| Abstract|| |
Background: In agriculture, calcium carbide (CaC2) is used as a chemical in fruit ripening and as a source of acetylene gas, which acts as a reducing agent with same fruit-ripening attributes as ethylene. The reaction between CaC2 and moisture produces acetylene, which consequently leads to ripening of fruits. Many existing studies focus on the effects of calcium carbide on fruit texture, taste, and nutritional content, but only a limited number explore the level of occupational exposure of CaC2 and its health effects among workers involved in the ripening process. Objective: The aim of this article is to assess the respiratory symptoms of agricultural workers through questionnaire and to determine the most significant sociodemographic factors contributing to respiratory symptoms. Methods: The respondents were interviewed using two set of questionnaires: a general structured questionnaire and IUALTD Bronchial Symptoms questionnaire. Data in this study were analyzed statistically using SPSS. Chi-square test was used to analyze the relationship between sociodemographic factors with respiratory symptoms. Significant level used for this study was P less than 0.05. Result: The most regular symptom exhibited by the respondents was morning phlegm (37.5%), followed by morning cough (33%), shortness of breath (25%), and chest tightness (16.7%). Age, duration of employment, smoking status, handling of calcium carbide, and awareness of the dangers of calcium carbide did not have a significant association with all the respiratory symptoms. Conclusion: Considering the prevalence of respiratory symptoms among the respondents, we suggest that further studies on the effects of CaC2 are warranted. Findings will be beneficial to creating public awareness on the effects of hazardous chemicals on human health and to increase awareness of impact of the use of calcium carbide on the health of workers working with CaC2.
Keywords: Calcium carbide, sociodemographic factors, respiratory symptoms
|How to cite this article:|
Ismail NS, Rasdi I, Mangala P S, Adidin EZ. Respiratory symptoms and sociodemographic factors among agricultural workers exposed to calcium carbide as fruits ripening agent in Kuala Kangsar, Perak: A preliminary study. Ann Trop Med Public Health 2017;10:432-5
|How to cite this URL:|
Ismail NS, Rasdi I, Mangala P S, Adidin EZ. Respiratory symptoms and sociodemographic factors among agricultural workers exposed to calcium carbide as fruits ripening agent in Kuala Kangsar, Perak: A preliminary study. Ann Trop Med Public Health [serial online] 2017 [cited 2019 Nov 16];10:432-5. Available from: http://www.atmph.org/text.asp?2017/10/2/432/208693
| Introduction|| |
Calcium carbide (CaC2) has been widely used in Asia since antiquity for ripening purposes. Malaysia is one of the countries that still use CaC2 for fruit ripening, especially mango, as a preferred choice. Ripening agent is a material used to accelerate the ripening activity and available in many forms including CaC2. Calcium carbide can stimulate ripening within 24 h and is a sought after material by farmers because it is available at a low price. Calcium carbide for fruit ripening is available in the form of small blocks or powder. In Malaysia, small blocks of CaC2 are often used. The type of CaC2 used in the ripening activity contains arsenic and phosphorus, which are hazardous to human health if consumed.
Health effects caused by CaC2 include skin irritation, which can cause rash and redness, and lung irritation, which can initiate cough and/or shortness of breath. Pulmonary edema with acute shortness of breath may occur with higher exposure to CaC2 through inhalation, and repeated exposure can cause bronchitis with coughing, phlegm, and/or shortness of breath. Calcium carbide will react with moisture when used in fruits, thus freeing acetylene, which has the ripening attribute analogous to ethylene, a natural/biologic ripening agent. Acetylene is colorless, odorless, and extremely flammable gas. In common industrial use, acetylene is not deemed to be an intense lethal hazard, but exposure to it in an occupational situation does have harmful health effects, which are linked to the existence of toxic impurities. Common impurities include ammonia, arsine, and phosphine.
Artificial fruit ripening has become dubious in recent years with emergence of various health-related issues. Acetylene gas released from the reaction of CaC2 contains phosphine in a concentration of 95 ppm, and this concentration exceeds the life and health value (IDLH) of 50 ppm set by the US NIOSH. IDLH is a condition indicating a threat to life either immediately or later or permanent undesirable health outcomes that would restrict the effected person's capability to move around unassisted. Generally, acetylene gas is not considered a major contributor to serious toxic hazards to humans, but the impurities contained therein, one of which is phosphine, cause health problems, especially to the pulmonary system and cardiovascular system. Studies by Singh in 1990 showed that out of 121 cases of phosphine poisoning due to the use of aluminum phosphide as grain fumigant, 78 (64.4%) cases showed signs of dyspnea. Similar studies on phosphine poisoning caused by the use of aluminum phosphide as grain fumigant were also carried out by Singh in 1989. These studies indicated that 25 (78%) out of 32 cases exhibited symptoms of dyspnea. There was evidence that pulmonary edema, necrosis of individual hepatic cells, and anoxic change in Purkinjie cells of the cerebellum were among the causes of death from acute exposure to phosphine.
