Relationship Between Xylene, Rq Xylene Concentration and Enzyme Activity as Indicators of Liver Function Among Shoe Industry Workers In Surabaya

Introduction

As a country develops over time, the development is also directly proportional to the high potential danger to workers; one of which is exposure to chemicals as industrial raw materials (Chen & Reniers, 2020). These chemicals, if entered into the body of workers can cause illness and health problems (Mandiracioglu et al., 2011). Some chemicals that are found in many industries are benzene, toluene, and xylene.

Xylene is a solvent with the physical properties of colorless, flammable, volatile, and has a sweet aroma (Bordoloi, 2018). This is a natural substance that is found in the contents of kerosene, coal, and others. Today many industries use xylene as a paint thinner and ink solvent (Jafari et al., 2009). In addition, this is also commonly found in the agricultural industry as a solvent and emulsifier (Efeovbokhan et al., 2021).

Xylene exposure to workers can be bad for health. According to Kurnianto (2016), several xylene exposure pathways include breathing, digestion, eye contact, and skin. Xylene that is inhaled by workers will enter and be retained in the lungs and eventually circulated to the body through the bloodstream. Many industries use xylene as a substitute for benzene (Kandyala et al., 2010). However, based on experiments conducted, xylene is more dangerous than toluene (Masekameni et al., 2019). A study (Kurnianto, 2016) was conducted whose results showed that the effect of the xylene threshold appeared at the lowest dose of toluene.

Xylene concentrations below 200 ppm can irritate the eyes and mucous membranes. At higher concentrations of xylene, exposure can cause narcotic effects (Niaz et al., 2015). Exposure to xylene ingested by workers can cause interference with the stomach and toxic effects on the liver. Meanwhile, acute exposure to xylene vapors can cause lung dysfunction and cause swelling and bleeding (Kandyala et al., 2010).

One of the health problems caused by xylene exposure to workers is the disruption to the digestive system. Indigestion can attack liver function which can be seen through SGOT and SPGT levels (Niaz et al., 2015). SGOT or Serum Glutamic Oxaloacetic Transaminase or also known as AST (aspartate aminotransferase) is one of the liver enzymes. This enzyme is located in the structure of the liver, so its appearance in the blood indicates damage or disruption in liver function (Singh et al., 2011). SGPT or Serum Glutamic Pyruvate Transaminase called ALT (alanine aminotransferase) is also a liver enzyme in the liver. Elevated levels of SGPT in the blood indicate symptoms of damage or impairment in liver function (Gowda et al., 2009).

Continuous and frequent xylene exposure by workers can cause some health problems in the long run. These health problems include visual disturbances, dryness of the nose, dermatitis, and damage to the liver and kidneys (Rajan et al., 2019). This study aims to investigate the relationship between xylene, RQ xylene concentration, and liver function in industrial workers in Surabaya. This study also leaves areas for further research on the long-term impact of xylene exposure on the liver function of industrial workers. The results of this study have direct applications in efforts to improve occupational health and safety in the industrial sector, by enabling the development of more effective policies to reduce the risk of xylene exposure. However, more research is needed to fill this knowledge gap and find more comprehensive solutions to the health problems arising from xylene exposure in the workplace.

The paper will begin with an introduction to xylene, its sources of exposure, and its potential health effects on humans. The second section will present the methodology of the study, including the study design, participants, and data collection methods. The third section will present the results of the study, including the relationship between xylene exposure and heart function in industrial workers in Surabaya. Finally, the paper will conclude with a discussion of the implications of the study for occupational health and safety, as well as recommendations for future research in this area.

Methods

This study, conducted in 2019, examines the relationship between xylene exposure and liver function in shoe industry workers. We employed a cross-sectional design, collecting data from workers in five prominent shoe industry clusters: Ketintang, Kalijudan, Jemursari, AUP, and Romokalisari. These locations were chosen due to their high concentration of workers potentially exposed to xylene. The study aimed to capture a diverse range of exposure levels by surveying workers across these clusters. Informed consent was obtained from all participants involved in the study through a well-defined process that ensured their understanding and willingness to participate. The process included information provision, opportunity for questions, voluntary participation, consent forms, confidentiality assurance, and contact information. By following these steps, the study ensured that participants were fully informed about the study and their rights.

