Study on Physiological Effects on Palm Oil Mill Workers Exposed to Extreme Heat Condition

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1 Journal of Scientific & Industrial Research Vol. 74, July 2015, pp Study on Physiological Effects on Palm Oil Mill Workers Exposed to Extreme Heat Condition S NurIzzate, M T S Bahri*, K Karmegam and N Y Guan Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, University Putra Malaysia, UPM Serdang, Selangor, Malaysia Received 28 August 2012; revised 26 September 2014; accepted 3 April 2015 The objective of this study was to determine heat exposure on palm oil mill workers and its effect on physiological changes in them. Parameters considered environmental temperature, relative humidity, metabolic workload, body core temperature, blood pressure and heart rate. The average time of monitoring was 2 hrs for intermittent exposure and 8 hrs for overall exposure. Workers were exposed to moderate heat stress during this study period. There were significant differences between heat exposure and physiological changes before shift and after working for 2 hrs and 8 hrs, respectively. Metabolic workload of respondents in medium work category was kcal/hr in respect to ACGIH level. Overall heat exposure levels in all divs. in this palm oil mills were found unsuitable for working duration of 8 hrs a day. This study also found that the WBGTin value exceeded the limit of ACGIH for a medium workload category (75% work, 25% rest). Ideally, every area in each division requires individuals to work for 50% of the time and rest for 50% of time for each working shift. Keyword: Heat stress, heart rate measurement, palm oil mill industry, physiological changes Introduction Palm oil mills (PO) are one of the main work places open to high heat exposure. PO process involves the physical extraction of palm products crude palm oil and palm kernels from fresh fruit bunches (FFB). Almost all processes in PO involve high temperature. Heat stress may be defined as aggregate of environmental and physical factors causing total heat load imposition on human body 1. Whenever there is heat stress imposed on human body, it cause heat strain and other physiological reactions such as increased sweat production, higher body core temperature(bct) and increased heart rate(hr) 2 in body. Under extreme conditions, heat strain may cause health problems, such as heat cramps, heat exhaustion, heat syncope, heat rashes and heat stroke 3, 4.Therefore, the aim of this study is to determine the level of heat exposure and its effect on physiological changes among PO workers. At the same time, the outcome of this study will hopefully serve as a tool for employers to analyze and assess the associated risk in order to apply suitable control measures for extreme heat condition. Author for correspondence uvea_2000@yahoo.com Methodology Study design The study was conducted in two PO at Kota Tinggi, Johor, Malaysia. PO were divided in nine divisions(divs.) namely loading ramp, sterilization, thresher, kernel, press, production room, engine room, boiler room and workshop. Seventyfour workers from production division were selected as respondents. Case study subjects were considered with parameters like age (range:15-64 yrs), years of employment( > 6 months), heat intensity(temp. in workplace), health status(body mass index-bmi). Procedure Environmental parameters in selected work divisions (divs.) were measured to evaluate heat stress in subjects. Metabolic rate (MR) were estimated for specific working time duration in different divs. of PO Wet Bulb Globe Indoor Temperature (WBGTin) and metabolic workload were measured in six divs. (Sterilization, press, kernel, production room, engine room, boiler room). Area Heat Stress Monitor (QUESTEMP 34) was used to measure WBGTin ( C) and relative humidity(rh in % 7.. The Wet Bulb Globe Temperature (WBGT) for indoor area without direct sunlight was calculated as follows 8 : WBGT = 0.7WB + 0.3GT (1)

