pesticides’ level of risk. Studies conducted in Ethiopia and Tanzania found that most farmers do not read instructions on pesticides packages because they are illiterate or are simply reluctant to take the trouble.15,75 Another study, conducted in Tanzania by Kapeleka et al,12 revealed that only 1 out of 3 commercial farm workers sometimes read instructions on pesticides containers and that just a few follow the instructions. However, many depend on their supervisors to read the instructions for them. Many farmers who work on their own farms do not read labels but rely on advice from pesticide dealers, extension workers, and neighbors. The reasons for not reading or following instructions are that the labels are in foreign languages, the user is illiterate, the label uses unknown signs and symbols, or that labels are simply illegible. Kapeleka et al12 also found that even though workers understand the poisonous nature of pesticides and their potential to harm and even kill users, most do not properly employ personal protective equipment. In places where the poverty level is high, householders give priority to basic needs, such as food, utilities, clothing, and transport, and not to the acquisition of personal protective equipment.67 Empty pesticide containers have been found to be reused, mostly by women for domestic purposes such as storing cooking oil, water, milk, flour, salt, and kerosene. Empty containers always have residues and are a source of exposure that can cause harmful effects to users.
Lack of awareness and knowledge regarding personal hygiene and the unavailability of sanitary facilities increases the risks of exposure to pesticides among both women and men. People in rural areas do not get into the habit of washing their bodies regularly, even after handling pesticides, because of the scarcity of water. Laundry, including husbands’ contaminated clothes, is usually done by women, which can be a source of pesticide exposure for them and other family members. In addition, shaking hands as a greeting behavior, the practice (among women) of carrying babies with the hands, and eating with the hands are common practices that increase the risk of pesticide cross-contamination.
Farmers tend to try to avert reduced output of high-value horticultural crops by overusing and misusing pesticides. They also tend to use pesticides (sometimes in excessive or insufficient doses) that are unregistered, obsolete, restricted, or recommended for other crops. This could be due to farmers’ lack of awareness or low-risk perception.32 Women sometimes improvise pesticide application methods using perforated containers or bunch of leaves instead of spray guns or knapsack sprayers, which seem to be too heavy and sometimes are costly. These makeshift methods of application expose women to pesticides and consequently affect their health.
As a study in the Philippines showed, the assumption that only men are involved in pesticide use and management means that women are not considered for training on pesticide hazards and do not even receive pesticide-related information. A result of this assumption is that women’s exposure to pesticides is grossly underestimated.80
Pesticide Exposure and Possible Health Effects
Studies among women on associations between occupational exposure to pesticides and health problems are scarce; one reason is that the multiple factors that contribute to female fertility disorders, a significant outcome of pesticide exposure, are difficult to assess.81
Acute studies have been able to link pesticide exposure and adverse health effects such as dizziness, muscular pain, sneezing, itching, skin burns, blisters, difficulty breathing, nausea, and sore eyes. However, the major concerns in Tanzania are chronic exposures that are linked to noncommunicable diseases, such as reproductive impairment, diabetes, hypertension, and cancer, which take a great toll on women as they continue to face barriers to health care access when they are sick. Women are especially at risk, for both biological and social reasons. Pesticides are one of the causes of ill health, but there are no studies in Tanzania that link pesticide exposure to women’s illnesses. However, studies in other countries have linked pesticide exposure to acute and chronic health effects.
In an attempt to map diseases afflicting women in horticultural regions of Tanzania, we collected data on diseases reported by women through the Tanzania Health Information Management System (HIMS) in 2015 and computed prevalence of the diseases by horticultural region (see Table 3). Among the diseases that were reported to occur most frequently were upper respiratory infections, hypertension, gynecological diseases, rheumatoid and joint diseases, pregnancy complications, skin infection, nonfungal bronchial asthma, and diabetes mellitus. All these diseases were prevalent in all horticultural production regions in the country. Other diagnoses and ill-defined symptoms were also very frequently reported. However, there was no explanation as to what constituted these categories. These findings underscore the need for a well-designed and detailed study that will address instances of pesticide use in these regions that have indicated the occurrence of health effects in humans.
