Exposure to Occupational Hazards among Health Care Workers in Low- and Middle-Income Countries: A Scoping Review

Health care workers are exposed to numerous workplace hazards. The implementation of safety measures in high-income countries has largely mitigated these risks. However, in many low- and middle- income countries (LMICs), resources to institute safety measures are lacking, increasing the risk of occupational exposures to these hazards. The aim of this scoping review is to map and synthesize the available research on occupational hazards among health care workers in LMICs, identify research gaps and inform policy. Searches for relevant articles were conducted in five electronic databases using a broad range of search terms. The inclusion criteria were: quantitative observational or experimental studies which examined exposure to one or more occupational hazards among health care workers in a LMCI; and the article was published in English in a peer-reviewed journal. A total of 99 studies met the inclusion criteria, and data were extracted from these studies. Large proportions of health care workers in LMICs were exposed to biological hazards (bloodborne pathogens, tuberculosis), psychosocial hazards (workplace violence, burnout, job dissatisfaction), ergonomic hazards (musculoskeletal complaints), and chemical hazards (exposure to latex and antineoplastic drugs). The implementation of risk reduction strategies was suboptimal. The majority of the literature was on biological hazards (48%), and research on other hazards was limited in comparison. Occupational safety needs to become a priority public health issue to protect health care workers in LMICs. More research is needed to understand the magnitude of the problem in these countries.


Introduction
Health care workers are at potential risk of harm from exposure to numerous hazardous agents encountered in their workplace [1]. The most recent and visible example is the ongoing COVID-19 pandemic, which has showcased the vulnerability of health care workers and demonstrated the importance of ensuring their safety [2].
In addition to exposures to emerging diseases, health care workers are routinely exposed to other infectious agents such as tuberculosis, influenza, HIV, and Hepatitis B, which have been the primary focus of research and safety programs [3]. Health care workers are also exposed to various chemical hazards and agents that have been linked to long-term adverse health effects. Chemicals used in health care settings such as ethylene oxide, formaldehyde, and antineoplastic drugs have been linked to cancers and adverse reproductive outcomes [4][5][6]. Exposure to latex and cleaning and disinfecting agents has been associated with occupational asthma among health care workers [7,8]. Musculoskeletal disorders and injuries, and various psychosocial hazards such as workplace Int. J. Environ. Res. Public Health 2021, 18,2603 2 of 41 violence, stress, and burnout are other well-recognised occupational hazards among health care workers [9][10][11].
Recognising these risks, safety measures and standards to protect health care workers have been instituted in high-income countries and have largely succeeded in mitigating these hazards [12]. However, in many low-and middle-income countries (LMICs), occupational health and safety is often neglected [13]. These deficiencies in occupational health have been attributed to a lack of political commitment, insufficient resources, poor data collection systems, and weak enforcement of regulations. Occupational health research has shown that providing a safe work environment increases organizational commitment and worker retention [14]. Poor working conditions and threats to health have been reported to contribute to problems in recruitment and retention of health care workers in LMICs, augmenting the issue of health care worker shortages in these countries [15].
In order to institute any prevention and safety intervention, it is important to understand the magnitude of the problem. The majority of the literature on occupational hazards in health care workers has originated in high-income countries, and research from LMICs on this topic is reported to be limited [16]. Findings from studies conducted in high-income countries cannot be generalised to LMICs because exposures in LMICs are likely to be different from high-income countries due to differences in legislation and regulations, health care systems, work practices and the availability of control measures. There is a need to determine the scope and volume of available research conducted on this topic in LMICs and to identify any research gaps. Apart from a narrative literature review conducted in 2016, which was limited in scope and included only 46 studies, there are no other reviews available on this topic [16]. Scoping reviews have been described by Arksey and O'Malley as those which "aim to map rapidly the key concepts underpinning a research area and the main sources and types of evidence available, and can be undertaken as standalone projects in their own right, especially where an area is complex or has not been reviewed comprehensively before" [17]. A revised definition of scoping reviews was proposed by Daudt et al. as "scoping studies aim to map the literature on a particular topic or research area and provide an opportunity to identify key concepts, gaps in literature; and types and sources of evidence to inform practice, policymaking, and research" [18]. Therefore, a scoping review was conducted to map and synthesize the available research on exposure to occupational hazards among health care workers in LMICs, to identify any research gaps and to inform policy to improve the safety of health care workers.

