Occupational exposure to organotin substances: Development of a liquid chromatographic separation method for 11 organotin compounds in workplace air samples via HPLC-ICP-MS.

Organotin compounds (OTCs) are widely regulated but rank among the most used organometallic compounds in various industrial sectors. They are significantly more toxic than inorganic tin compounds. At workplaces, OTCs can be released as vapors or dust particles and can be absorbed by inhalation or skin contact. Occupational exposure thus represents a great risk for the absorption of OTCs for employees. Methods for OTCs speciation in workplace air monitoring currently do not exist. This study describes the development of a separation method for eleven in Germany regulated OTCs via HPLC-ICP-MS. The method allows a near baseline separation of MMT, MBT, MOT, MPhT, DMT, DBT, DPhT, TMT, TBT, TPhT and TTMT within 22 min on a C18 column and a ternary solvent and flow rate gradient using methanol, acetonitrile, and ultrapure water + 6% (v/v) acetic acid + 0.17% (m/v) α-tropolone. Ten analytes show linearity in the working range of 10 - 100 µg OTCs/L with R² > 0.999. Due to its high volatility the analyte TTMT showed a quadratic relationship between concentration and signal intensity with R² = 0.9998. The determination of the instrumental limits resulted in detection limits between 0.14 and 0.57 µg Sn/L and limits of quantification between 0.49 and 1.97 µg Sn/L. Over the course of this study thermal instability and cross reactivity of OTC in solution became apparent. Formation of two reaction products in mixed OTCs solutions have been observed. These effects will further be examined within development of appropriate sampling and sample preparation for workplace air to provide a suitable method for the determination of OTCs at workplaces according to normative references.

Biomonitoring of polycyclic aromatic hydrocarbons in firefighters at fire training facilities and in employees at respiratory protection and hose workshops.

Introduction: Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic to humans and are formed by incomplete combustion. PAHs are always present during firefighting operations, and fire department members can be exposed to them in the workplace. Methods: In this study, we analyzed 1-hydroxypyrene (1-OHP) in 36 urine samples from nine firefighters, collected before and after fire training sessions, and 32 urine samples from eight employees at respiratory protection and hose workshops. To assess breakthrough PAH exposure through personal protective equipment and potential dermal uptake, some of the workshop employees wore cotton garments under their regular workwear. Cotton samples were then examined for the presence of 17 semi-volatile and low-volatility PAHs. Results: After firefighting exercises, we observed approximately a fivefold increase in mean 1-OHP concentrations in samples from firefighters, from 0.24 µg/L to 1.17 µg/L (maximum: 5.31 µg/L). In contrast, 1-OHP levels in workshop employees were found to be low, with the majority of urine samples yielding concentrations below the limit of quantification (LOQ: 0.05 µg/L, maximum: 0.11 µg/L). Similarly, low PAH levels were found on the workshop employees' cotton undergarments, with maximum concentrations of 250 and 205 ng/g for pyrene and benzo[a]pyrene, respectively. Discussion: In conclusion, significant increases in 1-OHP in urine were observed in firefighters after training sessions, whereas work-related exposure remained low among workshop employees.

Estimating cobalt exposure in respirable dust from cobalt in inhalable dust.

Cobalt is a commonly used element in metal industry. Exposure to workers occurs mainly by inhalation of cobalt-containing dust. For the evaluation of cobalt exposure, risk assessment and investigations on occupational diseases, measurements of cobalt in respirable dust are needed. Up to now, often only data for cobalt in inhalable dust are available, which is due to the earlier classification of the limit value in this fraction. Therefore, a possibility to convert cobalt concentrations mathematically from inhalable into respirable concentrations is desirable. In this study, 639 parallel measurements of cobalt concentrations in inhalable (cI(Co)) and respirable dust fractions (cR(Co)) were extracted from the non-public exposure database MEGA (Measurement data relating to workplace exposure to hazardous substances, maintained at the Institute for Occupational Safety and Health of the German Social Accident Insurance) and investigated by regression analysis. For the whole dataset regression shows high quality measures (correlation coefficient R = 0.888, adjusted coefficient of determination adj. R2 = 0.788 - R2 is adjusted to sample size). Further description of the data is achieved by splitting the dataset according to the type of sampling ('stationary' and 'personal') and three working activity groups, 'high temperature processing', 'filling/transport/storage', and 'machining/abrasive techniques' (0.845 ≤ R ≤ 0.876; 0.711 ≤ adj. R2 ≤ 0.762). As subgroups of 'high temperature processing' and 'machining/abrasive techniques' two further groups could be determined. These groups are called heuristic groups, since they have to be formed non-systematically by trial and error. These heuristic groups are 'welding' and 'grinding'. They are more selective on the included working activities with adj. R2 of 0.703 and 0.748 respectively. The resulting conversion functions of all groups are power functions with exponents between 0.704 and 0.794. For the estimation of cobalt in respirable dust in other studies, it is possible to use the conversion functions of the heuristic and working activity groups. Limitations of the possibility to use the conversion functions are discussed.