2 BAHRI et al.: STUDY ON PHYSIOLOGICAL EFFECT ON PALM OIL MILL WORKERS 407 where WBGT, wet bulb globe temp. index;wb, wet bulb temperature;gt, globe temperature. Time-weighted average WBGT is calculated for exposure (8 hrs) as follows 8 : WBGT 1 t1 WBGT 2 t2...wbgt n t t t...t (2) where WBGT1 x t1 + WBGT2 x t WBGT 8 x t 8, WBGT values per hr; t 1 +t 2 +.t 8, duration of exposure per hr. The workload category is determined by averaging MR for tasks and then ranking them for light, moderate and heavy workload. Average MR is calculated as follows 9 : (M Average MR= 1)(t1) (M 2)(t2)... (Mn)(t t t...t where M, metabolic rate;t,time in minutes. 1 2 n n ) (3) Physiological parameters were measured using Omron Healthcare Blood Pressure Monitor (Omron T3). (BCT ( C) was measured using Instant Ear Thermometer (Omron MC510). Measurements were taken, after 2 hrs and 8 hrs of working respectively. Readings were taken three times and average value was considered as final reading. The information of physiological disorders due to heat exposure were obtained from selected workers through questionnaire. Personal information of workers namely socioeconomic background, their risk factor history of heat exposure and other information relating to heat stress were also been collected in questionnaires. Data analysis All data gathered for this study were analysed using Statistical Package for Social Sciences (SPSS). Demographic data were analysed using descriptive analysis. Normalization on data was performed before analysis. Independent t-test was conducted to compare statistical means of two PO. One-way ANOVA was carried out to determine the mean differences in three work shifts namely before, during and after work. Pearson correlation test was performed to identify correlation between BCT and physiological changes. Multi linear regression was performed to determine the relationship between the BCT and contributing factors. Results and Discussions Socio-demographic data respondent All the respondents are Malaysian, Malay and male in the age group between 20 to 60 years old. Among the seventy-four respondents, majority of them were 41 to 50 (37.8%) years old. Most of them (78.4%) had completed education until secondary school and had a normal BMI (66.3%) in the range of 18.5 to 24.9 kg/m 2. Besides, majority of the respondents have been working for more than 2 years (87.8%). Half of them had income in the range RM 1000 to RM 2000 (58.1%). Heat stress index (WBGTin), metabolic workload and prevalence of heat stress and health complaints The heat stress index, metabolic workload & prevalence of heat stress and health complaints for two PO are shown in Table 1 and Table 2. Results showed that five divs.in PO had high WBGTin, which caused extreme heat conditions. The boiler div. of OP1 had the highest temp.(37.97 o C). The press div. of OP 2 had the lowest temperature (27.92 o C). Average WBGTin for OP1 and OP2 was o C and o C respectively, which is above the recommended Table 1 WBGTin, Wetbulb, Globe temperature and classification of work values among palm oil (OP) mills 1 & 2 Section WBGTin Wetbulb Globe temperature Metabolic workload (kcal/hour) Sterilizer OP Sterilizer OP Press OP Press OP Kernel OP Kernel OP Oil room OP Oil room OP Boiler OP Boiler OP Engine room OP Engine room OP Table 2 Prevalence of heat stress health complaints among palm oil mill workers Symptoms Yes (%) No (%) Fatigue 74 (100) 0 (0) Headache 59 (79.7) 15 (20.3) Nausea 7 (9.5) 67 (90.5) Uncoordinated muscle 16 (21.6) 58 (78.4) Dizziness 13 (17.6) 61 (82.4)

3 408 J SCI IND RES VOL 74 JULY 2015 ACGIHTLV level of 28.0 o C. Metabolic workload of respondents in medium work category was kcal/hr in respect to the ACGIH 10 level. Hence, the overall heat exposure levels in all divs. of two PO were found unsuitable for l working duration of 8 hrs a day. This study also found that WBGTin value exceeded the limit of the ACGIH for a workload in medium category (75% work, 25% rest). Ideally, every worker in each div. required to work for 50% of time and rest for 50% of time in each working shift. Physiological parameters for before shift, after 2 hrs and 8 hrs Results showed evidence of increasing mean values for BCT, systolic and diastolic BP and HR after 2 hrs and after 8 hrs respectively (Table 3). Difference of BCT after 2 hrs and 8 hrs There was significant increase in BCT after 2 hrs and 8 hrs (Table 3). Generally, human body maintains a fairly constant internal temperature, even when it is exposed to varying environmental temperatures 11.Work rate is most important factor for determining heat generation in core body 12. Previous research 13 proved that when a person performs heavy physical labour, MR increases, along with internal heat. It was also stated that humans maintain an average BCT of 37 +/- 0.5 degree Celsius 14. This study indicates that the measurement of BCT is a good sign to show the effect of thermoregulation in the body. Difference of systolic and diastolic BP, after 2 hrs and after 8 hrs There was a significant increase (p<0.001) in systolic and diastolic BP during 2 hrs and 8 hrs in comparison with before working state (Table 3). This increment was due to exposure in high temperature leading to increased blood viscosity 15.Previous research 15 also stated that acute heat exposure lead to increased blood flow in skin at expense of blood flow in other tissues 16. Most studies indicated that an increase in blood volume leads to an increase systolic and diastolic BP 17. Difference of heart rate, after 2 hrs and after 8 hrs ANOVA test determined significant difference (p<0.001) in HR between 2 hrs and 8 hrs of working shift in comparison with before working shift (Table 3). HR may be used as a gauge to determine heat exposure and metabolic workload 18. HR is also a valuable guide in assessing health hazards for workers exposed to heat stress 19. HR provides an important guideline in evaluating dangerous occurrences related to heat stress of workers 20. HR was found in range of beats per min.in this study.majority of workers in PO worked for more than 6 months and so they acclimatized themselves well within the environment. When exposure to heat takes place over an extended period of time in workplace, a process of physiological adaptation called acclimatization occurs 21.This is manifested as a reduction in HR and BCT at expense of increased sweating.the daily average HR should be less than 100 beats per minute for a moderate workload 22. While performing physical activity, HR increases in order to quickly deliver oxygen where it is needed 23. Increased volume of blood during physical activities causes high HR. In determining the prevalence of heat stress, it was found that the lowest heat stress prevalence (13.5%) was in press div. This was due to the location Table 3 Statistics of physiological parameters (BCT, diastolic BP, systolic BP and HR) Variables N=74 Mean ± SD Range p F BCT(before shift) ± 0.33 o C BCT (after 2 hours) ± 0.35 o C * BCT (after 8 hours) ± 0.25 o C Systolic BP (before shift) ± 1.76 mm Hg * Systolic BP (after 2hours) ± 1.52 mm Hg Systolic BP (after 8 hours) ± 1.87 mm Hg Diastolic BP (before shift) ± 1.37 mm Hg * Diastolic BP (after 2hours) ± 1.25 mm Hg Diastolic BP (after 8 hours) ± 1.64 mm Hg HR (before shift) ± 2.36 bpm * HR (after 2hours) ± 1.74 bpm HR (after 8 hours) ± 1.69 bpm 83 90

