Skin and respiratory exposure to soluble lead, cobalt, nickel, copper, arsenic and silver at two South African precious metals refineries.

OBJECTIVES: Precious metals refinery workers are exposed to soluble platinum group metals (PGMs) during PGM-refining but may also be exposed to hazardous non-PGMs (Pb, Co, Ni, Cu, As and Ag) still present in the matte following base metals refining. The aim of this article was to report the skin and respiratory exposure of workers to soluble non-PGMs during PGM-refining. METHODS: Skin and respiratory exposure (of 40 workers at two precious metals refineries) were measured simultaneously over two consecutive shifts. Skin exposure was measured on the palm, wrist, neck and forehead using Ghostwipes™ and respiratory exposure was measured using the MDHS method 46/2 during which soluble metals were extracted using 0.07 M HCl and mechanical agitation, followed by ICP-MS analysis. RESULTS: The geometric means (GM) of average skin exposure to individual soluble metals on all anatomical areas was found in the order Cu (0.018 µg/cm2) > Ni (0.016 µg/cm2) > Pb (0.008 µg/cm2) > Ag (0.006 µg/cm2) > As (0.004 µg/cm2) > Co (0.0008 µg/cm2) with the palm being the highest exposed anatomical area. The order of the GM respiratory exposure was Pb (0.224 µg/m3) > Ag (0.201 µg/m3) > Cu (0.159 µg/m3) > As (0.079 µg/m3) > Ni (0.034 µg/m3) > Co (0.016 µg/m3) with exposure to As exceeding the South African occupational exposure limit (20 µg/m3) during concentrate handling (max 66.174 µg/m3). CONCLUSIONS: Workers were exposed to a mixture of toxic PGM and non-PGMs via the skin and inhalation. Exposure to these metals could lead to the development of diseases, such as contact dermatitis, occupational allergy, or occupational cancer. Non-PGMs must be included in hazardous chemical risk assessments and control strategies implemented at precious metals refineries.

Effectiveness of Personal Protective Equipment in Reducing Skin Exposure to Soluble Platinum.

OBJECTIVES: Various forms of personal protective equipment (PPE), including disposable coveralls and gloves, are used to help reduce skin exposure to soluble platinum in precious metals refineries. We aimed to investigate the effectiveness of PPE in reducing workers' skin exposure to soluble platinum. METHODS: Thirty precious metals refinery workers were divided into two groups according to their use of PPE and related procedures. Group A (n = 13) used disposable coveralls worn over standard overalls along with long-sleeved rubber gloves, while Group B (n = 17) used standard overalls only and surgical nitrile gloves. The skin (palm, wrist, neck, and forehead) and respiratory exposure of these groups to soluble platinum were concurrently measured (using Ghostwipes™ and MDHS 46/2, respectively) along with their urinary platinum excretion. RESULTS: Both groups of workers experienced comparable geometric mean (GM) respiratory exposure to soluble platinum (Group A = 0.744 µg m-3 versus Group B = 0.711 µg m-3) (P = 0.789), but significantly lower skin exposure (average of all measured anatomical areas) was found for Group A (Group A = 0.005 µg cm-2 versus Group B = 0.033 µg cm-2) (P = 0.018). Significantly lower skin exposure was measured on the palm (P = 0.017), wrist (P = 0.017), forehead (P = 0.027) of Group A workers compared with Group B. No significant difference was found for the urinary platinum excretion of the two groups (Group A GM = 0.208 µg g-1 creatinine versus Group B GM = 0.361 µg g-1 creatinine) (P = 0.273). CONCLUSIONS: The use of disposable coveralls and long-sleeved rubber gloves, along with strict usage procedures, proved effective in reducing precious metals refinery workers' skin exposure to soluble platinum.

Skin and respiratory exposure to platinum group metals at two South African precious metals refineries.

