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ORIGINAL ARTICLE
Year : 2016  |  Volume : 29  |  Issue : 3  |  Page : 757-761

Respiratory and auditory health disorders among workers in a plastic factory (industrial zone, Queisna City, Menoufia Governorate)


Department of Public Health and Community Medicine, Faculty of Medicine, Menoufia University, Egypt

Date of Web Publication23-Jan-2017

Correspondence Address:
Asmaa A Ahmed
Menoufia, 32511
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.198804

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  Abstract 

Objective
The aim of the study was to investigate auditory and respiratory health disorders among Egyptian workers in a plastic industry as well as assess the workplace environment in the same factory.
Background
The common health hazards associated with plastic manufacturing processes include noise, and exposure to respirable airborne particulates, especially polyvinyl chloride (PVC) and styrene, that lead to occupationally induced hearing loss and chronic effects such as decreased pulmonary function and lung disease.
Participants and methods
A cross-sectional comparative study was carried out in 180 workers in a plastic factory in Queisna City, Menoufia Governorate, Egypt, and in 60 nonoccupationally exposed individuals, who served as the control group. An environmental study of dust, fumes, and noise levels was carried out. Spirometric measurements were taken and air conduction audiometric examination was performed.
Results
The mean values of PVC, styrene concentrations, and noise levels are higher than the national and international permissible levels. Plastic factory workers had a highly significant prevalence of chest and auditory manifestations as well as deteriorated spirometric measurements and abnormal audiometric findings.
Conclusion
Exposure to a high level of PVC, styrene, and noise is implicated in the increase in frequency of chest manifestations, early spirometric changes, and occupationally induced hearing loss. Use of an automated plastic grinding machine to decrease the exposure to dust as well as use of good-quality personal protective equipment, especially masks and ear mufflers, is recommended.

Keywords: auditory, plastics, polyvinyl chloride, respiratory, styrene and noise


How to cite this article:
Abdel-Rasoul GM, Abu-Salem ME, El Shazly HM, Allam HK, Salem EA, Ahmed AA. Respiratory and auditory health disorders among workers in a plastic factory (industrial zone, Queisna City, Menoufia Governorate). Menoufia Med J 2016;29:757-61

How to cite this URL:
Abdel-Rasoul GM, Abu-Salem ME, El Shazly HM, Allam HK, Salem EA, Ahmed AA. Respiratory and auditory health disorders among workers in a plastic factory (industrial zone, Queisna City, Menoufia Governorate). Menoufia Med J [serial online] 2016 [cited 2020 Apr 3];29:757-61. Available from: http://www.mmj.eg.net/text.asp?2016/29/3/757/198804


  Introduction Top


The plastic industry depends on two main substances: polyvinyl chloride (PVC) and styrene. PVC is a hard, tough, lightweight, highly versatile polymer with excellent surface hardness and high scratch resistance, good electrical properties, and good ultraviolet resistance. Styrene is a clear, colorless liquid that is derived from petroleum and natural gas by-products but also occurs naturally. Styrene is used to manufacture plastic materials used in thousands of remarkably strong, flexible, lightweight products that represent a vital part of our health and well-being [1] .

The most commonly used plastic polymers are (a) thermoplastic resins such as polyethylene, PVC, polypropylene, polystyrene, styrene acrylonitrile, polycarbonate, and acrylic; and (b) thermoset resins such as polyurethane, epoxy, phenolics, and polyester [2] . PVC is one of the most commonly produced and used plastic materials [3] .

Common health disorders among workers in the plastic industry are related to massive exposure to PVC, which is toxic through all routes of exposure - inhalation, ingestion, and skin contact - and is also carcinogenic in humans. Inhalation of vinyl chloride causes coughing, wheezing and breathlessness, headache, ataxia, drowsiness, and coma. Ingestion of vinyl chloride causes nausea, vomiting, diarrhea, abdominal pain, and sometimes hematemesis [4] . At low doses, styrene may cause irritation in the respiratory tract, and at high concentrations (>100 mg/m 3 ) it may cause chronic bronchitis and obstructive pulmonary changes [5] . Occupational exposure to styrene is related to an increased risk for hearing loss. Combined exposure to noise and styrene seems to be more ototoxic than exposure to noise alone [6] . Styrene is toxic to the brain and nervous system in workers with longer-term exposure [7],[8] .

Nevertheless, there is no clear knowledge of the level of exposure at which PVC and styrene exert adverse effects. Few Egyptian studies can be found in this field, such as the work of Helal and Elshafy [9] . Therefore, this work aimed to study respiratory and auditory health disorders among Egyptian workers in a plastic factory, as well as assess the workplace environment in the same factory. Similar studies were carried out on workers in different industries in the same area (industrial zone, Queisna City, Menoufia Governorate) [10] .


