F.C. Eloff

International guidelines for the in vivo assessment of skin properties in non-clinical settings: Part 2. transepidermal water loss and skin hydration

There is an emerging perspective that it is not sufficient to just assess skin exposure to physical and chemical stressors in workplaces, but that it is also important to assess the condition, i.e. skin barrier function of the exposed skin at the time of exposure. The workplace environment, representing a non‐clinical environment, can be highly variable and difficult to control, thereby presenting unique measurement challenges not typically encountered in clinical settings.

DNA damage and repair detected by the comet assay in lymphocytes of African petrol attendants : a pilot study

Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxic and carcinogenic effects. The single-cell gel electrophoresis assay (comet assay) is a method highly sensitive to DNA damage induced by environmental and occupational exposure to carcinogenic and mutagenic agents. The aim of this study was to evaluate the level of exposure of petrol attendants to petrol VOCs and also to determine their effect on DNA damage and repair in lymphocytes of African petrol attendants. The exposed group consisted of 20 subjects, randomly selected from three petrol stations. A control group of 20 unexposed subjects was also chosen and matched for age and smoking habits with the exposed group. Sorbent tubes were used to assess personal exposure of petrol attendants. The comet assay was used to investigate the basal DNA damage and repair capacity in isolated lymphocytes of petrol attendants and unexposed subjects. Blood samples were taken from the petrol attendants at the end of their 8-h working shift and also from the unexposed subjects. The petrol attendants were found to be exposed to levels of petrol VOCs lower than the South African occupational exposure limit for constituent chemicals. A significant relationship was found between the volume of petrol sold during the shift and the average concentrations of benzene, toluene and the total VOCs measured. However, relative humidity had a negative correlation with the average concentrations of benzene, toluene, xylene and the total VOCs. Significantly higher basal DNA damage was observed with the exposed group compared to the unexposed group. The period of exposure influenced the level of DNA damage and the calculated repair capacity. Smoking and age had a significant influence on the level of DNA damage. DNA repair capacity was delayed in smokers of both exposed and unexposed group.

Flow Cytometric Analysis of the Oxidative Status in Human Peripheral Blood Mononuclear Cells of Workers Exposed to Welding Fumes

Flow cytometry is a simple analytical technique that identifies, counts, and characterizes cells. The oxidative status of cells is influenced by many exogenous sources, such as occupational exposure to welding fumes. This study evaluated flow cytometry as a method to determine the oxidative status of male welders (n = 15) occupationally exposed to welding fumes. Flow cytometric analysis of reactive oxygen species (ROS) was carried out in peripheral blood mononuclear cells (PBMC) by using the probe 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA). Lipid peroxidation was measured by the decrease of fluor-DHPE fluorescence and intracellular glutathione (GSH) levels by using mercury orange. All of the parameters were also observed under a confocal microscope. The oxidative stress ratio was calculated from the oxidative damage and the antioxidant capacity to give an accurate account of the cellular oxidative status. ROS and lipid peroxidation levels were elevated by ∼ 87% and ∼ 96%, respectively, and GSH levels lowered ∼ 96% in PBMC of workers exposed to welding fumes compared with non-exposed controls. The oxidative stress ratio was significantly higher (p < 0.001) in the exposed group. Flow cytometry can be useful for the measurement of cellular oxidative stress in somatic cells of workers exposed to welding fumes and other occupational settings. Calculating an oxidative stress index may be useful in predicting disease outcomes and whether preventative control measures are efficient.

Prolactin, testosterone and cortisol as possible markers of changes in cardiovascular function associated with urbanization

