Assessment of Levels of Selected Heavy Metals among Industrial Workers and Related Occupational Health Effects in the City of Nairobi and Athi River Township in Kenya

Citation:
Were FH. Assessment of Levels of Selected Heavy Metals among Industrial Workers and Related Occupational Health Effects in the City of Nairobi and Athi River Township in Kenya. Kamau GN, Shiundu PM, eds. Nairobi: University of Nairobi; 2013.

Thesis Type:

PhD thesis

Abstract:

The study assessed the concentrations of heavy metals among factory workers (N = 282) and their related adverse health effects in Nairobi and Athi River Township in Kenya. Sets of whole blood, spot urine, scalp hair and personal breathing zone air samples were collected from these workers in various sections of 6 different plants, and analysed for cadmium (Cd), lead (Pb), nickel (Ni) and chromium (Cr) levels using atomic absorption spectrophotometery. This method of analysis was validated using certified reference whole blood samples, BCR®-635 and BCR®-636. The results indicated mean airborne Pb levels ± standard deviation (SD) in production sections as follows: 183.2 ± 53.6 ug/rrr' in battery recycling, 133.5 ± 39.6 ug/m' in battery manufacturing, 126.2 ± 39.9 ug/rrr' in steel and scrap welding, 76.3 ± 33.2 ug/nr' in paint manufacturing, 27.3 ± 12.1 ug/rn" in leather and tannery, and 5.5 ± 3.6 !!g/m3 in the pharmaceutical plant. The average airborne Pb levels in production sections were significantly high (P < 0.05) when t·.... .• compared to those in their respective office areas, which was: 23.9 ± 6.9 ug/rrr', 18.8 ± 1.6 ug/m", 23.5 ± 5.8 ug/m:', 13.8 ± 3.0 ug/rn", 8.0 ± 2.7 ug/m" and 2.1 ± 0.2 ug/nr'. In all cases, the average airborne Pb levels in production areas markedly exceeded the U.S. Occupational Safety Health Administrations' Permissible Exposure Limit of 50 ug/rrr' ~ over an 8-hour Time-Weighted Average except for leather and tannery, and pharmaceutical plant. Blood lead (BPb) levels of all employees correlated positively (r = 0.86) with airborne Pb. All the determined mean BPb values in production workers exceeded 30 ug/dl, proposed by of the American Conference of Governmental for Industrial Hygienists (ACGIH) biological exposure indices (BEls), except for employees in leather and tannery, and pharmaceutical plant. Similarly, levels of Cd, Ni and Cr in the ambient air correlated positively (r = 0.99 Cd, 0.89 Ni and 0.84 Cr, N = 282) with those in the urinary samples. The production areas of steel and scrap welding plant had the highest mean levels of 0.13 ± 0.05 ug/rrr' Cd and 10-:-3±4.3 ug/rrr' Ni in the breathing zone air compared to those in the other plants. In this* facility, 50% (20 of 40) and 27.5% (11 of 40) of employees had urinary Ni and Cd levels that exceeded the ACGIH BEls. The average airborne Cr levels of 23.4 ± 11.6 ug/rrr' were highest in production areas of leather and tannery industry, where urinary mean Cr levels of 35.2 ± 12.1 ug/g exceeded the BEIs. Nearly 71% (22 of 31) and 27.5% (11 of 40) of leather tanners and steel and v scrap welders, respectively had urinary Cr levels that exceeded this limit. A positive correlation of r = 0.55 Cr; 0.61 Pb; 0.58 Cd and 0.30 Ni was also observed in the levels between these metals in the ambient air and hair samples. The relationship between levels of heavy metals in the hair and other biomarkers of exposure further indicated correlation coefficient values (r) of 0.57 for urinary-Cr; 0.51, urinary-Cd; 0.21, urinary- Ni; 0.59, blood-Pb; and 0.42 for blood-Cd. The results also established that a high proportion of steel and scrap welders (47.3%, N 19), battery recyclers (39%, N = 16) and battery manufacturers (37.5%, N = 15) had hypertensive range of blood pressure with high incidences of cardiovascular diseases and related symptoms, which were associated with significantly high levels of Pb and Cd. Almost 10.7% of production workers (N = 233) were anaemic, which was associated with elevated levels of BPb. Leather tanners (48.3%, N = 15) and steel and scrap welders (47.5%, N = 19) had high prevalence of respiratory illnesses that were marked by severely reduced forced' vital capacity (FVC) .' . and forced expiratory volume of air in thi -(l.i;t second (FEV i). These were indication of airway obstructions. It was further observed that leather tanners (41.9%, N = 13) and steel and scrap welders (40.0%, N = 13) had high occurrences of dermatological conditions that manifested in the form of rashes and itching and which were associated with elevated airborne levels of Cr and Ni.

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