  Participants and methods Top


This study took place in a plastic factory (in industrial zone, Queisna City, Menoufia Governorate, Egypt) between September 2013 and October 2014. Approval from the factory was obtained, and all participants gave written informed consent before inclusion. The consent form was developed according to the international ethical guidelines for biomedical research involving humans, as prepared by the Council for International Organizations of Medical Sciences in collaboration with the WHO [11] .

The industrial processes in this factory included the following: (a) grinding and recycling of PVC: waste plastic material is reprocessed using granulators with new stock; (b) plastic injection molding, where plastic material is fed into a hopper that feeds into an extruder, which pushes the plastic into a heating chamber for melting of the plastic and then the molten plastic is forced at high pressure into a closed cold mold; (c) film casting: molten thermoplastic is cast into slabs to form a thick sheet; (d) shaping and finishing: bonding the rigid plastic sheet for general fabrication was done as for shaping the internal coating of doors and shelves of refrigerators.

A cross-sectional comparative study was designed to study 180 occupationally exposed male workers from different departments in the studied factory after exclusion of nonresponders and application of exclusion criteria, which included workers with chest diseases, chronic diseases, or any auditory diseases before employment in this plastic factory. A control group of 60 men, from among relatives of the exposed group, who were never exposed to PVC or styrene at work were matched with the exposed group for age, residence, education, and income.

Participants were interviewed by trained investigators at the factory clinic during the morning shift. At each workplace visit, demographic data, smoking status, medical history of chest and auditory diseases, employment history (including years of working in the industry and wearing of protective clothes), and past history of diseases (like mental disorders, nervous diseases, hypertension, diabetes mellitus, liver and kidney diseases, or use of antipsychotic drugs, as well as skin, chest or eye allergies) were gathered by means of a predesigned questionnaire. The questionnaire was prepared and validated by the researchers and was pilot tested on 15 workers and five controls to test reliability. Modifications were made according to the results obtained.

In addition, spirometric measurements were taken at the factory clinic using the portable Spirolab, Rome, Italy (MIR 010) to determine forced vital capacity (FVC%), forced expiratory volume in the first second (FEV 1 %), forced expiratory ratio (FEV 1 /FVC%), forced expiratory flow (FEF 25-75 %), and peak expiratory flow (PEF%). The best value of three technically acceptable maneuvers was recorded and expressed as percentages of predicted value.

Using a diagnostic audiometer AS 67 (Danplex, Spain), air conduction audiometric examination was performed at different frequencies (250, 500, 1000, 2000, 4000, 6000, and 8000 Hz) for right and left ears separately for exposed workers and controls. Three measures were taken at 1000 Hz: at the beginning, during, and at the end of the assessment. The mean intensity of three measurements at 1000 Hz was taken to assure the compliance of the individual.

All environmental measurements were taken twice a year by Tabbin Institute for Metallurgical Studies Central Laboratory for the Studies Industrial Pollution, Cairo. Noise was measured using a sound level meter (ANSI type Model 452) at the levels of the workers' ears. Multiple readings were taken from different departments of the factory and the mean reading was calculated. Air samples from different departments of the factory were taken at the breathing zone of workers to measure mainly PVC and styrene levels. Three readings were taken from different departments of the factory and the mean value was calculated.

Data management

Student's t-test for continuous quantitative parametric variables was used. The χ2 -test was used for categorical variables. Fisher's exact test was used for categorical variables when the expected value was less than 5. Pearson's correlation coefficient was used to study the correlation between two quantitative variables. Comparisons of data were made with overall α error set at 0.05 (two-tailed). Analyses were performed with SPSS (v. 20; SPSS Inc., Chicago, Illinois, USA) and Epi Info [version 3.3, October 2004; Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA].


  Results Top


The mean values of both PVC and styrene levels were higher than permissible by the Egyptian Ministry of Trade and Industry, Law 4 Decree 1095/2011 [12] and TLV of NIOSH [13] in both grinding and injection departments. Further, the noise level was higher than permissible by the Egyptian Environmental Law 4 [14] and NIOSH, 1998 [15] in the grinding department, as shown in [Table 1].
Table 1 Mean±SD of environmental measurements in the working environment of the exposed group


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There was a nonsignificant difference between the exposed and nonexposed groups regarding sociodemographic data (age, income, education level, residence, marital status, and smoking habit), vital signs, BMI, and past clinical history (P > 0.05). Plastic factory workers had a highly significant prevalence of chest disorders, as shown in [Figure 1].
Figure 1: Respiratory manifestations among the studied groups.