Table 3.
Prevalence of certain diseases reported among women in horticultural regions of Tanzania that could be related to pesticide exposure—(presented by HIMS for OPD patients in 2015).
We also found that other diagnoses and ill-defined symptoms are prevalent in all production regions. We think that some of these could be attributable to pesticide exposure because health care providers have been shown to lack the capacity to diagnose and treat pesticide poisoning cases10,82 and would likely categorize pesticide poisoning as “other diagnoses and ill-defined symptoms.” Unfortunately, in Tanzania, the occupational health services are not yet integrated into primary health care because of limited resources. By the nature of their work, women receive treatment from primary health care providers whose clinical staff are unlikely to consider their occupations in diagnosis and treatment.9 It must also be noted that the women’s diseases data collected from HIMS have some limitations. The HIMS groups are aggregated by age on the basis of whether they are younger or older than 5 years, which makes it difficult to determine the prevalence of diseases of women who are supposed to be aged 18 years or older. Upper respiratory infection was found to be highly prevalent, but it is difficult to ascertain whether this elevated prevalence is in young girls or in adult women. It is known that the disease is very common in children. The data need to be aggregated in such a way that one could get a clear picture of the prevalence of diseases among the adult women who are the subject of this review.
When women are exposed to pesticides, their fetus or children are also exposed through transplacental transfer or breastfeeding, respectively. As a result of this exposure, a growing fetus or child may suffer adverse health effects such as neurodevelopmental disorders.83 A number of studies have reported adverse health effects on women exposed to pesticides and their offspring (see Table 4).848586878889909192-93 Pesticide exposure has been associated with menstrual cycle disturbances, reduced fertility, prolonged pregnancy, spontaneous abortion, stillbirths, and developmental defects, which may or may not be due to disruption of the female hormonal function.94 In the case of Tanzania, pregnancy complications reported among the diseases in horticultural areas could be related to pesticide exposure. Associations between working on flower farms and experiencing reproductive problems such as spontaneous abortion and prolonged pregnancy have been explored. In a study done in Ecuador, Handal and Harlow90 showed that the likelihood of a report of spontaneous abortion was 2.6 times greater among female flower farmworkers than among other women. Spontaneous abortions and irregular menstrual flow have been reported by women as common disorders due to exposure to pesticides. Bretveld et al86 studied women in the Netherlands working in flower greenhouses where large amounts of pesticides such as abamectin, imidacloprid, methiocarb, deltamethrin, and pirimicarb were routinely used. The researchers reported that the risk of spontaneous abortion among these women was increased 4-fold. Meta-analyses conducted to assess potential adverse effects on reproduction showed a pooled estimate of a 2.24-fold increase in spontaneous abortion; figures of 1.31 for birth defects and 1.49 for premature infant birth were found among women with a history of working on flower farms. A study conducted in Denmark by Jørgensen et al92 found a slightly increased risk of cryptorchidism in sons of maternal horticultural workers and farmers. It is therefore important to better understand pesticide exposure and health effects in women so that both women and their offspring can be protected.
Table 4.
Studies of the impact of pesticides on women and their offspring.
An epidemiological study conducted by McLean et al93 in New Zealand revealed an association between leukemia and pesticide exposure, particularly among women working in horticulture. In the above-cited study in Denmark conducted by Jørgensen et al, women’s occupational exposure to pesticides was associated with an increased risk that their children would develop leukemia.95 Zahm and Ward96 reported that families of farmers have increased risks of neuroblastoma, nervous system tumors, Hodgkin disease, and bone and brain cancers due to long-term exposure to pesticide and pesticide residues.