The study included workers from shoe industry sites in Ketintang, Kalijudan, Jemursari, AUP, and Romokalisari who had worked there since 2019 or earlier, were between 16 and 65 years old, gave informed consent, had no history of medically diagnosed liver disease, and provided complete and accurate questionnaire answers. Workers from unspecified locations, those who started working after 2019, individuals under 16 or over 65 years old, those with a history of medically diagnosed liver disease, those who did not provide informed consent, those who were unavailable during data collection, and those who provided incomplete or inaccurate questionnaire answers, will be excluded from the study.

A total of 90 workers were used as the study population. Of these, 77 people were selected as samples using the accidental sampling method. This method is a non-probability sampling method where researchers select samples based on ease of access, not through a random selection process. As a result, the sample obtained is potentially not representative of the entire population (University of Greenwich, 2019). The accidental sampling method is also known as grab sampling, convenience sampling, or opportunity sampling (Alleydog, 2023).

To ensure the validity and reliability of the study results, air and blood sampling procedures were implemented. Air samples were collected using a calibrated air sampling pump, equipped with an activated charcoal absorbent tube to quantify xylene concentrations in the workplace environment. The flow rate during sampling was set at [50-200 mL/min], in accordance with NIOSH standards number 1501 for volatile organic compounds. Calibration was performed using a Chromatography Gas to ensure accuracy. Blood samples were collected using SST (Serum Separator Tubes) to facilitate serum separation for Serum Glutamic Oxaloacetic Transaminase (SGOT) and Serum Glutamic Pyruvate Transaminase (SGPT) analysis. The skin was cleaned with alcohol wipes before venipuncture, and all materials were disposed of following standard biomedical waste protocols. Blood samples were stored at 4°C and tested in the laboratory within 2 hours after collection. Enzyme levels were analyzed using spectrophotometry. The independent variables were xylene concentration and xylene RQ, and the dependent variable was liver function as indicated by SGPT and SGOT levels. Blood samples were then tested in the laboratory.

Results

Some characteristics of respondents include age, sex, level of education, and work area. The following table distributes the characteristics of respondents who work in the Surabaya shoe industry.

Based on Table 1, 25 (32.47%) of shoe industry workers aged 36-45 years with the majority of workers being male (61 or 79.22%) with the majority of final education level is senior high school (43 or 55.84%). Based on the working area of the shoe industry, 24 (31.17%) workers work in the shoe industry located in Romokalisari, Tambak Oso Wilangun, Surabaya.

Table 2 shows that of the five shoe industries in Surabaya, the majority (98.7%) of workers had a concentration of xylene exposure below the threshold value of 100 ppm. There is only one worker whose concentration of xylene exposure (103.59) exceeds the threshold, namely in Jemursari. Based on the risk level (RQ), 72 (93.5%) workers fall into the safe RQ category by RQ <1. There are still 5 (6.5%) workers that fell into the risk category.

Table 3 explains the distribution of SGOT rates and SGPT rates among workers. The normal rate of SGOT is 5-40 IU / L and SGPT is 5-35 IU/L. Based on these results it is known that 66 (85.7%) workers have normal SGOT levels. There were 58 (75.3%) workers with normal SGPT rate.

Based on Table 4 there is no relationship between xylene concentration and xylene risk level (p > 0.05). Table 4 shows that there were 71 (92.2%) workers who had an RQ level <1 with a concentration of exposure <100 ppm and there were 5 (6.5%) workers who had an RQ level > 1. While for concentrations> 100 ppm there is 1 (1.3%) worker with risk level of RQ <1.

According to Table 5, there was a relationship between SGOT and SGPT rates (p < 0.05). Table 5 also shows that there are 55 (71.43%) workers with normal SGOT and SGPT levels. There were 11 (14.29%) employees with normal SGOT rates but SGPT rates were not normal. There were 3 (3.89%) employees with a normal SGPT rate and 8 (10.39%) employees with a normal SGPT rate.

Figure 1 shows the highest average xylene concentration (122.81 ppm) is in Jemursari; the industry with the lowest average xylen concentration was Romokalisari (4.03 ppm). The highest average SGOT level was found in AUP (61.65 IU/L) and the lowest was found in Romokalisari (20 IU/L). The highest average SGPT level was found in the AUP industry (45.25 IU/L) and the lowest average was in Kalijudan (19.5 IU/L).

Figure 1. Graph Xylene Concentration with SGOT and SGPT levels.

Based on Figure 2, the highest average RQ was found in Romokalisari (0.54) while the lowest average was found in Jemursari (0.004). SGOT and SGPT levels are the same as those listed in Figure 1.

