The 28 th Asia Pacific Occupational Safety and Health Organization Conference, Seminar & Expo, Jakarta 8-12 Oct. 2013 Homocysteine as biological indicator for occupational lead exposure among industrial workers Shamsul B.S. 1 1 Department of Community Medicine, School of Medicine, University Malaysia Sabah, 88400 UMS Road, Kota Kinabalu, Sabah. What is homocysteine? Homocysteine is an amino acid, which is now considered a risk factor in several disease states. Elevated levels of homocysteine have been linked to increased risk of disease development and death from common conditions. 1
Homocysteine and health related problems Source : http://www.homocysteine.org.uk Source : www.diabetesjain.com 2
Throughout life the level of homocysteine in plasma increases in both males and females. Source : http://www.homocysteine.org.uk Lifestyle factors which increase homocysteine levels include: Diet - high alcohol intake and coffee consumption Smoking Lack of physical exercise and excessive stress Obesity Drugs and certain diseases also influence homocysteine metabolism Exposure to heavy metal (etc. lead)??? 3
Safe clinical guidelines Lead Poisoning Lead has no known biological function. There is no proven safe lower limit for lead. Lead Pb ++, competes with Ca ++, Fe ++ It is cheap, useful, easy to mine, therefore Lead is ubiquitous- in air, food, water, soil, ceilings etc. Leaded petrol means that all environmental dusts are high in lead-contaminating ceiling dust, topsoil, window wells etc. 4
Contribution of Sources Distribution of Lead 95% long bones. Binds into matrix. Released during osteolysis. 4% brain, liver, kidneys. 1% blood. Crosses placenta, foetal BBB is open 5
Children Pregnant women and developing fetus. Risk groups Specific occupational exposure Effects of lead exposure on young children Lowered IQ Learning disabilities Attention deficit and hyperactivity Other behavioral issues Impaired hearing Anemia Decreased growth 6
Health Effects of Lead Study objective This study aims to identify the relationship between lead exposure and homocysteine levels among the automotive component manufacturing factory workers. 7
Methodology Cross-sectional study design. Total 80 workers (40 lead exposed; 40 lead unexposed). Blood samples (finger-prick) and analyzed for blood lead using Atomic Absorption Spectrometry Graphite Furnace Model GBC 908AA. Homocysteine measured using ELISA Hcy Kit. Questionnaires were used to obtain demography information of respondents. Results Table 1: The comparison of blood lead and homocysteine between the exposed and comparative group Variable Median (IQR) Exposed (n=40) Range Median (IQR) Comparative (n=40) Range z value p value blood lead ( µg/dl) 3.82 (5.92) 0.68 to 17.95 2.98 (4.21) 0.08 to 11.96-1.178 0.035 * homocysteine level (µmol/l) 11.89 (2.13) 8.64 to 18.54 3.77 (1.86) 0.58 to 6.41-7.699 0.001 ** N = 80 ** Significant at p<0.01 * Significant at p<0.05 8
Results Table 2 : Spearman s Correlation between blood lead and homocysteine level. Variable Pb Blood (µg/dl) vs Homocysteine level (µmol/l) Exposed (n=40) Comparative (n=40) r value p value r value p value 0.049 0.764-0.053 0.743 N=80 Conclusions Blood lead concentration for both exposed group and the comparative group was not significant and extremely low. The concentration of homocysteine concentration was significantly higher among the exposed group compared to the comparative group. 9
Conclusions There was no significant correlation between blood lead concentration and homocysteine level among both the exposed group the comparative group. Anyways, there are other main factors which may contribute to the increase of homocysteine concentration in blood need to be considered. Main references 1. Lee YM, Lee MK, Bae SG, Lee SH, Kim SY, Lee DH. Association of homocysteine levels with blood lead levels and micronutrients in the US general population. J Prev Med Public Health. 2012 Nov;45(6):387-93. 2. Yakub M, Iqbal MP. Association of blood lead (Pb) and plasma homocysteine: a cross sectional survey in Karachi, Pakistan. PLoS One, 2010 Jul 5(7): e11706. 3. Ho RC, Cheung MW, Fu E, Win HH, Zaw MH, Ng A, et al. Is high homocysteine level a risk factor for cognitive decline in elderly? A systematic review, meta-analysis, and meta-regression. Am J Geriatr Psychiatry. 2011;19(7):607 617. 4. Schafer JH, Glass TA, Bressler J, Todd AC, Schwartz BS. Blood lead is a predictor of homocysteine levels in a population-based study of older adults. Environ Health Perspect. 2005;113(1):31 35. 5. Chia SE, Ali SM, Lee BL, Lim GH, Jin S, Dong NV, et al. Association of blood lead and homocysteine levels among lead exposed subjects in Vietnam and Singapore. Occup Environ Med. 2007;64(10):688 693. 6. Krieg EF, Jr, Butler MA. Blood lead, serum homocysteine, and neurobehavioral test performance in the third National Health and Nutrition Examination Survey. Neurotoxicology. 2009;30(2):281 289. 7. lora SJ, Mittal M, Mehta A. Heavy metal induced oxidative stress & its possible reversal by chelation therapy. Indian J Med Res. 2008;128(4):501 523. 8. Navas-Acien A, Selvin E, Sharrett AR, Calderon-Aranda E, Silbergeld E, et al. Lead, cadmium, smoking, and increased risk of peripheral arterial disease. Circulation. 2004;109:3196 3201. 9. Aamir M, Sattar A, Dawood MM, Dilawar M, Ijaz A, et al. Hyperhomocysteinemia as a risk factor for ischemic heart disease. J Coll Physician Surg Pak. 2004;14:518 521. 10.Rahbar MH, White F, Agboatwalla M, Hozhabri S, Luby S. Factors associated with elevated blood lead concentrations in children in Karachi, Pakistan. Bulletin of the World Health Organization. 2002;80:769 775. 11.Glenn BS, Stewart WF, Links JM, Todd AC, Schwartz BS. The longitudinal association of lead with blood pressure. Epidemiology. 2003;14:30 36. 12.Yakub M, Iqbal MP, Mehboobali N, Haider G, Azam I. Blood lead and plasma homocysteine in petrol pump workers in Karachi: Role of vitamins B6, B12, folate and C. J Chem Soc Pak. 2009;31:319 323. 10
Acknowledgement This research would not be able to be completed without assistance, guidance and support from institutional and many individuals. I would like to take this opportunity to acknowledge my research assistant Miss How Pai Sha, cause been sincere and patience together with me to accomplished this study. I am very grateful to Ms Siti Muskinah, Ms Amrina, Ms Safarina, Mr Saufi and Ms Rosalina for their assistance and guidance in the laboratory work. My thanks also go to the managers and respondents at the factory whom had allowed and assisted me in sample collection. Last but not list, funder for this research was University Research Grant from Ministry of Higher Education. 11