OBJECTIVE: Platinum Group Metals (PGMs) are mined and refined together and have the potential to elicit adverse respiratory and skin health effects. The aim of this study was to investigate the simultaneous skin and respiratory exposure of precious metals refinery workers to all six soluble PGMs. METHODS: The simultaneous skin and respiratory exposure to soluble PGMs of forty workers at two precious metals refineries were measured over two consecutive work shifts using Ghostwipes™ and Methods for the Determination of Hazardous Substances method 46/2. Skin exposure was measured on the palm, wrist, neck, and forehead of workers. RESULTS: The highest geometric mean (GM) skin exposure (average of palm, wrist, neck and forehead) was found for soluble Pt (0.008 µg/cm2) [95% confidence interval (CI) 0.005-0.013], followed, in order, by Rh, Ir, Pd, Ru, and Os. Significantly higher concentrations of soluble PGMs were found on the palm and wrist compared to the neck and forehead (p < 0.0001). The highest GM respiratory exposure was found for soluble Pd (0.342 µg/m3 [95% CI 0.163-0.718]) followed, in order, by Pt, Rh, Ru, Ir, and Os. Skin exposure to all soluble PGMs was positively correlated with respiratory exposure (r = 0.466-0.702). CONCLUSION: This is the first study to report skin exposure to all six soluble PGMs. Precious metals refinery workers were exposed to quantifiable concentrations of soluble PGMs via both the skin and inhalation. Exposure via both routes occurred together and control measures should be aimed at reducing both skin and respiratory exposure.

Urinary excretion of platinum (Pt) following skin and respiratory exposure to soluble Pt at South African precious metals refineries.

Adverse respiratory and skin health effects have been associated with occupational exposure to soluble platinum (Pt). However, the relationship between skin exposure and urinary Pt excretion has not yet been investigated. In this study we examined the relationship between skin and respiratory exposure to soluble Pt and urinary Pt excretion at two South African precious metals refineries. The skin and respiratory exposure to soluble Pt as well as the urinary Pt excretion of forty precious metals refinery workers was assessed simultaneously using Ghostwipes™, Methods for the Determination of Hazardous Substances method 46/2 and spot urine tests, respectively. The geometric mean for skin exposure to soluble Pt on four anatomical positions (palm, wrist, neck and forehead) was 0.008 µg/cm2 [95% confidence interval (CI): 0.005-0.013 µg/cm2], while the geometric mean for respiratory exposure was 0.301 µg/m3 (95%CI: 0.151-0.601 µg/m3) and the geometric mean for urinary Pt excretion was 0.212 µg/g creatinine (95%CI: 0.169-0.265 µg/g creatinine). Partial correlations identified significant positive correlations between skin exposure, respiratory exposure and urinary Pt excretion (r = 0.580 to 0.754). Skin and respiratory exposures to soluble Pt were both positively correlated with urinary Pt excretion, and both exposure routes should be considered when investigating occupational exposure to soluble Pt.

Urinary excretion of platinum from South African precious metals refinery workers.

BACKGROUND: Urinary platinum (Pt) excretion is a reliable biomarker for occupational Pt exposure and has been previously reported for precious metals refinery workers in Europe but not for South Africa, the world's largest producer of Pt. OBJECTIVE: This study aimed to quantify the urinary Pt excretion of South African precious metals refinery workers. METHODS: Spot urine samples were collected from 40 workers (directly and indirectly exposed to Pt) at two South African precious metals refineries on three consecutive mornings prior to their shifts. Urine samples were analysed for Pt using inductively coupled plasma-mass spectrometry and were corrected for creatinine content. RESULTS: The urinary Pt excretion of workers did not differ significantly between sampling days. Urinary Pt excretions ranged from <0.1 to 3.0 µg Pt/g creatinine with a geometric mean of 0.21 µg Pt/g creatinine (95% CI 0.17 to 0.26 µg Pt/g creatinine). The work area (P=0.0006; η2=0.567) and the number of years workers were employed at the refineries (P=0.003; η2=0.261) influenced their urinary Pt excretion according to effect size analyses. Directly exposed workers had significantly higher urinary Pt excretion compared with indirectly exposed workers (P=0.007). CONCLUSION: The urinary Pt excretion of South African precious metals refinery workers reported in this study is comparable with that of seven other studies conducted in precious metals refineries and automotive catalyst plants in Europe. The Pt body burden of workers is predominantly determined by their work area, years of employment in the refineries and whether they are directly or indirectly exposed to Pt.

Occupational Respiratory Exposure to Platinum Group Metals: A Review and Recommendations.