4 BAHRI et al.: STUDY ON PHYSIOLOGICAL EFFECT ON PALM OIL MILL WORKERS 409 of the div. with good ventilation system. Air circulation by fans to reduce heat was also found in this div. The highest heat stress prevalence was in the boiler div. (21.6%), because of the work process involved in enclosed area (unventilated) in comparison with other divs. Correlation between BCT and physiological parameters (systolic BP, diastolic BP, and HR) Results showed that there was weak correlation (30%) between the BCT and systolic BP after 2 hrs (r=0.296, p=0.011), BCT and systolic BP after 8 hrs (r=0.247, p=0.034) and BCT and HR after 8 hrs (r=0.325, p=0.005).the weak correlation could be due to the need to stop production intermittently in order to load FFB into the ramp section. The whole process takes one hr before FFB goes for next processing. Previous researchers stated that blood flow increased with increase in BCT in order to stabilize the internal body environment 24. Relationship between BCT and contributing factors among workers Results of linear regression analysis to determine the relationship between body core temperature and contributing factors age, BMI, employment yrs., systolic and diastolic BP, duration of exposure and WBGTin. There was no significant difference in the relationship between body core temperature after 2 hrs and 8 hrs. Respondents had a short break for water intake during 2 hrs to 8 hrs. Maintaining constant water intake may reduce body water loss and maintain BCT and fluid balance in body 27. All respondents were working in OP for over 6 months, which is a sufficient duration of heat exposure for adaptation of workers body. Conclusion Workers in PO were undergone to moderate heat stress during the study period. Average BCT, systolic and diastolic BP and HR did not reach an unacceptable level of physiological strain. Furthermore, a weak correlation was found between BCT, systolic BP and,hr. Overall heat exposure levels in all divs. in two PO were unsuitable for working duration of 8 hrs a day. Workload may be reduced to 50 % or regular break intervals needed to provide for PO workers.po employers should provide continuous training and heat control programmes to workers for basic understanding of heat effects on body for preventing heat-related illnesses. Acknowledgement This study was approved by Faculty of Medicine and Health Sciences Ethic Committee (Reference No:UPM/FPSK/PADS/T7-MJKEtikaPer/F01 (JKK (U) _Dis (11)18) which protects all confidential information regarding PO workers. This research was funded by the Research University Grant Scheme (RUGS) Initiative Vote Number: , faculty of Environment and Occupational Health, Universiti Putra Malaysia and Long-Term Research Grant Scheme (LRGS) Vote Number: , Ministry of Education Malaysia. Finally authors acknowledge volunteering involvement of Felda Palm Oil Mill and workers. References 1 Alpaugh E & Hogan TJ, Temperature extremes in Barbara, Fundamental of Indus Hyg, 3rd edn, (USA: National Safety Council),(1992) Rodahl K, Occupational Health Conditions in Extreme Environments, Annals of Occup Hyg,47(3)(2003) David RB, Core concepts in Physiology thermoregualtion: Regulation of heat balance in the body (New York: Lippincott-Raven) Baker D W, Thermal characteristics of clothing esembles for use in heat stress analysis, Am Indus Hyg Assoc J, 60 (1999) Crockford GW, The thermal environment, in Occup Health Pract, 2 nd edn, edited by Schilling R S F (London: Butterworths),(1981) Logan W & Bernard P, Heat stress and strain in aluminium smelter, Am Indust Hyg Assoc J, 60 (1999) Questemp34 Thermal Environment Monitor, Operator's Manual(USA: Quest Technologies) Criteria For A Recommended Standard Occupational Exposure to Hot Environment. (Department of Health and Human Services, Washington) Threshold Limits Values and Biological Exposure Indices for 2001, in Am Conf Gov Indus Hyg (ACGIH of Cincinnati, Ohio) 21 September Threshold Limit Values for Chemical Substance and Physical Agents and Biological Exposure Indices, in Am Conf Gov Indus Hyg(ACGIH of Cincinnati, Ohio) 1 March Gupta A K, Indus Safety and Environ (Laxmi Publications, New Delhi),(2006) Berry C, A Guide to Preventing Heat Stress and Cold Stress (N.C Department of Labor Occupational Safety and Health Division, North Carolina) Roffey D M, Exercise Intensity, Exercise Training and Energy Metabolism in Overweight and Obese Males, Ph D Thesis, Queensland University of Technology, Queensland, Australia, Heat and Cold : How does Human Body Regulate Temperature (University of Iowa) Kunst A E, Outdoor air temperature and mortality in the Netherlands : A time series analysis, Am J Epidemiol, 137:3 (1993)

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