Date Published: July 23, 2019
Publisher: F1000 Research Limited
Author(s): Puleng Matatiele, Lerato Mochaki, Bianca Southon, Boitumelo Dabula, Poobalan Poongavanum, Boitumelo Kgarebe.
This report is an overview of requests for biological and environmental monitoring of hazardous chemicals, submitted to the National Institute for Occupational Health, Analytical Services Laboratory for testing from the years 2005 to 2015. The report discusses the nature of tests requested and implications for workers’ health and environment, as well as potential impact of the uncertainties associated with monitoring of hazardous chemicals. This is a retrospective, descriptive, qualitative and quantitative audit of all samples received and tests performed retrieved from records of analysis by the laboratory. The study sample consisted of 44,221 samples. The report indicates that throughout the interrogation period the demand for biological monitoring was higher than that for environmental monitoring, with more requests for toxic metals than organic pollutants. Toxic metal testing was highest for mercury, followed by manganese, lead, aluminium and arsenic. The highest number of tests for organic pollutants was conducted for pesticides followed by toluene and xylene. The study has also revealed that the scope of tests requested is rather narrow and does not reflect the broad spectrum of
South Africa’s industrial diversity. Having identified possible reasons for underutilization, a number of reforms that could enhance the laboratory’s performance have been addressed.
Humans are exposed to hazardous chemicals in a variety of ways; mainly through diet and through the air that we breathe (indoor, outdoor and occupational). Occupational exposure can occur through inhalation, absorption through the skin or ingestion, with the inhalation of vapours, dusts, fumes or gases being the route of highest exposure
1. Both biological and environmental monitoring can help in assessment of exposure to specific chemicals, characterization of exposure pathways and potential risks and their mitigation, and thus serve as elements of health surveillance that can be used in the assessment of the risks to health as an integral part of occupational and environmental health and safety programmes. Thus, the three-pronged prevention of diseases due to toxic agents in the general or occupational environment involves both environmental and biological monitoring, as well as health surveillance
2. In the occupational context, environmental monitoring entails characterization and monitoring of the quality of the environment in preparation for environmental impact assessment
4. As a result, environmental monitoring is critical to understanding whether the quality of the environment is getting better or worse, and allows for the removal of a worker from a contaminated environment before adverse health effects are experienced. Biological monitoring in the workplace involves the detection of biomarkers in biological samples (e.g., breath, urine, blood, hair, etc.) from workers, and the comparison to reference values
6. Guidelines for chemical monitoring strategies have established that monitoring is necessary if there is reason to believe that a hazard exists or may develop in the workplace
7. Thus, monitoring and surveillance are valuable tools enabling identification and tracking of exposures to hazards in the environment and their related health implications. It is through the results of monitoring and surveillance programs that it becomes possible for authorities to make sound and effective public and environmental health policies and interventions, as well as enabling employers to measure the efficacy of control measures.
Table 1 shows the total number of tests performed for the analysis of both toxic metals and organic pollutants per year for the period 2005 to 2015 at NIOH, the results of which are
available on OSF10. Generally, there were more requests for analysis of toxic metals than for that of organic pollutants (
Figure 1). In addition, analysis of both toxic metals and organic pollutants exposure grew steadily from 2005 to 2010, after which the laboratory saw a decline in the number of test requests. With regard to individual toxic metals tests,
Figure 2a shows that the demand for inorganic mercury testing had the highest frequency, followed by manganese and lead. The most common matrix tested was blood followed by urine, water, and serum (
Figure 2b). Organic pollutant monitoring results (
Figure 3) show that the highest number of tests was conducted for pesticides, followed by phenol, toluene and xylene. These pollutants are as a result of activities mainly from the agriculture (pesticides) and petrochemical/motor and mining (phenol, toluene and xylene) industries. Even though no data has been shown in this study, NIOH has also received requests for toxic chemical testing in a wide variety of samples, including nails, hair and unidentified powders and liquids. Also not shown are requests from clinicians for therapeutic drug monitoring and forensic toxicology assessment.
Assessment and characterization of the body-burden of hazardous chemicals and the potential health risks thereof is a key strategy for providing a scientific basis for prevention via exposure reduction and motivating action especially in occupational settings. The increase in bio-monitoring versus environmental monitoring, as seen in our results, confirms some literature findings, which report that exposure assessment has shifted from pollutant monitoring in air, soil, and water towards personal exposure measurements and bio-monitoring
11. The decline in the number of tests requested from NIOH Analytical Services laboratory in latter years is noted. The decline is suggestive of an underutilized resource, which could have been as a result of various reasons, including:
Complete data regarding the number of tests for each metal and organic compound are available on OSF:
http://doi.org/10.17605/osf.io/fh8z710. Data are displayed per year and consolidated.