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Deteriorated spirometric measurements (FEV 1 %, FEV 1 /FVC%, FEF 25-75 %, PEF) were observed in exposed workers than in controls (P < 0.05) ([Table 2]). This deterioration was significantly negatively correlated with duration of work (in years) for FEV 1 %, FEV 1 /FVC%, and PEF% (P < 0.05) ([Table 3]).
Table 2 Mean±SD of spirometric measurements in the studied groups


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Table 3 Correlation between duration of employment (in years) and spirometric measurements in the exposed group (n=180)


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About 17.8% of exposed workers had hearing impairment (ranging from mild to moderate/severe degree) and V-dip depression (65.6% of hearing impaired workers) as detected by audiometric findings ([Table 4]).
Table 4 Distribution of audiogram findings in the exposed group


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Exposed workers in the grinding department (which had the highest levels of PVC, styrene, and noise) suffered from lower spirometric measurements for FEV 1 %, FEV 1 /FVC%, FEF 25-75 %, and PEF% (P < 0.05) ([Table 5]).
Table 5 Mean±SD of spirometric measurements in workers in grinding and other departments


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Common health disorders among workers in the plastic industry are related to massive exposure to PVC, which is toxic through all routes of exposure - inhalation, ingestion, and skin contact - and is also carcinogenic in humans [4] . Occupational exposure to styrene is related to an increased risk for hearing loss. Combined exposure to noise and styrene seems to be more ototoxic than exposure to noise alone [6] .

In the studied factory, the mean values of PVC and styrene in the grinding department were higher than the permissible level laid down by The Egyptian Ministry of Trade and Industry, Law 4 Decree 1095, 2011 [11] , and TLV of NIOSH, 2002 [12] . This result is in agreement with that of Helal and Elshafy [9] .

Because of ventilation errors in the working environment of the factory, as well as the added effects of dust and fumes present in the factory and/or smoking, chest manifestations (rhinitis, cough, expectoration, and dyspnea) and deteriorated spirometric measurements (especially obstructive ventilator function) were significantly more prevalent in the exposed group, especially in the grinding department. These results were seen despite the fact that all spirometric measurements were still within normal values. This might be due to early physiological changes in ventilatory functions resulting from work in this factory.

These results are in concordance with previous studies of Helal and Elshafy [9] , Dykewicz [16] , and Checkoway and Cullen [17] , who revealed that styrene exposure leads to chronic bronchitis and obstructive pulmonary changes. However, another study conducted by Ng et al. [18] reported an association between PVC exposure and a restrictive type of lung function impairment. Moreover, a significant negative correlation was found between duration of employment (in years) and spirometric measurements among exposed workers. This correlation supports the findings of Mogel et al. [19] , who reported that prolonged duration of styrene exposure leads to chronic inflammation due to increased severity of the obstructive impairment and the liability to chronic obstructive pulmonary diseases. In contrast, an Indian study [20] reported that duration of exposure did not affect the lung functions of workers in a plastic recycling factory.

The noise levels in the grinding department were higher than the maximal permissible limit laid down by the Egyptian Environmental Law 4/1994 [13] inside closed working areas (8 h/shift) and by NIOSH, 1998 [14] . Thus, auditory disorders found among workers in this factory may be related to this exposure to a high noise level. This result is in agreement with that of Atmaca et al. [21] , who measured noise level in concrete traverse, cement, textile, and plastic factories located in Turkey and revealed the highest noise levels in these industries as 107, 106, 100, and 99 dB, respectively.

Moreover, the exposed group experienced a significantly higher prevalence of all auditory manifestations (hearing loss, tinnitus, and earache) and auditory findings (moderate to severe hearing impairment and V-dip) especially in the grinding department. Farah et al. [20] reported a high prevalence of hearing loss and sensations such as ringing, and leakage in the ears. Nelson et al. [22] found that 16% of the hearing loss in adults could be attributed to occupational noise.

Summary and recommendations

Exposure to high levels of PVC, styrene, and noise is implicated in the increase in frequency of chest manifestations, early spirometric changes, and occupationally induced hearing loss. Use of an automated crushing machine for grinding plastic to decrease exposure to dust as well as use of good-quality protective equipment such as masks and ear mufflers to decrease respiratory and auditory manifestations is essential. Spirometry and audiometry are recommended in pre-employment and periodic medical examinations.

Acknowledgements

The authors thank all workers and participants who willingly participated in the study, and the administrator of the factory who facilitated access to the study group, especially the factory manager.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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