Air Benzene Level is associated with Urine Phenol Level and Health Complaints in Shoes Home Industry Workers in Jampirogo, Indonesia

Introduction

The informal industrial sector holds a very large share in developing countries including Indonesia. The informal sector is a sector that is not organized, irregular, and mostly legal but not registered [1]. One type of informal business that is developing in Indonesia is shoes industry. Shoes home industry became the main contributor to Indonesia’s Gross National Product as the third largest national income after the wood and textile industry in the early 1990s. Thanks to the development of the industry, about 40 percent of shoe exports were sent to the United States market and 33 percent were sent to Europe, the rest was exported to African countries, the Middle East and South America. At its peak in 1996 Indonesia was able to export 250 million pairs of shoes by almost US $2.29 billion, since then the volume of shoes industry exports declined until in 2002, shoes industry exports were only US $1.4 billion. As a result of the economic crisis due to falling exports, shoes production remains one of the main industries in Indonesia [2]. In 2013 the value of Indonesian shoes exports reached US $3.86 billion, with the value of these exports Indonesia was able to meet around 3 percent of the world’s needs for shoes products [3].

The shoes home industry plays an important role in creating employment for the community, but in order to maintain the quality and existence of the products obtained are often not matched by adequate protection against work risks that are associated with hazardous equipment and materials [4]. In general, the process of making shoes includes several stages of work starting from making designs or patterns of shoes, preparing the upper part of the shoe (making patterns, cutting patterns, lining, decorating, sewing, and insoles), preparing the bottom of the shoes (outer soles, gluing, lining), attaching the upper part of the shoe and the bottom of the shoe (gluing, sewing, nailing), finishing (cleaning, smoothing), packing for further delivery to the consumer or market in the production process using a variety of equipment [5].

Tools and materials used in making shoes are heating machines (ovens), scissors, hammers, wood footprints, adhesives such as glue, gasoline, latex, shoe soles, sponges, and roll an material. The glue used in the shoe gluing process uses two types of glue, white glue and yellow glue. Yellow glue is used to connect openings so that it is usually used on the surface and finishing, while white glue is generally used for patching the soles because of its much stronger adhesion. The high demand for shoes on the market affects the use of glue from the production process. Research conducted by the Director General of Community Health Development of Indonesia, states that the glue contains organic solvents that is 70% toluene and about 1-2% benzene [6, 7].

Out of the various tools and materials used in the shoe- making process, chemicals are a high-risk hazard. The use of chemical material which is widely used in shoes home industry of is organic solvent. This makes it very possible for workers to experience adverse effects from the use of chemicals in the work process. Chemicals in this case are glues or adhesives that are applied to the production process. The use of glue in the shoe making process is an unavoidable activity. In general, glues or adhesives contain various mixtures including benzene and toluene as organic solvents. Benzene has been known as a good organic solvent for various industrial processes of the rubber industry, shoes, and paint solvents, components in motor fuels, components in detergents, pesticides, and pharmaceutical manufacturing [8, 9, 10]. Benzene is an excellent solvent for latex rubber and has been used extensively in the rubber industry throughout the 19th century. The use of glue containing benzene can pose serious health risks because of the carcinogenic content for humans. According to the American Conference of Government Industrial Hygienists (ACIGH) in 2006 stated that the threshold value of benzene in the workplace was 0.5 ppm and included in the category A-1 which means it was proven to have carcinogenic properties in humans [11]. The National Institute for Occupational Health and Safety (NIOSH) in 2005 established the Recommended Exposure Limit (REL) of 0.1 ppm for 8 working hours [12]. According to Minister of Manpower and Transmigration Regulation No. 13 of 2011 states that the benzene threshold value is 0.5 ppm [13]. Benzene has volatile properties so it is easily exposed by humans. Benzene enters the human body through 3 pathways, namely absorption through the skin, inhalation and ingestion. Through inhalation, benign absorption is around 70-80% in the first 5 minutes, and 20% to 60% for the next hour. Inhalation is the most likely route of chemical exposure, especially at work [14, 15]. Inhaled benzene will enter the human body and will undergo major metabolism into benzene epoxide. In the liver, benzene epoxide is an unstable compound and will soon undergo changes to form phenols. Within 2 days after exposure to benzene most of the metabolites from benzene will be removed together with urine. Therefore, phenol levels are used as biological indicators of benzene exposure in the workplace, high levels of urine phenols indicate higher degrees of benzene poisoning [16, 17].