Methods
This review was conducted according to the methodological framework for scoping reviews outlined by Arksey and O'Malley [17], Levac et al. [19], Colquhan et al. [20], and The Joanna Briggs Institute [21]. It is reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) [22]. It was guided by the research question 'What is known from the existing literature about exposure to occupational hazards among health care workers in LMICs?'

Search Strategy
The key terms relating to the research question were identified as follows: 'health care workers', 'health workers', 'health personnel', 'health professionals', 'nurses', 'doctors', 'laboratory workers' 'occupational hazards', 'occupational risks', 'occupational diseases', 'occupational health', 'occupational injuries', 'occupational accidents', 'low-and-middleincome countries', 'low-income countries', and 'developing countries'. The search strategy was developed by the research team in consultation with an academic librarian. Using these key terms and their associated mapped subject headings and MeSH terms, searches were conducted in the electronic databases MEDLINE, Scopus, CINAHL, Embase, and PsycINFO till 1 May 2020 (Table S1. Search strategy for Medline (Ovid) (date of search: 1 May 2020)). Original peer-reviewed articles in the English language were the only limits

Results
The database searches identified 609 articles, with a further 37 articles identified from a search of reference lists ( Figure 1). After removing duplicates, 330 articles were screened by titles followed by abstract examinations of 141 articles. The review of abstracts resulted in 110 articles for full-text examination, of which 99 articles met the inclusion criteria and were included in the review. The majority of the studies (34 of 99) were conducted in the Sub-Saharan African region (according to the World Bank regions), were cross-sectional in design (82), and participants were all health care workers (51) (Figure 2). Fifty one studies were conducted in district/state hospitals and primary care centres, and 48 were conducted in tertiary care centres. The included studies were published after 1991, with six studies published in the 1990s, 31  The majority of the studies (34 of 99) were conducted in the Sub-Saharan African region (according to the World Bank regions), were cross-sectional in design (82), and participants were all health care workers (51) (Figure 2). Fifty one studies were conducted in district/state hospitals and primary care centres, and 48 were conducted in tertiary care centres. The included studies were published after 1991, with six studies published in the 1990s, 31     The majority of the studies (34 of 99) were conducted in the Sub-Saharan African region (according to the World Bank regions), were cross-sectional in design (82), and participants were all health care workers (51) (Figure 2). Fifty one studies were conducted in district/state hospitals and primary care centres, and 48 were conducted in tertiary care centres . The included studies were published after 1991, with six studies published in the  1990s, 31 studies published between 2001 and 2010, and 62 studies between     Almost half the studies (47) were on biological hazards, 22 studies were on psychosocial hazards, 17 were on ergonomic hazards, and 11 were on chemical hazards (Figure 2). In addition, there were two studies that investigated the different types of occupational hazards in general. Among the studies on biological hazards, the majority (38/47) examined exposure to bloodborne pathogens and nine studies (after 2006) examined exposure to tuberculosis (Table 1). Among the studies on psychosocial hazards, 12 studies examined workplace violence and safety climate, six studies examined the prevalence of burnout and its risk factors and four studies examined work environment and job satisfaction ( Table 2). The studies on ergonomic hazards mainly investigated the prevalence of musculoskeletal complaints and their risk factors (Table 3). Among the studies on chemical hazards, six studies examined exposure to latex, and five examined exposure to antineoplastic drugs (Table 4). 13% reported accidental injuries with HIV-positive patients. The highest frequencies of injuries were among registrars. Compliance with universal precautions was suboptimal. 48% of the participants on post-exposure prophylaxis (PEP) did not complete their regimen; the side effects of PEP was reported as the main reason for discontinuation. Compliance with UP was not optimal. Compliance with UP was associated with being in the job for a longer period, knowledge of bloodborne pathogen transmission, perceiving fewer barriers to safe practice and strong commitment to workplace safety climate. Data from three years were obtained from sharps injuries, and blood and body fluid exposures reports that were reported to the Anti-retroviral therapy centre of a tertiary care hospital. 105 health care workers reported an occupational exposure to blood and body fluids. The highest frequencies were reported by interns. Needlestick injuries were the commonest type of exposure (85%), followed by mucous membrane splash (13%) and exposure on intact skin (2%). The practices that resulted in exposures were blood withdrawal (45.7%), during surgical procedures (24.7%) and disposal of sharps (23%). 60% reported being ever exposed and 43% reported exposure in the past year to blood and body fluids through accidental splashes and sharps injuries. 2.5% of the samples was positive for HBsAg and 0.42% for anti-HCV antibodies. Only 42.6% had good practices of standard precautions.