Acute and chronic neurotoxicity, lung damage, respiratory failure, asthma, and male infertility have been associated with pesticide exposure.22,97,98 Cancer,99100101-102 aplastic anemia, and blood dyscrasia have been associated with occupational exposure to pesticides. Skin effects such as contact dermatitis and allergic sensitization have been frequently observed in pesticide workers after exposure to several pesticides.18 These effects are believed to be related to the pesticides’ ability to disrupt the functions of certain hormones, enzymes, growth factors, and neurotransmitters and to induce key genes involved in metabolism of steroids and xenobiotics.103 Diseases such as skin infections, bronchial asthma, and diabetes reported in horticultural regions in Tanzania could also be pesticide related.
In the US Agricultural Health Study, wives of pesticide applicators living and/or working in an agricultural region had increased levels of thyroid disease compared with the general population.104 The increased incidence of thyroid disease in these women was thought to be linked to their exposure to various fungicides and organochlorine insecticides.105 In an area of Brazil that has been shown to be heavily contaminated with organochlorine pesticides, Freire et al106 found that there was an increased prevalence of hyperthyroidism. There were also sex-specific differences; for example, women showed higher levels of thyroid hormones.
Workers in developing countries face many work-related health problems resulting from exposure to pesticides used to control pests and diseases. Both direct and indirect health effects of pesticide exposure in humans have been documented.15,107 However, the magnitude of the environmental and health effects from pesticide use in Tanzania is not fully recognized,30 and several studies have found that women’s and children’s exposure to pesticides is often underestimated.29,80,108
Final Remarks
Horticulture in Tanzania is mainly practiced by small-scale farmers, with the most of the workers and employees being women. Horticulture has transformed from subsistence to commercial with increased use of pesticides. Women working in horticulture are highly exposed to pesticide hazards due to lack of knowledge, low-risk perception, and poverty. Thus, a sex-sensitive educational programs targeting safety awareness, proper use of pesticides, and implementation of personal protective measures would be necessary to decrease the pesticide exposure risk of women farmers.72,109 Training of practicing physicians and other health care professionals would also be necessary in implementing occupational health care at primary health care facilities in Tanzania and would improve diagnosis of diseases related to pesticide exposure.
Sex-specific data on effects of pesticide use in horticulture are limited, and women have not been the primary subjects of occupational studies historically. The link between pesticides and noncommunicable diseases in studies done in other countries has raised concern for Tanzanian women working in horticulture. Data from the HIMS do not adequately provide information that would make it possible to establish links between pesticide exposure and diseases affecting women in Tanzania. However, a number of pesticides used in horticulture in the country are suspected of causing chronic health effects, some of which have been reported by women in the regions. Therefore, we recommend that sex-specific studies be conducted to assess diseases and pesticide exposure in horticulture in Tanzania. The findings would, in turn, inform strategies at the level of public policy to reduce the burden of occupational health diseases that might be related to pesticide exposure in the horticulture sector.
Acknowledgements
The authors would like to acknowledge the Tanzania Health Information Management System (HIMS) unit of Ministry of Health, Community Development, Gender, Elderly and Children for providing data on diseases which were used in this work. These diseases were reported by women who attended outpatient department (OPD) in 2015.
REFERENCES
Notes
[1] Five peer reviewers contributed to the peer review report. Reviewers’ reports totaled 2399 words, excluding any confidential comments to the academic editor.
[2] Financial disclosure The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The Norwegian Agency for Development Cooperation provided financial support through The Norwegian Programme for Capacity Development in Higher Education and Research for Development (NORHED).
[3] Conflicts of interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
[4] Conceived the work: EJM, AVN. Conducted literature search from peer review journals and grey literatures, wrote the first draft of the manuscript and led revisions of the manuscript: EJM. Jointly developed the structure and arguments for the paper: EJM, SSK, AVN. Participated in writing, interpretation, discussion, comments on the manuscript and its revisions: EJM, AVN, SSK, SHD. Made critical revisions and approved final version of the manuscript: EJM, AVN, SSK, SHD. All authors read and agree with manuscript results and final remarks and finally approved the final manuscript.