The nature of benzene which is volatile to free air so that if a source of exposure is left continuously exposed in a workplace, the greater the concentration of benzene in the work environment [18]. The signs and symptoms of chronic poisoning that will arise due to exposure to benzene include headaches, dizziness, nausea to vomiting, difficulty concentrating, and anemia which is often accompanied by bleeding under the skin and mucosa. The clinical effects of benzene systemically cause disorders in the cardiovascular, respiratory, neurological, gastrointestinal, liver, kidney, endocrine and reproductive systems, dermatology, local effects, hematological, immunological, and allergic [14, 19, 20, 21, 22]. The American Petroleum Institute (API) states that benzene can certainly cause leukemia and not tolerated even the slightest (zero ppm level). Whereas in epidemiological studies mention the relationship between benzene exposure and leukemia conducted on 28,500 shoe or sandal industry workers showed an annual incidence of leukemia as much as 13 out of 10,000 which is greater than the incidence of the general population which is only 6 out of 100,000 [14]. Several cases of benzene usage in the shoe industry were found in 1946-1956 in the United States there were 107 cases due to concentrations of benzene exposure that exceeded 400 ppm. From the incident found hemophaty and thrombocytopenia. In 1945-1955 there were 125 cases of decreased platelets and abnormal liver function due to benzene exposure in excess of 400 ppm in the shoe industry [22].

The Jampirogo Mojokerto home industry is one of the home industries owned by the Jampirogo Mojokerto community, where the majority of the population works as shoe craftsmen. The Jampirogo Mojokerto shoe home industry which was the site of this research was established in 2016. The building design is done separately in one building using walls as a partition between the gluing room, packing room and household space. The area of the gluing room is approximately 105 m2, the building area of the packing room is 70 m2 and the building height is approximately 2.5 m. The number of shoes produced by the Jampirogo Mojokerto shoes home industry is approximately 40 scores per day and can increase on certain days, so that the more demand for shoes, the more glue is used in the shoe making process. The amount of glue used during the shoe making process is approximately 24 kg per month. The use of glue in the shoe production process certainly makes it easier for workers to experience exposure to benzene in the workplace that cannot be avoided. The use of glue which is known to contain hazardous substances to humans should receive attention from the government such as monitoring of its use, but most health and safety monitoring and the work environment are only carried out on the types of large scale industries while small to medium industries still receive less attention to health and safety and the work environment of hazardous materials used during production such as benzene in the work environment. This research was conducted to study and find out the effects of benzene exposure with urine phenol levels and health complaints on workers exposed to benzene in the Jampirogo Mojokerto shoes industry. The purpose of this study was to analyze the association between air benzene level with urine phenol level and health complaints in workers exposed to air benzene in the Jampirogo Mojokerto shoes home industry.

Methods

This study used a cross sectional study design, because the measurement of the variables to be done at the same time. The location of the study was conducted in one of the Jampirogo Mojokerto shoes home industries conducted in June to July 2019. Data used in this study were obtained through measurement of benzene in the air, measurement of urine phenol levels and interviews using a questionnaire to determine the work behavior and health complaints felt by participants. The study population was consisted of the environmental population and the worker’s population. Environmental population was population of benzene levels in the air of the Jampirogo Mojokerto shoes home industry. The worker population was all workers who were working in the Jampirogo Mojokerto shoes home industry, namely the gluing area and the packing area. The inclusion criteria set in this study was male, working at least 3 years, working hours at least 8 hours per day, workers who were permanent workers and were willing to become study participant. Environmental samples were levels of benzene in the air taken at two measurement points, namely shoe shading room and shoe packing room, at 3 different times, morning, afternoon and evening.