II. Tuberculosis (TB)
Lien et al. [65] 2009      Burnout was seen in 51.3% of participants. Prevalence according to subscales was: high levels of EE-66.3%, high DP scores-45% and low levels of PA-23.8%. Not being a physician and not having the right team to work with were significantly associated with burnout.

III. Work Environment and Job Satisfaction
Li et al. [   80.8% had experienced MSDs in the last 12 months. Low-back pain was the most common (61.9%). Working in a bent or twisted position, mental exhaustion and being absent from work for more than 6 months were associated with an increased risk.    Prevalence of latex sensitisation and allergy in exposed workers was 7.1% and 5.9%, respectively; and in unexposed workers it was 3.1% and 1.8%. Work-related allergy symptoms were significantly higher in exposed workers. A dose-response relationship was observed for powdered latex gloves.
Supapvanich et al. [117] 2013 Exposure to latex and latex allergy Thailand 899 nurses from three hospitals in Thailand Cross-sectional Questionnaires on respiratory and dermal symptoms that were attributed to latex gloves use.
18% reported symptoms attributable to latex gloves use. Dermal symptoms were more frequently reported, particularly itchy skin and rash. Using >15 pairs of powdered latex gloves/day, using chlorhexidine and being an operating theatre nurse were the risk factors associated dermal symptoms.
Köse et al. [118] 2014 Exposure to latex and latex sensitization Turkey 1115 health care workers from an education and research hospital in Izmir Cross-sectional Questionnaires on latex gloves use and symptoms of latex allergy. Blood was tested for latex-specific IgE levels.
Prevalence of latex sensitization was 4.2%. Latex allergy was more common in nurses.

Supapvanich et al. [119] 2014
Exposure to latex and latex sensitization Thailand 363 nurses from two tertiary hospitals in Southern Thailand

Cross-sectional
Questionnaires on use of latex gloves and symptoms related to latex use. Latex sensitization was confirmed by detecting anti-latex IgE antibodies using a solid phase immunoassay.
The prevalence of latex sensitization was 4.4%. The prevalence of latex sensitization was higher in hospitals where gloves with higher protein levels were used. Only about half of the nurses used personal protective equipment (PPE) during the administration of the drugs, and only about 5% used PPE during the administration and disposal of the drugs. Biological safety cabinets were used in all the hospitals and clinics included in the study.
Elshaer [121] 2017 Adherence to control measures used for handling of antineoplastic drugs Egypt 54 nurses and clinical pharmacists who were exposed to ADs and 54 who were not exposed, working in oncology centres in Alexandria city.

Cross-sectional
Questionnaires on adverse health effects and control measures were distributed. Nurses and clinical pharmacists who were exposed to ADs were compared to those who were not exposed.
Biological safety cabinets and ventilation devices were used by pharmacists but not by nurses. Significantly higher percentages of pharmacists reported safe handling practices and the use of PPE as compared to nurses. There was no medical surveillance program in the workplace.
Alehashem and Baniasadi [122] 2018  65.6% were exposed to 1 + biological hazard, 38.2% handled un-labelled and un-marked chemicals; and 49.5% reported laboratory equipment dangerously placed. There were a large number of other risks. Strong correlations between protective measures within individuals. Control measures reported were occupational health and safety training and supervising staff (98%), proper medical waste containers (92.6%), first aid safety equipment (36.8%), chemical hygiene plans (25%) and chemical hoods (19.1%).

Discussion
This study aimed to map and synthesize the available research on occupational hazards among health care workers in LMICs. The research conducted on this topic is quite substantial as evidenced by the 99 articles included in this review. However, half of these studies were on biological hazards, and research on the other types of hazards was minimal in comparison. The findings of this review also show that research on occupational hazards in LMICs has increased considerably in the last decade, perhaps indicating an increasing recognition of occupational health and safety of health care workers in these countries.