In the studies on the effects of this substance in animals, Patoare in 2007 did histopathological analysis of rat's lung tissue to show augmentation in weight when the animals were administered different concentrations of CaC2 orally every day for 1 month. Several studies on the effects of exposure of phosphine in animals have also been carried out to estimate safe levels of occupational exposure. Studies by Klimmer on rats, cats, and guinea pigs showed that animals exposed to phosphine at 5 ppm for 31.5 h, 5 ppm for 41.5 h, and 5 ppm for 26.6 h, respectively, died due to inner organ congestion and pulmonary edema. Thus, the objectives of this preliminary study were to assess the respiratory symptoms of agricultural workers through questionnaires and to determine the most significant sociodemographic factors contributing to respiratory symptoms.
| Materials and Methods|| |
The study population consisted of managerial and fruit farm's staff from MARDI Station Kuala Kangsar, Perak. There were 24 respondents at the time this study was carried out. The criteria for the preliminary study were male or female sex and age between 18 and 75 years. The respondents were interviewed using two sets of questionnaires; one of which was a general structured questionnaire to gain information on sociodemographic factors and personal characteristics and the other was IUALTD Bronchial Symptoms questionnaire to find the most valid combination of symptoms-based items for identification of lung function. All respondents were assisted in answering the questions in the questionnaires.
The general structured questionnaire was used to cover the sociodemographic factors in this study, including age, duration of employment, smoking status, handling of calcium carbide, and awareness of the dangers of calcium carbide, while the IUALTD questionnaire encompassed the respiratory symptoms experienced by the respondents during the last 12 months. The respiratory symptoms covered in this study were shortness of breath, chess tightness, morning phlegm, and morning coughs. Data in this study were analyzed statistically using SPSS. Chi-square test was used to analyze the relationship between each respiratory symptom with age, duration of employment, smoking status, handling of calcium carbide, and awareness of the dangers of calcium carbide. Significant level used for this study was P less than 0.05.
| Results|| |
Four categories of age used in this study were 18-30, 31-40, 41-50, and 51-60 years. The mean age was 42 ± 9.98 years, and 58% of them were more than 40 years old. The mean for duration of employment was 13.6 ± 11.34, and 37.5% of the workers had been working at the facilities for almost more than 10 years. As for workers' smoking status, only 8% of them were classified in a casual smoker group, 33% as heavy smokers, and the remainders as nonsmokers. Of 24 subjects evaluated, only 25% had experience of handling calcium carbide at their workplace and only 16% of them were aware about the dangers of calcium carbide on human health.
Four symptoms were used for this study including shortness of breath, chest tightness, morning cough, and morning phlegm. These symptoms were experienced by the respondents during the last 12 months. Of all the symptoms, the most regular symptom exhibited by the respondents was morning phlegm (37.5%), followed by morning cough (33%), shortness of breath (25%), and chest tightness (16.7%) as shown in [Figure 1].
Relationship between sociodemographic factors and respiratory symptoms
This study shows that respondents with the highest prevalence of shortness of breath for the past 12 months (12.5%) were among those aged 41--50 years old. However, as for the duration of employment, those working for 5 years or less exhibited the highest symptoms of morning phlegm (16.6%) and chest tightness (8.3%). As for smoking status, the nonsmoker group consisted of the maximum number of respondents with the highest indicators of shortness of breath, morning cough, and morning phlegm of 16.7, 16.7, and 20.8%, respectively, compared with casual smokers and heavy smokers.
The findings also indicated that age, duration of employment, smoking status, handling of calcium carbide, and awareness of the dangers of calcium carbide did not have a significant association with all the respiratory symptoms. [Table 1] shows the relationship between the sociodemographic factors and respiratory symptoms.
|Table 1: Relationship between respiratory symptoms and sociodemographic factor|
Click here to view
| Discussion|| |
The finding of this study showed that all sociodemographic factors did not have a significant association with respiratory symptoms. Calcium carbide exposure may contribute to this finding. Occupational exposure to carbide can occur through inhalation during ripening process, wherein the carbide dust may accumulate on the mucous membrane. In addition, in agricultural setting, other sources such as pesticides and herbicides may contribute to the development of respiratory symptoms. In addition, the duration of exposure to calcium carbide and the quantity of the carbide used for ripening purposes may be contributing factors in the relationship between sociodemographic factors and respiratory symptoms. As for smoking status, factors such as the number of cigarettes taken in 1 day and the duration of smoking may have potential influence on the association with respiratory symptoms.
Furthermore, the methods of application also may play an important factor in determining the exposure to workers. Two methods for calcium carbide application on fruits have been used commercially. In the first approach, stockpile of fruits is placed in a room. Next, calcium carbide is strewed in some areas in the room and fruits are covered with craft paper. In other approach, calcium carbide is wrapped in a paper or cloth and then placed at the bottom of the palm leave baskets. Heaps of fruits are loaded into the baskets, which are then covered with craft paper in order to increase the temperature and maintain humidity. The baskets were then kept in a closed room for 3-4 days.
| Conclusion|| |
In summary, other factors such as education level, duration of exposure to carbide, and use of protective personal equipment (PPE) can be considered in order to analyze the association with respiratory symptoms. It is notable to scrutinize and examine the current handling of calcium carbide, since it is used quite extensively in Malaysia, mainly due to its cheaper price. Further study with bigger sample size is necessary to identify the factors affecting respiratory symptoms among fruit farmers. The finding of this preliminary study will be beneficial to public because it can be used to create public awareness on the effect of hazardous chemicals on human health and how to minimize its risk and increase worker's awareness on the health impact of the use of calcium carbide on workers and to encourage workers to use PPE when handling calcium carbide.
The author would like to show the gratitude to all those who were involved in this study. Appreciation also goes to University Putra Malaysia for providing data and technical support for this review article. We would also like to convey our gratitude to MARDI Perak for providing respondents for this study.
The ethical approval of this study was obtained from Ethic Committee, Universiti Putra Malaysia (reference number: FPSK (exp16) p100).
Financial support and sponsorship
This study is funded by IPS Putra Grant provided by UPM and the study scholarship is sponsored by MARDI.
Conflicts of interest
There are no conflicts of interest.
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Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia
Source of Support: None, Conflict of Interest: None