Platinum group metals (PGMs) is a group of metals that include platinum, palladium, rhodium, ruthenium, iridium, and osmium. Occupational respiratory exposure to platinum has been reported since 1945, but studies investigating occupational exposure to palladium, rhodium, ruthenium, iridium, and osmium are scarce. This review provides a summation of the information available on the respiratory exposure to PGMs in various industrial settings, methods used to assess exposure, and the possible adverse health effects resulting from occupational exposure to PGMs. Of these effects, respiratory sensitization caused by soluble PGMs is of most importance. Metallic PGMs have not been shown to cause allergic reactions. This review reiterates that occupational respiratory exposure to PGMs is dependent on the type of industry where exposure takes place, the chemical form (soluble or insoluble) of the PGMs present in the workplace air, and the tasks performed by workers in the specific work areas. Sensitization to soluble platinum is associated with the degree of exposure to soluble platinum compounds, and the highest concentrations of soluble PGMs in workplace air have been reported for precious metals refineries where personal exposures frequently exceed the occupational exposure limit for soluble platinum (2 µg/m3). Additionally, this review emphasizes that personal exposure monitoring is preferred over area monitoring when assessing workers' exposure to PGMs. The legislation applicable to occupational exposure to PGMs is also discussed, and it is highlighted that the occupational exposure limit for soluble platinum has remained unchanged, in most countries, since 1970 and that too few countries have classified PGM compounds as respiratory or skin sensitizers. Finally, recommendations are made to ensure that future investigations are comparable in terms of the type of exposure monitoring (personal or area) conducted, the type of tasks included in the exposure monitoring program, and the format in which results are reported.

In Vitro Permeation of Metals through Human Skin: A Review and Recommendations.

During the last few decades, the interest in skin permeation of, specifically, metals has increased with the in vitro method utilizing diffusion cells as the prominent method of investigating permeability. This review provides a systematic synopsis focused on an in vitro diffusion cell method utilizing human skin and examines the differences in experimental design as this could influence the results obtained. The permeation of metals such as chromium, cobalt, copper, gold, lead, mercury, nickel, palladium, platinum, rhodium, silver, titanium, and zinc are discussed. The metals included in this review, except for titanium and zinc, can permeate through intact human skin under physiological conditions. On the basis of flux values, the order of permeability could be summarized as Cu > Pb > Cr > Ni > Co > Pt > Hg > Rh (excluding nanoparticles). Permeability of metals through human skin is highly variable with the different methodologies as a contributing factor. Furthermore, metals are retained in the skin which could lead to reservoir (depot) formation and extended exposure even after the removal thereof from the outer surface of the skin. Finally, recommendations are provided on the standardization of experimental design and format of data reporting to enable the comparison of results from future in vitro metal permeation studies.

Assessment of dermal exposure and skin condition of workers exposed to nickel at a South African base metal refinery.

OBJECTIVES: The objectives of this study were to assess dermal exposure of cell workers to nickel at a South African base metal refinery and to characterize their skin condition by measuring the skin hydration and trans epidermal water loss (TEWL) indices. METHODS: The skin hydration index of the index finger, palm, neck, and forehead was measured before, during and at the end of the shift. The TEWL index was measured before and at the end of the shift. Dermal exposure samples were collected with Ghostwipes from the index finger and palm of the dominant hand, before, during, and at the end of the shift. Neck and forehead samples were collected before and at the end of the shift. Wipe samples of various surfaces in the workplace were also collected. Wipes were analyzed for nickel according to NIOSH method 9102, using inductively coupled plasma-atomic emission spectrometry. RESULTS: Hydration indices measured on the hands decreased significantly during the shift, but recovered to normal levels by the end of the shift. TEWL indices for the index finger and palm of the hands are indicative of a low barrier function even before commencement of the shift, which further deteriorated significantly during the shift. During the shift, substantial nickel skin loading occurred on the index finger and palm of the hand. Levels on the neck and forehead were much lower. Various workplace surfaces, which workers come into contact with, were also contaminated with nickel. CONCLUSIONS: The skin condition and high levels of nickel on the skin were most probably caused by inadequate chemical protection provided by protective gloves. Although, the permeability of nickel through intact skin is considered to be low, a decreased barrier function of dehydrated or slightly damaged skin will increase its permeability for nickel. The ethnicity of these exposed workers may contribute significantly toward the low incidence of allergic contact dermatitis observed. Several measures to lower dermal exposure to nickel are also recommended.