Bloodborne Pathogens
The majority of the literature on biological hazards was on the occupational transmission of bloodborne pathogens, such as Hepatitis B, HIV, and Hepatitis C, through needlestick/sharps injuries and splash accidents. Health care workers from LMICs are at increased risk of transmission of bloodborne pathogens because of the high population prevalence of these diseases and the fact that safety measures to reduce these risks are inadequate [126].
The prevalence of needlestick injuries was variably reported in the studies included in this review, with some studies reporting prevalence in the past year, some over the entire career and a few reporting it in the past 3 months, 6 months and 5 years. The prevalence of needlestick injuries in the past year was reported in 12 studies and showed a wide variation, ranging from 27% in a study conducted in Nigeria to 82% in a study conducted in China [28,33,35,37,40,43,[46][47][48]58,63,64]. The prevalence of needlestick injuries over the entire career was reported in nine studies and ranged from 32.4% in a study conducted in Ethiopia to 86.2% in a study from China [35,37,43,44,54,[61][62][63][64]. The incidence of needlestick injuries was reported in two studies. A study conducted in Kenya reported an incidence rate of 0.97 needlestick injuries per health care worker per year [42] and a study from Turkey reported an incidence of 2.18 exposures/person-years [59].
Various risk reduction strategies have been recommended to decrease occupational exposures to bloodborne pathogens, such as the use of standard precautions, vaccination against Hepatitis B, and post-exposure prophylaxis (PEP) for Hepatitis B and HIV [127]. Compliance with standard precautions for infection control was suboptimal as reported in a number of studies from various countries [29,30,32,33,36,38,[47][48][49][50]52,54,58,60,64,124,125]. Barriers to compliance reported were shortage of equipment, inadequate staffing, and lack of training [39]. Unsafe injection practices such as recapping of needles and reusing syringes were also prevalent [28,34,49,50,53,54]. Most of the needlestick injuries were not reported and treated [33,44,56,58]. There were seven studies that reported on Hepatitis B vaccination status. The vaccination status (completed 3 doses of vaccine) was low in most of the studies ranging from 8% to 56.1% [34,41,46,51,54,60], except for a study conducted in China (71%) [33]. Among all health care workers, vaccination rates were lowest in housekeeping personnel [34,46]. There were only three studies that examined post-exposure prophylaxis for HIV and these studies reported a low uptake of PEP by health care workers and that almost half of those who started PEP discontinued the treatment due to side effects of the drugs [27,32,42]. There were no studies reporting the use of HBV immunoglobulin for post-exposure prophylaxis for HBV infection, which could be due to its unavailability in LMICs [34].
Taken together, the findings of this review show that needlestick and splash injuries are prevalent in LMICs and risk reduction strategies to protect health care workers from these infections are suboptimal.

Tuberculosis
A systematic review on tuberculosis among health care workers in LMICs published in 2006 reported a high occupational risk of tuberculosis, with a latent tuberculosis infection (LTBI) prevalence of 54% (range 33% to 79%), an incidence of 0.5% to 14.3% per year, and an attributable risk due to nosocomial exposure from 25 to 5361 per 100,000 per year [25]. As with transmission of bloodborne infections, health care workers in LMIC are at an increased risk of exposure to tuberculosis due to high population tuberculosis rates and limited resources to institute control practices [128]. As compared to high-income countries where there are strict infection control practices to protect health care workers, even basic infection control strategies to reduce transmission in health care facilities in LMICs are lacking and tuberculosis control is mainly focused on case detection and treatment [128,129].
This present review included studies conducted after 2006, and found that occupational tuberculosis transmission is still a significant problem in LMICs. The prevalence of LTBI as reported by five studies in this review ranged from 23.6% to 76.5% when assessed using interferon-gamma release assays (IGRAs), and from 59.1% to 97.6% when assessed with tuberculin skin tests (TSTs) [65,67,68,70,73]. IGRAs are newer tests that use antigens that are more specific and hence are less likely to be affected by previous BCG vaccination status and non-tuberculosis mycobacterial infection, which are the drawbacks of TSTs [129]. In the systematic review, only one study had used IGRAs to detect LTBI prevalence. There was one study in this present review that reported the incidence rates of LTBI test conversion, a prospective study conducted in Georgia from 2009 to 2011, which reported conversion rates of 17.1 per 100 person-years for TST and 22.8 per 100 person years for IGRAs [68].
There were four studies examining active tuberculosis among health care workers in this review [66,69,71,72]. A study conducted in India reported a pulmonary tuberculosis incidence rate of 314 per 100,000 person-years among health care workers and that this was 1.86 times higher than that of the general population [66]. Another study conducted in South Africa reported a tuberculosis incidence rate of 1985 per 100,000 person-years among health care workers, which was double the incidence of tuberculosis in the general population [69]. A study conducted in China used low-dose lung CT examinations to detect active tuberculosis, and reported that the incidence and prevalence rates of active tuberculosis in health care workers were >2.8 times and >4.1 times greater than that of the general population, respectively [72].
In summary, the prevalence and incidence of LTBI in health care workers in LMICs is very high and active tuberculosis among health care workers is approximately two times higher than that of the general population.

