Occupational Disease and Injury in Malaysia: A Thematic Review of Literature from 2016 to 2021

Introduction Working people are exposed to occupational hazards and are at risk of having occupational disease or injury in a rapidly industrializing country like Malaysia. This study aims to review and summarize the occupational disease and injury in Malaysia from 2016 to 2021. Methods This study used PubMed and Scopus databases to conduct a systematic literature search using a set of keywords. The selected records dated from 1 January 2016 to 8 September 2021 were extracted into the Mendeley Desktop and ATLAS.ti 8 software. Systematic screening was conducted by two independent researchers and finalized by the third researcher. Data were coded and grouped according to the themes. The results were presented as the table for descriptive analysis and cross-tabulation between the themes. Results A total of 120 records were included in this study. Under the theme of main health problems, the findings showed that mental health, infectious disease, and work-related musculoskeletal disorders are the top three problems being discussed in the literature for the working people in Malaysia. The findings also showed an increasing trend of mental health problems during pandemic COVID-19 years. In addition, hospital was the highest workplace where the occupational health problems were reported.Discussion/Conclusion. There was substantial work on the mental health problem, infectious diseases, and work-related musculoskeletal disorders as the main health problem among workers in Malaysia in the past five years. The employers must report any occupational health and injury case to the authority and prompt intervention can be initiated.


Introduction
People are exposed to occupational hazards or risks at the workplace which predisposes them to work-related injury or disease [1,2]. In 2016, almost two million deaths were attributable to occupational risks and accounted for an estimated 2.1% of all deaths and 2.7% of the disease burden worldwide [3]. Tere are nineteen identifed occupational risk factors with the most common factor being exposure to chemical hazards. Te newly added occupational risk factor is exposure to long working hours (defned as working ≥55 hours per week) which pairs with the specifc health outcomes of ischemic heart disease and stroke [4]. Te occupational risks contribute to the total burden of chronic diseases such as 37% of all cases of back pain, 16% of hearing loss, 13% of chronic obstructive pulmonary disease, 11% of asthma, 8% of injuries, 9% of lung cancer, 2% of leukaemia, and 8% of depression [5].
Occupational disease or injury which occurs directly due to the nature of work and workplace environment may reduce workers' productivity, increase sick leave, and reduce the quality of life [6]. Substantial studies reported the prevalence of occupational disease and work-related disease in their country according to certain types of diseases such as asthma and work-related musculoskeletal disorders (WRMSDs) [7,8]. Healthcare workers (HCWs) are the group who may exposed with biological hazards at the workplace as mention in previous studies [9,10]. Te International Labour Organisation (ILO) is responsible to compile the list of occupational diseases and classifying them into the disease caused by an agent (chemical, physical, biological) and the diseases according to the target organ (respiratory, skin, musculoskeletal, mental, and behavioural, occupational cancer and other diseases) [11,12]. A similar classifcation is being used by the Department of Occupational Safety and Health Malaysia (DOSH) for surveillance data in Malaysia as well as in other countries [13]. Unfortunately, underreporting of occupational disease and injury is a known challenge for the stakeholders in estimating the true burden, worldwide. Taking China as the country with the largest working population of 776 million in 2018, more than 200 million of its workers are exposed to multiple risks including dust, chemicals, and poison, and this number is still underreported [14].
Te DOSH published a yearly report on occupational poisoning and disease in Malaysia which shows increasing trends from 454 cases in 2005 to 9860 cases in 2019 [15]. Te documentation of occupational disease is important for workers' compensation due to occupational disease or injury. Besides that, the information is useful for the stakeholders in planning for a preventive program at the national level in line with the healthy workplace campaign [5]. In Malaysia, the highest number of reported cases was recorded in the manufacturing sector and the highest number of diseases was the occupational noise-related hearing disorders [15].
Various studies were conducted concerning the occupational health issues in Malaysia in terms of occupational diseases and specifc jobs [16][17][18][19][20][21][22], but the summarized literature was not found. Scarce evidence in the literature can summarize the recent occupational disease and injuries in Malaysia, and thus the study aims to review and summarize the occupational diseases and injuries being discussed in Malaysia from 2016 to 2021. Terefore, the underpinning of this paper is to review the occupational disease and workrelated issues that have been discussed from the year 2016 to 2021.

Materials and Methods
A thematic review uses the basic concept of any systematic literature search by constructing a set of keywords for the initial record search in the established database. Te term thematic review was introduced by Clarke and Braun as a process of identifying the important information, assigning a code to see the pattern, and summarizing the fnal themes [23]. Te review process is facilitated by computer software, namely, ATLAS.ti, which was introduced by Dr. Zairul [24].

