Инноваци - Шинэ Санаа, Шинэ Нээлт, 2008, 1(5-1)
Baseline study for intervention to reduce tannery worker exposures in U laanbaatar, Mongolia
( Судалгааны өгүүлэл )
1-Department of Epidemiology and Biostatistics, School of Public Health, Health Sciences University of Mongolia,
2-Department of Preventive Medicine, School of Public Health, Health Sciences University of Mongolia, Ulaanbaatar
3-Municipal Inspectorate Agency,, Ulaanbaatar City Government,
4-Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta USA
Абстракт
Totally 34 tanneries are located in the city and tanneries use trivalent chromium as a tanning agent. The overall objective of the study is to help minimize the human and environmental health impacts of small and medium-sized tanneries in Ulaanbaatar.
Convenience sample of 16 small and medium-sized tanneries 8 each assigned to the intervention and control groups. Urine sample collected in 250 mL bottles and their own samples after receiving a 5-minute face-to-face. Urine samples were for total chromium and creatinine at the KOSHA lab. Mean differences in PPE-wearing behavior and biological Cr levels from baseline to intervention will then be compared between the intervention and control groups to provide a quantitative assessment of the effectiveness of the intervention.
Introduction
Ulaanbaatar city is an industrial area, totally 34 tanneries are located in the city and eight of them discharge their untreated effluents either to the central wastewater treatment plant (CWWTP) or directly into the Tuul River, the main river in Ulaanbaatar (Lkhasuren 2005, PREGA 2004). Everyday 30,000 hides are tanned in Mongolian factories using chromium-based technologies. Mongolian leather tanneries use trivalent chromium [Cr(III III III )] as a tanning agent. Since tannery workers are directly in contact with or work near to chromium compounds, the potential health effects of such exposures merits investigation given knowledge about this substance.
The overall objective of the study is to help minimize the human and environmental health impacts of small and medium-sized tanneries in Ulaanbaatar. The intervention consists of basic training for tannery workers, managers, and owners on tannery workplace health and safety, as well as intensive follow-up technical assistance on specification and purchase of appropriate personal protective equipment (PPE). In a related 2005 pilot study, we found elevated urinary chromium in Ulaanbaatar tannery workers versus a control group of garment workers, and no significant difference among tannery workers by job.
Methods
Intervention group gets basic training and intensive follow up, but control group gets basic training. Primary outcome of intervention was the percent of time tannery workers wear task-appropriate PPE while performing specific tasks during the work day (used PPE % time)
Secondary outcome is total chromium concentration in worker urine sample.
Sample selection/recriutment
Convenience sample of sixteen small and medium-sized tanneries (small < 10 workers, medium 10 – 50 workers). Eight each assigned to the intervention and control groups. Tanneries not blinded as to their intervention or control status and 2-6 workers from each tannery randomly-selected from personnel rosters for observational data and biological sample collection. A recruitment target of 45 workers each in the intervention and control groups was set based on data collected in a pilot observational study of 36 workers in two tanneries conducted by trained field technicians in November 2006.Tannery owners and managers gave verbal consent for the collection of observational data, while individual workers gave written consent for biological sample collection
Baseline observational data were collected in 15-minute increments by trained researchers using standardized data collection forms.
Urine sample collected in VWR® TraceCleanTM 250 mL HDPE bottles (VWR International, Marietta, GA) and workers collected their own samples after receiving a 5-minute face-to-face instruction from a trained field technician. Field blank sample consisting of approximately 200 mL of Milli-Q® Ultrapure water (Millipore Corporation, Billerica, MA) in a TraceCleanTM sample bottle was collected for each day of field sampling. Blanks prepared in general laboratory at the Health Sciences University using water transported from Emory University (Atlanta, USA). Urine samples digested by nitric acid and analyzed for total chromium using Zeeman-correction GF-AA, were also analyzed for specific gravity and creatinine at the Korean Occupational Safety and Health Agency (KOSHA, Republic of Korea) laboratory.
Data analysis
- Response rates for observational data and urine samples collected calculated in MS Excel (Microsoft Corp, Redmond, Washington)
- Observational data analyzed in MS Excel; following statistics calculated for each worker:
– Used PPE % time = minutes actual used PPE/minutes should have used PPE
– Not used PPE % time =minutes not used PPE/minutes should have used PPE
– Not available PPE % time = minutes not available to use PPE/minutes should have used PPE
– Not applicable PPE % time = minutes not applicable to use PPE/minutes should have used PPE
- SAS (SAS Institute, Cary, North Carolina) used for urine data analysis; data were tested for normality/lognormality using the Shapiro-Wilk and Kolmogorov-Smirnov tests; two-sample t-tests used to test difference in mean log-transformed creatinine-adjusted urinary chromium between intervention and control workers
Results
Response rate for the intervention and control tanneries were 98 percent in intervention and 51 percent in control group.