Workplace Violence
The majority of studies on psychosocial hazards in this review were on workplace violence. Workplace violence has been reported as a significant problem in the health care sector throughout the world [10]. In this review, the prevalence of experiencing some form of violence in the workplace was high and ranged from 60.8% to 82.2% [76,78,82]. The prevalence varied depending on the specific type of violence measured (e.g., physical, verbal, sexual). Verbal abuse was the most common type of violence experienced by health care workers, with a prevalence ranging from 30.5% to 95.9% [75][76][77][78][79][80][81][83][84][85]. The prevalence of physical abuse ranged from 2.3% to 36.8% [75,76,[78][79][80][81][83][84][85] and that of sexual harassment ranged from 0.7% to 21.8% [75,76,83,84]. Patients and their families were the most commonly reported perpetrators of verbal and physical abuse, while co-workers and patients were the most commonly reported perpetrators of sexual harassment [74][75][76][77][78][79]81,85]. The risk factors for workplace violence identified in this review were working in certain high-risk areas (out-patient departments, emergency departments, operation theatres and in-patient clinics), lower safety climate levels at work, working in shifts, having heavy workloads and younger age [74,75,77,81,84].
Being a victim of workplace violence can result in a range of negative consequences (psychological, physical, emotional, social, work functioning, quality of care, and financial) [130]. Five studies included in this review reported on the consequences and associations of workplace violence [74,78,80,82,85]. Three studies reported on psychological consequences, where exposure to workplace violence was associated with anxiety, depressive symptoms and major depression, and burnout [80,82,85]. Two studies reported on work functioning consequences and found that almost half (42.9% and 45%) of the participants who experienced workplace violence reported a decline in work productivity [74,78].

Burnout
Burnout, as described by Maslach et al. [131], comprises of three dimensions: emotional exhaustion, depersonalization, and low personal accomplishment. Health care workers are known to be at an increased risk of burnout due to the inherent nature of their job which exposes them to high levels of emotional and psychological stress [11]. Burnout has been found to be associated with absenteeism, high turnover rates, low morale, and decrease in the quality of care.
Four of the six studies included in this review examined burnout among doctors (residents and anaesthesiologists) [86,88,90,91] and two studies examined it in acute and critical care nurses [87,89]. These studies reported a high prevalence of burnout. The prevalence of high levels of burnout in at least one dimension ranged from 51.3% to 80% [86,88,91]. Emotional exhaustion, depersonalization, and low personal accomplishment prevalence ranged from 39.4% to 67.7%, 38% to 68.4%, and 23.8% to 50.3%, respectively [86,88,90,91]. The work-related risk factors for burnout identified in this review were long working hours, experiencing a major stress at work, not having the right team to work with, lack of autonomy at work, and negative psychosocial work environments (as measured by perceived effort-reward imbalance). Personal risk factors were reported by only two studies and these included female gender, being single and having children [86,87]. Only one study reported on the consequences of burnout and this study found that burnout was independently associated with decreased adherence to infection control practices [89].