Search Strategy.
In thematic review, the minimum number of databases required is at least two of the most common databases such as PubMed and Scopus [25]. Te fnal search was conducted on 8 September 2021. Te works of literature were searched for the period 1 January 2016 to 8 September 2021. A set of keywords was identifed, and the search strings are shown in Table 1. (i) Any review articles (ii) Focused on occupational hazard, intervention, or risk assessment without mentioning occupational disease or injury (iii) Articles are written in languages other than English (iv) Articles on review case based on DOSH report 2.3. Screening and Study Selection. Te initial metadata of the two databases were exported to Mendeley Desktop for checking a duplicate record. A total of 164 articles were selected for review. Two researchers were assigned to screen the title, abstract, and full-text article, and any disagreement was resolved by the third researcher. Figure 1 shows the details of the screening process. Te quality of study was assessed according to the National Heart Lung and Blood Institute guideline for observational cohort and cross-sectional studies [26].

Data Analysis.
All the full-text articles were read by the researchers thoroughly to familiarize themselves with the data. Te next step was to assign codes to the important text data followed by searching for themes, reviewing themes, and fnally defning and naming the themes as described by Braun and Clarke [27]. A fgure of word cloud was generated using ATLAS.ti 8. Te descriptive analysis is conducted using Microsoft Excel and Atlas.ti. 8

Results
A descriptive analysis was conducted for a total of 120 articles. Te quantitative fndings are tabulated in Tables 2-4. Te majority (65.5%) of the articles were produced by authors from medicine and health, engineering (13.3%), and biomedical (12.5%) felds as shown in Table 2. Approximately, 90.8% of the literature was based on a cross-sectional study design and 65.8% stated the sample of the respondent of more than 150 respondents. Word cloud was generated as shown in Figure 2 and shows the word musculoskeletal as the largest size equivalent to the number of literature.
Tere were seven sub-themes identifed under the theme of main health problems as shown in Table 3. Table 3 also describes other themes such as type of hazards, main job title classifcation, industry classifcation, and the specifc occupations' name according to the frequency and percentage. Table 4 shows the cross-tabulation of the main health problem theme with the explanatory themes according to the number of articles. Each of the main health problem theme is explained further in the following qualitative section of in terms of the prevalence of specifc health problem.

Qualitative Section.
Tis section describes the seven main health problems in terms of the fndings extracted from this review. All of the fndings are summarized in Table 5.

Mental Health Problems.
A total of 29 articles discussed mental health problems among workers in Malaysia. Depression, anxiety and stress, emotional exhaustion, burnout, and workplace bullying were involved mainly among HCWs (15/29), while another half of the literature was spared for other occupations such as teachers (3/29) and ofce and general workers. A study conducted among railway workers found that the mean perceived stress was 18.8 which was above the 14/15 of the normal stress level [30]. Among teachers, the prevalence of depressive, anxiety, and stress symptoms was 43.0%, 68.0%, and 32.3%, respectively [31]. Studies conducted among shift workers in the manufacturing industry reported the problem of sleepiness [32,33]. In terms of workplace bullying, 39.1% of participants reported ever being bullied in a study conducted by an insurance company among 5000 employees in Malaysia [34]. Workplace bullying was also investigated among HCW and the prevalence was 11.2% in one university hospital [35]. A study focusing on the mental health among intern doctors reported that depression, anxiety, and stress were 26.2%, 39.9%, and 29.7%, respectively, in a multihospital but a higher prevalence was noted in a study conducted in a single hospital [36,37]. A study conducted by Abd Ghafar et al. found that female gender and having depression were associated with lower quality of life among intern doctors [38]. Te prevalence of burnout among all HCWs regardless of their specifc occupation varies from 15.9% to 17.5% [39,40] before the pandemic era, while a study conducted during the pandemic era showed that more than half of surveyed respondents reported burnout [41]. Te contributing factors were higher works demands and fear of frequent exposure to COVID-19 patients [41,42].

Infectious Diseases.
Infectious diseases among workers are best described according to the workplace environment or those who had contact with the biological hazard. Most of the literature provided the laboratory confrmation test of each biological hazard in their studies. Te commonest occupational infectious disease in Malaysia is leptospirosis  [50,51]. A case of malaria was reported in Sabah from an immigrant rubber taper which caused the falciparum malaria outbreak in 2012 [52]. Besides that, migrant food handlers were reported as carriers of nontyphoidal Salmonella and practice poor hygiene practices that may cause food contamination by the pathogens [53,54]. Te recent literature discussing the COVID-19 pandemic put the HCWs at risk of COVID-19 infection. At the beginning of the pandemic, the rate of infections among HCWs was relatively low, except in a study conducted in Hospital Teluk Intan which caused the temporary closure of a few departments [55].

