Blood concentrations of lead and mercury in British Columbians (2009-2010)

Abstract

Background and Purpose: Adverse effects of lead and mercury on human health due to environmental and occupational exposures require a public health attention. These metals can cause severe harm to vulnerable populations such as children and pregnant women. The probability of chronic and harmful exposure is higher in occupational settings. Monitoring the levels of these two metals in blood is an important tool to identify and quantify exposure to these metals in the environment. Monitoring data provides vital information required for management of health risk posed by these metals. The purpose of this study was to perform a comparative analysis of blood lead levels and blood mercury levels within the province of British Columbia on the health services data obtained from BC Centre of Disease Control. The primary objective was to compare the levels of lead and mercury in blood among different health authorities of British Columbia. The secondary objective was to compare the levels of lead and mercury among different age groups and gender. Methods: The blood lead and mercury concentrations used for the analysis were provided by Environmental Health Services at the British Columbia Centre for Disease Control (BCCDC). The data comprised of blood analyses that were ordered by physicians during the period of 2009-2010 for reasons not disclosed. Access to this data was provided by Dr. Reza Afshari with the permission of Dr. Tom Kosastsky for the completion of this project only. Statistical analysis of data was performed using Microsoft Excel 2013 and SAS University Edition Analytic Software. Various descriptive and inferential statistical tests were performed on the data to determine the differences of blood mercury and lead levels among different genders, Health Authorities and age groups. Results: The levels of blood mercury and lead concentrations were not significantly different in males and females in province (p-value 0.5543 for mercury; p-value 0.5336 lead). However, it was found that blood levels of lead were higher in Interior Health and “Unknown” category (p<0.02), while blood mercury levels were significantly higher in coastal health authorities (highest in Vancouver Coastal Health Authority, followed by Fraser Health Authority and Vancouver Island Health Authority) (p<0.001). For both toxic metals, levels were highest in age group of 50 and above. (p<0.0001 for mercury, p<0.02 for lead). Conclusion: The statistical analysis of lead and mercury data was useful in characterizing the exposure among Health Authorities, age and sex of the people tested in province of British Columbia. Analysis of mercury data has generated clear patterns inferring association between coastal Health Authorities and elevated mercury levels. Vancouver Coastal Health had highest median mercury levels 4.02 μg/L higher than other health authorities (p<0.0001). Analysis of lead data established a pattern among physicians suggesting that they are more likely to order a test if the patient is under 18 years of age. Median levels were found to be highest in Interior Health Authority and “Unknown”