People living in large informal settlements in South Africa showed a significant increase in cardio/cerebrovascular disease. This study was undertaken to compare the cardiovascular and endocrine parameters of urbanized and rural black female and males. The hormone levels such as prolactin, cortisol and testosterone may also change with urbanization and could make a contribution to the high rate of hypertension. For this study, 1202 black subjects were selected from 37 randomly selected rural and urbanized settlements. Resting blood pressure was recorded with a Finapres apparatus. Cardiac output, stroke volume, heart rate, total peripheral vascular resistance and compliance had been obtained with the Fast Modelflow software program. An acute laboratory stressor (hand dynamometer exercise) was applied to challenge the cardiovascular system and the measurements were repeated. Blood sampling was done and hormone levels were determined by biochemical analyses. For females, significant lower levels of cortisol were found in the urban strata in comparison with the rural strata. The testosterone levels were significantly lower and the prolactin levels significantly higher for females in the informal settlements compared with the rural strata. It is noticeable that most cardiovascular parameters showed the highest changes with the application of the stressor in the informal settlement strata and the lowest in people living on farms for both male and female. The prolactin levels in males are significantly higher in the informal settlement stratum. Subjects living in informal settlements showed a noticeable endocrine pattern of ongoing stress that can be associated with changes in the cardiovascular parameters with urbanization. This can partly explain the reported high rate of cardio/cerbrovascular disease in black South Africans living in informal settlements.

International guidelines for the in vivo assessment of skin properties in non-clinical settings: part 1. pH

Skin surface pH is known to influence the dissolution and partitioning of chemicals and may influence exposures that lead to skin diseases. Non‐clinical environments (e.g. workplaces) are highly variable, thereby presenting unique measurement challenges that are not typically encountered in clinical settings. Hence, guidelines are needed for consistent measurement of skin surface pH in environments that are difficult to control.

In vitro permeation of platinum and rhodium through Caucasian skin

During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace.

In vitro permeation of platinum through African and Caucasian skin.

The majority of the South African workforce are Africans, therefore potential racial differences should be considered in risk and exposure assessments in the workplace. Literature suggests African skin to be a superior barrier against permeation and irritants. Previous in vitro studies on metals only included skin from Caucasian donors, whereas this study compared the permeation of platinum through African and Caucasian skin. A donor solution of 0.3 mg/ml of potassium tetrachloroplatinate (K₂PtCl₄) dissolved in synthetic sweat was applied to the vertical Franz diffusion cells with full thickness abdominal skin. Skin from three female African and three female Caucasian donors were included (n=21). The receptor solution was removed at various intervals during the 24 h experiment, and analysed with high resolution inductively coupled plasma-mass spectrometry (ICP-MS). Skin was digested and analysed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Significantly higher permeation of platinum through intact African skin (p=0.044), as well as a significantly higher mass of platinum retention in African skin in comparison with Caucasian skin (p=0.002) occurred. Significant inter-donor variation was found in both racial groups (p<0.02). Results indicate that African workers have increased risk of dermal permeation and therefore possible sensitisation caused by dermal exposure to platinum salts. These results are contradictory to limited literature suggesting a superior barrier in African skin and further investigation is necessary to explain the higher permeation through African skin.

Lung function, inflammation and cardiovascular mortality in Africans.

The link between impaired lung function and cardiovascular outcome is well established in European and American populations. It is possible that this association may be driven by a systemic spillover of inflammation occurring within the lungs. As several studies have found an increased level of inflammatory markers in African populations, we aimed to establish the contribution of lung function in predicting all‐cause and cardiovascular mortality in Africans, whilst taking inflammatory markers into account.

South African and international reference values for lung function and its relationship with blood pressure in Africans.

BACKGROUND In South Africa respiratory diseases are highly prevalent, with cardiovascular disease being a manifestation. However, international reference values for lung function are commonly used, which may not be appropriate to correctly identify reduced lung function. An inverse relationship exists between lung function and blood pressure (BP) but is not investigated extensively in black South Africans. METHODS We included 2010 Africans from the PURE (Prospective Urban Rural Epidemiology) study (aged > 35 years) in the North West Province. Spirometry was performed and predicted values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were calculated from South African, European and United States prediction equations. RESULTS With the exception of the European predicted values, all other predicted mean FEV1 and FVC were above 80%. South African reference values displayed the highest percentages of the predicted values for FEV1 and FVC (87.9 and 99.7%, respectively.) BP increased from quintiles five to one for both FEV1 and FVC, (p for trend <0.001). After adjustment the differences remained (p<0.05). CONCLUSIONS South African reference values yielded higher percentages of predicted FEV1 and FVC values than European and US equations suggesting that South African prediction equations may be more useful when investigating lung function in black South Africans. Elevated BP is related to reduced lung function, highlighting the importance in managing both respiratory- and cardiovascular disease.