Work-Related Musculoskeletal Disorders (WRMSDs).
WRMSDs may cause problems among the workers who need to use physical strength during working or in the sedentary group. It can be the hand-arm vibration syndrome and pain in a specifc body part such as the neck, back, shoulder, and knee or any other body part which can be grouped as a musculoskeletal disorder. Studies conducted among hand-held grass-cutting workers and tyre shop workers highlighted the hand-arm vibration syndrome [21,56,57]. In terms of pain to the specifc body part, low back pain was among the common problems and various studies reported the prevalence among HCWs: nurses (  auxiliaries reported upper back pain which involved the neck region [62,63]. Various studies were conducted among teachers and noted the similar problems of WRMSD involving the lower back, neck, and shoulder [17,[64][65][66]. Besides HCWs and teachers, a study among commercial vehicle drivers also reported the prevalence of low back pain at 66.4% [67]. Tose who worked in a factory were exposed to MSD due to ergonomic factors such as repetitive activities [68][69][70].

Journal of Environmental and Public Health
3.1.6. Cardiovascular Disease Risks. Te trend of CVD risk prevalence is increasing in the general population and affecting the most productive population at an early age. Te sedentary administrative workers were reported to have a prevalence of smoking, physical inactivity, and unhealthy diet which were at 20%, 50%, and 87%, respectively [86]. HCWs and frefghters were reported to have obesity problems despite their knowledge and nature of work [87][88][89]. A study conducted among secondary school teachers found that normal-weight participants had metabolic syndrome which put them at risk of progressing to CVD at a later age [90].

Hearing Problems.
Hearing loss is not uncommon among factory workers and in all workplaces which are exposed to the level of noise ≥85 dB. Two studies highlighted the hearing loss issue among factory workers while one study examined the noise level in the work area [91][92][93]. Te prevalence of hearing loss was 73% among 146 respondents who worked in small and medium industries in Selangor [92]. Among the factors associated with hearing problems were occupational daily noise, length of service, infrequent use of HPD, age, male gender, and smoking status [91,92].

Discussion and Areas for Further Research
Tis thematic review summarized the recent fve years of literature discussing occupational disease and injury in Malaysia. Technically, DOSH under the Ministry of Human Resources is responsible to ensure the safety, health, and welfare of people at work. Te department also produces the yearly statistic on occupational poisoning and diseases according to ten sectors under the 1994 Act. DOSH classifed the ten sectors of work activities such as (1) manufacturing, (2) mining and quarrying, (3) construction, (4) hotels and restaurant, (5) agriculture, forestry and fshing, (6) transport, storage, and communication, (7) public services and statutory authorities, (8) utilities-gas, electricity, water, and sanitary services, (9) fnance, insurance, real estate, and business services, and fnally (10) wholesale and retail trades [15]. Te Ministry of Human Resources adapts the International Standard Classifcation of Occupations (ISCO) to come out with Malaysian version of occupational classifcation, namely, MASCO, which can be accessed in public domain [29]. Tis study used the main job title classifcation to describe the specifc occupation name. Besides Ministry of Human Resources, the Department of Statistics Malaysia (DOSM) conducts the Labour Force Survey to highlight the employment and unemployment rates. Te labour force survey used the updated version of MSIC in 2008 consisting of the updated version of industry classifcation with the current 20 groups of industries from the only nine groups for the year before 2000. Te report also stated that the highest number of workers were in Group C (manufacturing) followed by Group G (wholesale and retail trade; repair of motor vehicles and motorcycles), Group I (accommodation and food service activities), Group A (agriculture, forestry, and fshing), and Group F (construction) [94]. DOSM as the main function of recording the general population statistic difers in the industry classifcation from DOSH because DOSM needs to update the classifcation according to the recent industrial development. A standard classifcation should be used by the authority bodies in order to minimize the overlapping job scope and underreporting issues among working people [13].
Tis thematic review found that a higher number of literature focused on Group Q (human health and social work activities) followed by Group A, Group C, Group O (public administration and defense; compulsory social se-   Journal of Environmental and Public Health 11

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Journal of Environmental and Public Health Journal of Environmental and Public Health 13    16 Journal of Environmental and Public Health   In addition, they were troubled mainly with distress at the low back (34.1%) and the ankle or feet (34.1%) which had prevented the respondents from doing their regular job over the past 12 months.