Sampling of participant could be obtained using the formula of the sample size of two populations [23]. Then the sample size in this study was 13 workers exposed to air benzene. Furthermore, from the sample, 13 workers who were not exposed to benzene were added as a control group, then the sample size in this study was 26 workers. Workers who were selected to be subsequently will also be taken urine samples then measured and examined in the laboratory of Integrated Polytechnic Laboratory of the Health Ministry, Surabaya. The variables in this study consisted of independent variables namely levels of benzene in the air, age, working hours, working days, length of employment and nutrition status. The dependent variable was phenol urine. After the data were collected, it was analyzed further.

Discussion

This study result was in line with previous study which showed the results of the measurement of benzene in the shoe industry area exceeding the TLV of 2.97 ppm [25]. This study was also in accordance with previous study that the benzene levels in the air had a concentration of 0.002-34 ppm. People who live in cities or industrial environments in general would be exposed to higher benzene levels [15]. High benzene levels were affected by several environmental factors including ambient temperature and humidity in the workplace when measured. The results of the ambient temperature increased during the afternoon was 33°C, this showed the temperature in the gluing room has increased which causes high benzene levels in the workplace air, while the humidity in the packing room remained stable at three measurement times namely morning, afternoon and evening were different with the gluing room decreased in humidity during the afternoon was 52%. The high benzene levels in the gluing room were affected by the high ambient temperature at the time of measurement and lack of humidity which caused the benzene levels in the air exceed the TLV. In addition, high benzene levels in the air were affected by inadequate ventilation, this made the benzene vapor from the glue used could not circulate with outdoor air. This was certainly a risk for gluing workers, owners of the shoes home industry and surrounding community. This was caused by the location of the gluing room with households that were only next to each other and the wall as a divider between the two, but there was a door as a connecting path between those rooms so that benzene could spread to the surrounding environment. The close distance between the shoes home industry building and the resident houses in Jampirgo Village Mojokerto allowed the surrounding community to be exposed to benzene. Direct exposure that could cause workers health effects needed to be engineered to reduce health risks due to the use of chemicals in the work process.

Benzene entered the human body in the form of vapor through the main inhalation and absorption pathways through the lungs with an amount of 40-50% of the total benzene that can enter the body. Benzene would be easily absorbed through inhalation; pulmonary resistance could absorb benzene reaching about 50% for several hours of exposure between 2 - 100m3. Benzene in high air would easily enter the human body through inhalation as its main pathway, which would then go through a metabolic process to become phenol urine. The metabolic process in the human body was affected by several factors, including the characteristics of respondents.

Workers who were exposed to benzene continuously would have serious health effects on humans. A study stated that someone who was exposed to benzene continuously could experience nervous disorders. Fatal respiratory exposure was reported that can cause disorders with the brain. Chronic effects caused by exposure to benzene were disorders of the nerve with symptoms such as insomnia and easy to forget [15]. In addition, it could cause hematological disorders to IARC leukemia in OSHA (2011) stated that chronic benzene exposure of 10 ppm could increase 12- 120 cases of leukemia per 1000 workers, while for 1 ppm exposure could increase 1.4-14 cases of leukemia per 1000 workers [26]. The measurement results in shoes gluing room Jampirogo Mojokerto exceeded 1 ppm but still below 10 ppm, therefore, workers in shoes gluing room Jampirogo Mojokerto had a risk of leukemia per 1000 workers. The statistical analysis revealed a very significant difference in urine phenol levels between exposed and unexposed groups. These results indicated that benzene exposure in the workplace was able to affect urine phenol levels then that urine phenol levels in the two groups of workers were different significantly. These results were supported by the results of measurements of benzene levels in the air of exposed group that exceeded the TLV. Benzene

that entered the body would metabolize into benzene epoxide in the liver, the result of metabolic processes was an unstable compound, that it would change shape to phenol which the body would excrete at the same time through urine, therefore urine phenol levels were used as a biological indicator of benzene exposure to workers.