Figure 2. Graph RQ Xylene Concentration with SGOT and SGPT levels.

Table 6 shows the results of the cross tabulation test between xylene concentrations and SGOT levels in workers. Based on the chi square test there was no relationship between xylene concentration and SGOT levels in workers (p > 0.05). There were 66 (85.7%) workers with xylene concentration <100 ppm and normal SGOT levels; 10 (13.0%) other workers had abnormal SGOT levels. There are 1 (1.3%) workers with abnormal SGOT levels and exposed to concentrations >100 ppm. Based on the prevalence rate calculation, xylene concentration is a protective factor against damage to SGOT levels.

Based on Table 7 there is no relationship between xylene concentration and SGPT levels (p > 0.05). There were 58 (75.3%) workers who were exposed to xylene concentrations <100 ppm and had normal SGPT levels and 18 (23.4%) workers who had abnormal SGPT levels. In workers exposed to xylene concentrations exceeding NAV, there is 1 worker (1.3%) who has an abnormal SGPT level. Based on the calculation of the prevalence rate workers exposed to xylene concentration are included in the protection factor will cause damage to SGPT level.

Table 8 shows no relationship between RQ xylene and SGOT levels (p > 0.05). There were 61 (79.2%) workers who had RQ level < 1 and normal SGOT level and 11 (14.3%) workers who had abnormal SGOT levels. In RQ > 1 there were 5 (6.5%) workers who had normal SGOT levels. Based on the calculation of the prevalence rate of workers with RQ < 1, 7.09x greater risk of damage to SGOT levels.

Based on Table 9 there was no relationship between RQ xylene and SGPT levels (p > 0.05). There were 54 (70.1%) workers who had RQ < 1 and normal SGPT levels and there were 18 (23.4%) workers who had abnormal SGPT levels. For workers with RQ > 1 there were 4 (5.2%) workers with normal SGPT levels and 1 (1.3%) workers with abnormal SGPT levels. Based on the calculation of the prevalence rate, workers with RQ < 1 were at a risk of 1.067x greater to experience damage to SGPT levels.

Discussion

As this observational analytic study aimed to examine the relationship between xylene concentration, xylene RQ, and liver function in industrial workers, particularly in Surabaya’s shoe industry, the following findings were identified: Based on the collected data (Tables 1, 2, and 3), the majority of respondents fell within the 36-45 age range (32.47%), were male (61%), had a high school or vocational high school education (55.84%), and worked in the Romokalisari industry (31.17%). Moving on to the core objective, the correlation coefficient (R) between xylene concentration and SGOT level was found to be 0.65, indicating a moderate positive correlation. This suggests that higher xylene exposure levels are associated with higher SGOT levels in the workers. Conversely, the R-value between xylene concentration and SGPT level was -0.12, signifying no significant correlation. In simpler terms, there seems to be no clear association between xylene exposure and SGPT levels in these industrial workers.

Conclusion

This study found no association between xylene concentrations and SGOT/SGPT levels in shoe industry workers in Surabaya who were exposed below the Threshold Value (NAB) (p > 0.05. This finding suggests that xylene exposure at reasonable levels may not directly affect liver function. Other factors such as duration and frequency of exposure, dietary intake, and individual health conditions may play a greater role in affecting SGOT/SGPT levels. These findings may help focus occupational health prevention efforts on other risk factors besides xylene exposure at reasonable levels. Further research is needed to identify other factors that may affect liver function in workers exposed to xylene. Education and training programmes on occupational health related to xylene exposure need to be continued to increase workers’ awareness of potential risks and ways to prevent them.

The results of this study may be generalisable to other populations of industrial workers who are exposed to xylene at reasonable levels. However, keep in mind that this study was conducted in Surabaya and with a limited sample, so further research needs to be conducted elsewhere with a larger sample to confirm these findings. This study contributes to the knowledge of the relationship between xylene exposure and liver function in shoe industry workers in Indonesia. The findings help complement previous studies that focus on the neurotoxic effects of xylene.

This study has several limitations, including: Cross-sectional research design that cannot show cause-and-effect relationship, limited sample from one location in Surabaya, did not consider other factors that may affect SGOT/SGPT levels. Longitudinal studies are needed to examine the relationship between xylene exposure and long-term liver function. Studies with larger and more diverse samples from different locations and industries should be conducted. Studies that consider other factors such as duration and frequency of exposure, dietary intake, and individual health conditions should be conducted. Studies using other biomarkers of liver function other than SGOT/SGPT should be conducted.