Work Environment and Job Satisfaction
Two studies included in this review examined job satisfaction and work environment among nurses and reported that more than fifty percent of the nurses (56.4% to 67.1%) were not satisfied with their jobs and only 31% perceived their work environment to be of high quality [93,95]. Advancement in the job, recognition, work security and a good work environment were the factors that were reported to be positively associated with job satisfaction. One study examining nurses' satisfaction with night shift work reported that only 43% of these nurses were satisfied with their night shifts, and the factors associated with the low levels of satisfaction were inadequate staffing and inadequate equipment for protection from hazards [94]. A longitudinal study conducted in China examined psychosocial work environment and intention to leave among nurses and reported a 16.3% prevalence of intention to leave and an incidence rate of 14.5% [92]. Increased emotional demands, decreased workplace commitment, decreased meaning of work and decreased job satisfaction were the factors reported to be associated with intention to leave.
The delivery of quality health care depends largely on the quality of staff delivering these services [132]. Satisfied workers are known to be more efficient and productive, thus contributing to the provision of better quality services. Job dissatisfaction, on the other hand, is associated with absenteeism and higher employee turnover rates. Providing a good work environment is a key factor in improving employee job satisfaction, organizational commitment and intention to remain [14].
In summary, the prevalence of verbal and physical abuse, and burnout were reported as being extremely high in these studies. In addition, satisfaction with work was low. These factors impact on retention of health care workers which is particularly important in the context of LMICs since these countries already face a shortage of health care workers [133].

Ergonomic Hazards
Musculoskeletal disorders are a common cause for work-related disability and absenteeism, resulting in substantial financial consequences in the form of workers' compensation and medical expenditure [134]. Health care worker are at an increased risk of musculoskeletal disorders and there is an extensive body of literature from high-income countries examining these disorders among different occupation groups within the health care sector (nurses, surgeons, physical therapists, dentists) [9,[135][136][137].
The studies on ergonomic hazards included in this review examined prevalence and risk factors of musculoskeletal disorders among health care workers. Thirteen studies examined musculoskeletal disorders using the Nordic Musculoskeletal Questionnaire, mainly among nurses (10/13 studies) [96][97][98][101][102][103][104][106][107][108]111,112], and four studies examined only low-back pain [99,100,109,110]. The prevalence of musculoskeletal complaints in at least one body site in the past twelve months was reported in 12 studies and ranged from 50.7% to 95%. The most commonly reported body site for these complaints was the lower back (35.3% to 78.2%). The prevalence reported for the other regions of the body ranged from 28% to 49.8% for the neck, 23.5% to 52.1% for the shoulders, 20.7% to 54% for the upper back and 11% to 68.7% for the knees. There was only one study that examined work-related injuries, in which 38.6% of the nurses in the study reported experiencing at least one work-related injury in the past twelve months [99].
The occupational physical risk factors for musculoskeletal complaints identified in this review were working in the same position for prolonged periods, working in a bent or twisted position, lifting and transferring patients, handling many patients, and performing repetitive tasks [102,106,112]. The occupational psychosocial risk factors for musculoskeletal complaints identified were high levels of stress, anxiety, mental exhaustion, limited support in the workplace, low decision latitude, increased workload, monotonous work, job inexperience, and absenteeism [96,98,101,104,108,111,112].
In summary, there were few studies of musculoskeletal disorders among LMIC health care workers, and they found a very high prevalence of musculoskeletal complaints in at least one body site. There was a lack of studies on work-related injuries.