The American Conference on Governmental Industrial Hygienists (ACGIH) had set 250 mg/g creatinine urine phenol as a Biological Exposure Indices (BEIs) for benzene exposure in the workplace [11, 28]. The main BEIs in the exposure index were not the level which health effects might occur from benzene exposure. The acute effects of benzene exposure with very high concentration through inhalation resulted in depression of the nervous system and could result in death. At the initial stage benzene mainly affected the central nervous system with the main signs feeling drowsiness, dizziness, headaches, vertigo, and loss of consciousness. The Agency for Toxic Substances and Disease Registry (ATSDR) data stated that the health effects arising from benzene exposure were found in metabolic systems in the body such as respiration, digestion, cardiovascular and then the impact on the reproductive system which would result in babies born prematurely to infertility and blood disorders that could cause leukemia [15]. In the clinical effects of systemic benzene exposure caused disorders in cardiovascular, respiratory, neurological, gastrointestinal, liver, kidney, local systems, hematological, immunological, metabolic and allergic reactions [15, 19, 20, 21].

Nervous system complaints that often occurred in respondents exposed group were shoulder pain, difficulty sleeping, difficulty concentrating and headaches. While digestive complaints that were often felt in the unexposed group were decreased appetite and abdominal pain. These results were in line with research by Tanasorn T, et al. [19] which showed that chronic benzene exposure at workplace caused nervous system and hematological disorders in refueling station Bangkok, Thailand workers with symptoms of dizziness, drowsiness and fatigue. In the Agency for Toxic Substance Registry (ATSDR) and the American Conference of Government Industrial Hygienists (ACGIH) also stated that research that had been done in humans, indicated that there was a causal relationship between acute effects through respiratory benzene exposure at high concentration and symptoms indicated disorders of nervous system and hematological. The acute effects caused by lethal and non-lethal benzene exposure caused symptoms such as drowsiness, headaches, vertigo, tremors, delirium, and loss of consciousness. These symptoms were occurred in workers who work in areas with benzene concentration problems [15, 18]. The common exposure pathway for workers and needed to be paid attention to was through inhalation, the easy way of benzene entering the body due to the benzene characteristic which volatile in the air. The presence of dangerous concentration of benzene could be identified through measurements of benzene in the air that exceeded the TLV. Acute effects that could be caused by benzene vapor such as irritation, ear buzzing, nausea, vomiting, chest pain, difficulty breathing, abnormal heart rate, headache, weakness, disorientation, impaired vision, lung damage, blood disorders, paralysis, spasms and convulsions coma. Benzene vapor can cause central nervous system, life and throat depressions. While the chronic effects due to benzene exposure vapor in the workplace could cause hearing loss, kidney damage, liver damage, nervous system damage, productive disorders and cancer [29, 30]. Several review articles mention epigenetic modifications that correlate with benzene exposure. This is mechanically linked to susceptibility to disease due to benzene exposure [31].

Conclusion

Based on the results of the research, that it was found the benzene levels in the shoes gluing room exceeded the threshold limit value (TLV), there was very significant higher in urine phenol levels in workers exposed to benzene in the workplace compared to control group. The health complaints that often felt by workers in the shoes home industry in Jampirogo, Mojokerto Regency, East Java Province, Indonesia were nervous system and hematological complaints. Therefore, it is concluded that the presence of benzene exposure in the workplace affected high phenol levels in workers and health complaints in the shoes home industry Jampirogo Mojokerto workers. It is recommended that the shoes home industry in Jampirogo Mojokerto workers shall use personal protective equipment such as respirators, add air ventilation at workplace and work rotation policies for gluing workers and packing section workers as well.

Acknowledgment

The authors are seriously indebted to the shoe home industry workers in Jampirogo, Mojokerto Regency, and Indonesia for their participation in this study and the analyst from the Integrated Polytechnic Laboratory of the Health Ministry, Surabaya for her assistance in sampling and measurement of air benzene levels.