Wells Utembe

The Globally Harmonized System (GHS) is a crucial framework for chemical hazard communication, especially in protecting workers from skin sensitizers. A critical assessment of the principles, issues, and challenges around classification of skin sensitization in GHS is warranted. Classification of dermal sensitizers relies on a weight of evidence (WoE) approach that incorporates human, animal, and non-test data. However, current testing methods have limitations in sensitivity, specificity, and predictive accuracy. Current test methods take into account the issue of potency and thresholds for sensitization. However, the focus on induction thresholds rather than induction and elicitation thresholds may create a gap in protecting already sensitized individuals since elicitation thresholds are in some cases lower than induction thresholds. While the sensitization process may take weeks or years, current test methods are largely acute in nature, potentially incapable of identifying all (chronic) sensitizers. Moreover, current methods used for classification of skin sensitizers only take into account the dermal route, whereas some chemicals may cause dermal sensitization through other routes, which presents a significant limitation, especially when considering non-animal testing methods. Finally, lack of UV irradiation in current methods may inadvertently miss potential photosensitizers, which may result in misclassification. Continuous refinement of testing methods and integrating novel approaches are essential to improve GHS classifications for skin sensitizers.

The province of Gauteng in South Africa has a rich history of gold mining, which has driven economic growth and urbanization. Gold mining has also created over 270 gold mine tailings (GMT), now surrounded by human settlements due to a housing shortage. These GMT pose a health risk as they harbor elevated uranium, which over time undergoes radioactive decay to produce radon, a known lung carcinogen. This study aimed to investigate the potential correlation between the proximity to gold mine tailings (GMT) and indoor radon concentrations in Gauteng’s residential dwellings. Volume activity of radon (VAR) inside 330 residential dwellings was measured in residential dwellings located proximally (2 km) to gold mine tailings using AlphaE radon monitors during winter. An interviewer-administered questionnaire was utilized to obtain data on factors that may influence indoor radon activities. Descriptive statistics and bivariate logistic regression analyzed the influence of proximity to gold mine tailings and dwelling characteristics on VAR. Furthermore, VAR was compared to the World Health Organization (WHO) radon reference level of 100 Bq/m³. Residential dwellings near gold mine tailings had significantly higher average indoor radon concentrations (103.30 Bq/m³) compared to the control group (65.19 Bq/m³). Residential dwellings proximal to gold mine tailings were three times more likely to have VAR beyond the WHO reference level of 100 Bq/m³. Furthermore, they had estimated annual effective doses of 2.60 mSv/y compared to 1.64 mSv/y for the control group. This study highlighted a concerning association between proximity to gold mine tailings and elevated indoor radon levels. Public health interventions prioritizing residential dwellings near gold mine tailings are crucial. Educational campaigns and financial assistance for radon mitigation systems in high-risk dwellings are recommended. Residents near gold mine tailings are encouraged to ensure continuous natural ventilation through frequent opening of windows and doors.

Radon is a known carcinogen, and the accurate assessment of indoor levels is essential for effective mitigation strategies. While long-term testing provides the most reliable data, short-term testing (STT) offers a quicker and more cost-effective alternative. This review evaluated the accuracy of STT in predicting annual radon averages and compared testing strategies in Europe (where long-term measurements are common) and the United States (where STT is prevalent). Twenty (20) studies were systematically identified through searches in scientific databases and the grey literature, focusing on STT accuracy and radon management. This review revealed several factors that influence the accuracy of STT. Most studies recommended a minimum four-day test for initial screening, but accuracy varied with radon levels. For low levels (95%) in predicting annual averages. However, accuracy decreased for moderate levels (approximately 50% success rate), necessitating confirmation with longer testing periods (3 months). High radon levels made STT unsuitable due to significant fluctuations. Seasonality also played a role, with winter months providing a more representative picture of annual radon averages. STT was found to be a useful method for screening low-risk areas with low radon concentrations. However, its limitations were evident in moderate- and high-level scenarios. While a minimum of four days was recommended, longer testing periods (3 months or more) were crucial for achieving reliable results, particularly in areas with potential for elevated radon exposure. This review suggests the need for further research to explore the possibility of harmonizing radon testing protocols between Europe and the United States.

Exposure to chemicals in many occupational and environmental settings has the capacity to significantly disturb the commensal microbiota that symbiotically reside in humans. However, much more is known about gut microbiota (GM) than lung microbiota (LM) due to the challenges of collecting LM samples. The advent of culture-independent methodologies has revealed the complex and dynamic community of microbes harbored by the respiratory tract. It is now being recognized that LM can directly impact immunity in a manner that can result in disease. Significant differences in community composition and diversity have been shown between the LM of diseased lungs and those of healthy subjects. Studies have linked LM dysbiosis with human diseases such as idiopathic pulmonary fibrosis, lung inflammation, chronic obstructive pulmonary disease (COPD), asthma, and lung cancer. However, it is not known whether LM dysbiosis initiates/promotes disease pathogenesis or is merely a biomarker of disease. Many chronic lung diseases often occur together with chronic GIT diseases in what is termed as the gut–lung axis. The LM also affects the CNS, in the bidirectional lung–brain axis, through a number of potential mechanisms that include the direct translocation of micro-organisms. Chemically induced LM dysbiosis appears to play a significant part in human diseases as has been shown to arise due to air pollution, cigarette smoking, and the use of chemical antibiotics.

The toxicity of engineered nanomaterials (ENMs) in vivo and in vitro has formed the basis of most studies. However, the toxicity of ENMs, particularly on the immune system, i.e. immunotoxicity, and their role in manipulating it, are less known. This review addresses the initiation or exacerbation as well as the attenuation of allergic asthma by a variety of ENMs and how they may be used in drug delivery to enhance the treatment of asthma. This review also highlights a few research gaps in the study of the immunotoxicity of ENMs, for example, the potential drawbacks of assays used in immunotoxicity assays; the potential role of hormesis during dosing of ENMs; and the variables that result in discrepancies among different studies, such as the physicochemical properties of ENMs, differences in asthmatic animal models, and different routes of administration.