Chemical Hazards
The studies on chemical hazards in this review mainly examined exposure to latex and latex allergy. Three studies examined the prevalence of latex allergy symptoms among health care workers and reported a prevalence ranging from 16% to 18% [114,115,117]. The occupational risk factors for latex allergy reported in these studies were the number of years using latex gloves, using latex gloves for >1 h per day, using >15 pairs of powdered gloves per day, longer duration of working as a health care worker, using chlorhexidine and working as an operation theatre nurse. Two studies conducted in Turkey and Thailand examining the prevalence of latex sensitization by measuring latex-specific IgE antibody levels reported a prevalence of 4.2% and 4.4%, respectively, and that the prevalence was higher in hospitals where gloves with higher protein levels were used [118,119].
The use of less allergenic alternatives such as powder-free latex gloves and nitrile gloves has been recommended to control latex exposures among health care workers [12].
A study conducted in South Africa examined the prevalence of latex allergy and sensitization after the introduction of hypoallergenic powder-free and lightly powdered latex gloves [116]. The prevalence of latex allergy and sensitization reported in this study was 5.9% and 7.1%, respectively. The authors concluded that health care workers using hypoallergenic powder-free latex gloves were at risk of developing latex sensitization and recommended that a cost-effective alternative that eliminated latex from the health care environment was required in resource poor countries.
Five studies included in this review examined exposure to antineoplastic drugs, mainly safe handling practices, and reported that adherence to control measures was suboptimal. A study conducted in Egypt reported a lack of medical surveillance programs and training, inadequate handling practices, and low usage of personal protective equipment [121]. Two studies conducted in Turkey found that only about 40% of participants used biological safety cabinets and that personal protective equipment was not used consistently [113,123]. Two studies conducted in Iran reported that antineoplastic drug handling practices were not always consistent with published recommendations [120,122].
Few studies have been conducted on the many chemical hazards in health care work. The only studies which could be found examined exposure to latex and antineoplastic drugs and there were no studies on other chemicals such as cleaning products, disinfectants and diathermy smoke.
Health care workers can also be exposed to physical hazards such as radiation, noise, and slips and falls [12]. However, this review did not identify any studies on exposure to these types of hazards from LMICs.

Implications
This scoping review has revealed that health care workers in LMICs are exposed to a wide range of occupational hazards and that risk reduction strategies and safety measures are inadequately implemented, mainly due to equipment and human resource limitations. To protect health care workers in these countries, first and foremost, occupational health and safety needs to be prioritised. This requires political commitment from governments to increase investments in occupational health and safety programs. Additionally, although development and public health agencies have promoted the importance of health care workers by including the health care workforce as an essential component of sustainable development, these agencies have focused mainly on increasing the numbers and competency of health care workers [138]. There is a need for these agencies to equally address the underlying reasons for health care workers' migration, death and illness in LMICs and to advocate for the provision of safer workplaces for health care workers in these countries.
It is encouraging that research on occupational hazards among health care workers in LMICs has increased considerably in the past decade. However, the majority of the studies in this review were cross-sectional and some of them were of low quality (quality was not an exclusion criteria). In future, larger, more well-designed and prospective studies need to be conducted to make a convincing case for prioritising occupational health and safety of health care workers in these countries. In addition, the majority of the studies were on biological hazards and there were very few studies assessing exposure to chemical hazards. This is as expected since the risks from biological hazards are more apparent in LMICs where the population rates of infectious diseases are high. However, health care workers are also routinely exposed to chemicals that have been linked to chronic diseases such as cancer and asthma. More research is required in this area from LMICs.

Strengths and Limitations of the Review
To our knowledge, this review on exposure to occupational hazards among health care workers is the most comprehensive to date. It was based on a rigorous, systematic search strategy across five large databases with no date restrictions using strict methodological inclusion criteria.
Although this review has provided an overall synopsis of occupational hazards in health care workers in LMICs, there are some limitations to this study. First, the quality of the included studies was not assessed, so the review is inclusive of all articles irrespective of their quality. Second, only articles published in English were included, which might have resulted in the omission of data published in other languages. Thirdly, there is a possibility that all data may not have been captured by the search strategy, particularly if the articles were published in journals not indexed in Medline. Lastly, this review also excluded night shift work, which is an important occupational risk for health care workers. Despite these limitations, this review provides a comprehensive overview of the hazards encountered in the workplace by health care workers in LMICs.

Conclusions
Large proportions of health care workers in LMICs are occupationally exposed to a wide range of hazards. Safety measures and risk reduction strategies in these countries are suboptimal, mainly due to resource limitations. Health care workers need to be protected from occupational hazards because these hazards have the potential to cause diseases and injuries and can adversely impact the retention of health care workers and the quality of care provided. Health care worker retention is of particular importance in LMICs since these countries already face a shortage of health care workers. Political commitment towards making occupational health and safety a priority public health issue is necessary to ensure the safety of health care workers in LMICs. Although research on occupational hazards among health care workers in these countries has increased considerably in the last decade, most of this work is on biological hazards. More research is needed on the other types of occupational hazards.

Conflicts of Interest:
The authors declare no conflict of interest.