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Journal of Environmental and Public Health

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Journal of Environmental and Public Health As < Al < Cu < Mn < Cr < Ni < Co < Fe (in the toenail) and Co < Al < Cu < Ni < As < Cr < Fe < Mn (in the cassette), respectively

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Journal of Environmental and Public Health Journal of Environmental and Public Health 25

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Journal of Environmental and Public Health and fshing, C: manufacturing, E: water supply; sewerage, waste management, and remediation activities, F: construction, G: wholesale and retail trade; repair of motor vehicles and motorcycle, H: transportation and storage, I: accommodation and food service activities, O: public administration and defense; compulsory social security, P: education, Q: human health and social work activities, and R: arts, entertainment, and recreation. curity), and Group P (education) [15]. Te possible reason for these fndings is due to the recent pandemic (COVID- 19) which afected the HCW group in terms of psychosocial, ergonomic, and biological hazards. Tose who work in manufacturing industries might be exposed to the physical hazard while those in agriculture may have zoonosis infection [93,95]. Te increasing number of non-communicable diseases such as diabetes, hypertension, metabolic syndrome, and obesity might afect those who were in sedentary work style [86]. Traditionally, any occupational diseases were reported to DOSH as the main authority for further investigation. Te highest reported health problem to the DOSH was occupational noise-related hearing loss, but this theme was less discussed recently. Te literature discussed more biological hazards referring to COVID-19 which afected the healthcare workers. Te occupational disease highlighted in the literature may not be reported to the DOSH because it is mainly for educational purposes. Te DOSH reported of fve, zero, four, and one confrmed cases of workers who had a psychosocial problem in 2017, 2018, 2019, and 2020, respectively, which contradicted the abundant literature on mental health as found in this study. One of the challenges reported by the previous study is the underreporting problem of the occupational disease cases which afects the worldwide surveillance system [13]. Te current trend showed that occupational diseases reported to DOSH traditionally are focusing on workers in manufacturing and construction industries while those in other industries such as education and public administration may be left behind. With the current situation of the post-pandemic era, a higher number of mental health problems arise but may not be reported to the authority. Tus, collaborative work among the authorities is needed to increase reporting of any cases suspected of psychosocial problems.
Te recent work of WHO and ILO found that the risk of long working hours defned as ≥55 hours/week is paired with the health outcomes of ischemic disease and stroke [96]. Te situation during the pandemic which exposed a group of frontliners including the HCWs and public administration and defense staf to the long working hours may contribute to a sudden cardiovascular attack. However, this may need more work since CVD is multi-factorial which includes individual lifestyle, family history, sedentary working type, and mental health problems. Even before the pandemic era, a younger age patient was seen for having a sudden attack of myocardial infarction which led to a new recommendation of CVS screening as early as 30 years [97].
According to the Occupational Safety and Health Master Plan 2021-2025 (OSHMP25), one of the indicators aims to increase the occupational diseases/injuries reported by 30% in 2025 [15]. Tis may need collaborative work among employers in both public and private industries to be responsible for data reporting. Besides that, the small and medium industries lack in providing the proper channel of healthcare service where the workers' health assessments are not conducted by the occupational health doctors but are treated as normal patients in the local health facility [98]. Te challenges are faced by primary care doctors who may be less trained in occupational health [98].

Strengths and Limitations of the Study.
Tis study used a thematic review concept to give an overview of the recent issues related to occupational disease and injury in Malaysia. Te number of reviewed articles was more than hundreds of articles, and it was managed using the Mendeley reference manager and ATLAS.ti 8 for the qualitative data analysis. Te majority of the selected studies are cross-sectional study designs, and nearly three-quarters had adequate sample sizes. Even though the cross-sectional study design lacks a causal relationship, the important content such as the type of main health problems and their prevalence can be extracted from the selected studies. Tis generated study's fndings via thematic and content analysis managed to answer the research question.

Conclusion
Tis study summarized the literature on the evidence of occupational diseases in Malaysia over the recent fve years. Te substantial number of literature on mental health problems may not be in line with the reported cases in DOSH. A psychosocial factor may be the main hazard for workers in Malaysia, worsening with the pandemic (COVID-19). Tis study highlighted that there are discrepancies between issues being discussed in literature among workers with occupational diseases or injuries being reported to the relevant authority. Terefore, working people in Malaysia should be advised to seek help if they are facing any occupational hazards at the workplace. Collaborative work between agencies must be strengthened towards providing a better healthcare service for working people.

Data Availability
Te data that support the fndings of this study are included within the article.

Ethical Approval
Tis study was registered under the National Medical Research Registration with NMRR ID-22-00058-A8U.

Conflicts of Interest
Te authors declare that they have no conficts of interest.