The most common reasons for incomplete observational data collection were that some tanneries ended the work shift early once available hides were processed and that some owners requested technicians only collect data before or after lunch time instead of during the full shift.
There was no significant difference between the intervention and control workers with respect to used PPE % time of water resistant boots (Wilcoxon Rank Sum p=0.10), apron (Wilcoxon Rank Sum p=0.17), or face protection mask (Wilcoxon Rank Sum p=0.84). There was significant difference between groups with respect to time wearing protective gloves (Wilcoxon Rank Sum p=0.04). Control tannery workers used gloves more often on average. (Table 1)
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There was a statistically significant difference in baseline mean log creatinine-adjusted urinary Cr between intervention and control workers (two sample t-test, equal variances, p=0.0448). There was no statistically significant difference in baseline mean log creatinine-adjusted urinary Cr between control and intervention workers (two sample t-test, equal variances, p=0.1303) when dilute samples were excluded (n excluded = 1 in intervention group, 5 in control group). The urinary Cr for one intervention and two control group workers exceeded the American Council of Governmental Industrial Hygienists (2000) Biological Exposure Index (BEI) for Cr (10 ug/g creatinine) (Table 2).
Discussion
There was no significant difference between the intervention and control workers with respect to used PPE % time of water resistant boots (Wilcoxon Rank Sum p=0.10), apron (Wilcoxon Rank Sum p=0.17), or face protection mask (Wilcoxon Rank Sum p=0.84).
• There was no statistically significant difference in baseline mean log creatinine-adjusted urinary Cr between control and intervention workers (two sample t-test, equal variances, p=0.1303) when dilute samples were excluded (n excluded = 1 in intervention group, 5 in control group).
• This provides evidence that the tannery assignment (to intervention or control groups), although not random, was effective in producing two comparison groups with relatively similar workplace PPE-wearing behavior and Cr exposure characteristics.
• Observational and biological data will be collected in December-January 2007, after the intervention has been delivered to all tanneries in the intervention group.
• Mean differences in PPE-wearing behavior and biological Cr levels from baseline to intervention will then be compared between the intervention and control groups to provide a quantitative assessment of the effectiveness of the intervention.
Acknowledgments
This study was funded by grant number 103053-001 to the Health Sciences University of Mongolia from the International Development Research Centre (Ottawa, Canada). The authors thank the tannery employees, managers, and owners for their gracious participation and Dr. Ana Boischio of IDR IDR IDR C for her sustained advice and support.
Ном зүй
1. Agency for Toxic Substances and Disease Registry (ATSDR DR ). 2000. Toxicological Profile for Chromium. Accessed online on 13 February, 2006
2. Lkhasuren O, Riederer A, Galsandamba N, Ochir, C. 2006. Pilot study of chromium exposures in the Mongolian leather tanning industry [Abstract]. Epidemiology, 17(6)(Suppl):S184-S185.
3. Lkhasuren O, Namsrai G, Ochir Ch, Narantuya S, Reiderer A, Comparative study of the urinary chromium concentration among Tannery and Control workers, Journal of Health Sciences, Ulaanbaatar, 2006(4);117-120,
4. OD Consult Ltd. 2003. Reducing Environmental Pollution of the Mongolian Tannery Sector. [Proposal] Enterprise Restructuring Project-Phase II II . Supported by the Royal Netherlands Embassy - Beijing, Implemented by the German Development Cooperation
5. Occupational Safety and Health Aspects of Leather Manufacture, Guidelines and Recommendations for managers and supervisors of tanneries and effluent treatment plants, Regional programme office UNID UNID UNID UNID O. 2004
6. World Health Organization (WHO). 2005. Mongolia: Environmental Health Country Profile
2. Lkhasuren O, Riederer A, Galsandamba N, Ochir, C. 2006. Pilot study of chromium exposures in the Mongolian leather tanning industry [Abstract]. Epidemiology, 17(6)(Suppl):S184-S185.
3. Lkhasuren O, Namsrai G, Ochir Ch, Narantuya S, Reiderer A, Comparative study of the urinary chromium concentration among Tannery and Control workers, Journal of Health Sciences, Ulaanbaatar, 2006(4);117-120,
4. OD Consult Ltd. 2003. Reducing Environmental Pollution of the Mongolian Tannery Sector. [Proposal] Enterprise Restructuring Project-Phase II II . Supported by the Royal Netherlands Embassy - Beijing, Implemented by the German Development Cooperation
5. Occupational Safety and Health Aspects of Leather Manufacture, Guidelines and Recommendations for managers and supervisors of tanneries and effluent treatment plants, Regional programme office UNID UNID UNID UNID O. 2004
6. World Health Organization (WHO). 2005. Mongolia: Environmental Health Country Profile
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