Estimating nickel exposure in respirable dust from nickel in inhalable dust.

The conversion of dust components is of high importance for retrospective evaluations of exposure levels, of occupational diseases or the time trend of occupational dust exposure. For this purpose, possibilities to convert nickel concentrations from inhalable to respirable dust are discussed in this study. Therefore, 551 parallel measurements of nickel concentrations in inhalable and respirable dust fractions were extracted from the exposure database MEGA (maintained at the Institute for Occupational Safety and Health of the German Social Accident Insurance) and investigated by linear regression analysis of ln-transformed concentrations. Inhalable dust is the most important predictor variable, showing an adjusted coefficient of determination (adj. R2) of 0.767 (R2 adjusted to sample size). Since multilinear regression analysis, cannot be applied, further description of data is gained by splitting the whole dataset into working activity groups (e. g. 'high temperature processing', adj. R2 = 0.628,' filling/transport/storage' adj. R2 = 0.741, 'machining/abrasive techniques', adj. R2 = 0.777). From these groups, four task restrictive subgroups, so-called 'heuristic groups', can be derived by pooling similar working tasks with similar regression coefficients and enhanced quality measures (adj. R2 between 0.724 and 0.924): 'welding (grinding time fraction [GTF] < 5%)', 'welding (grinding time fraction [GTF] > 5%)', 'high temperature cutting' and 'grinding'. For the working activity group 'high temperature processing' and the heuristic group 'welding' the determination of the grinding time fraction and its inclusion or exclusion from a dataset has a huge impact on the description of data and whether a transformation of nickel concentrations using the natural logarithm (ln) is necessary or not. In case of GTF < 5%, the conversions functions are linear, all other conversion functions are power functions with exponents between 0.713 and 0.986. It is possible to develop conversion functions for estimating the nickel concentration in the respirable dust fraction (cR(Ni)) out of the nickel concentration in the inhalable dust fraction (cI(Ni)). For the estimation of Nickel in respirable dust other studies, it is recommend to use the conversion functions of the heuristic trial and error groups. Limitations of the possibility to use the conversion functions are discussed.

Metal exposure of workers during recycling of electronic waste: a cross-sectional study in sheltered workshops in Germany.

OBJECTIVES: In Germany, the initial step of electronic waste (e-waste) recycling frequently takes place in sheltered workshops for physically and mentally handicapped workers (Werkstätten für behinderte Menschen (WfbM), in german language). E-waste recycling involves a potential risk of exposure to toxic metals. Therefore, we assessed the occupational exposure of recycling workers to toxic metals to identify potential health risks and insufficient protective measures. METHODS: We used a combined air- and bio-monitoring approach to determine exposure of recycling workers to toxic metals. Air and urine samples were collected in five sheltered workshops in Germany and were analysed for their content of aluminium, antimony, arsenic, beryllium, cadmium, chromium, cobalt, mercury and nickel. Results were compared to German and international occupational limit values and to metal exposures of workers in conventional e-waste recycling firms. RESULTS: Exposure of recycling workers in five German sheltered workshops to the studied metals and their compounds was below German and international occupational limit values across all facilities studied considering both air and urine samples. Workers in the present study were not exposed to higher amounts of toxic metals than workers in conventional e-waste recycling firms. CONCLUSION: This is the first study on toxic metal exposure of recycling workers in sheltered workshops. The results of this study revealed a low occupational exposure of e-waste recycling workers to toxic metals in this type of enterprises. Current work methods and safety measures provide the workers with adequate protection.

Comparison of Microwave-Assisted Digestion and Consensus Open-Vessel Digestion Procedures for Evaluation of Metalliferous Airborne Particulate Matter.

Metal occupational exposure limits mainly focus on total content of the respective metals of interest. The methods applied for trace metal analysis in occupational health and safety laboratories are usually standardized to pragmatic consensus digestion schemes, ensuring comparability of results. The objective of the present study entailed the evaluation of a recently developed HNO3-only microwave-assisted digestion procedure by comparison with the German consensus hot-block digestion and other national digestion schemes. An inter-laboratory comparison test with participation of nine national occupational health and safety laboratories from Europe and North America was organized. For adequate emulation of what workers are at risk of inhaling four different industrial metal processing workplace dusts (electronic recycling, high-speed steel grinding, cylinder head cleaning, and battery combustion ash) were homogenized and sieved to the particle size < 100 µm diameter at IFA. The participants were asked to process air sample-typical amounts according to the German hot-plate technique, the IFA microwave-assisted digestion scheme as well as their national or in-house conventional digestion method for airborne dust and analyze for Cd, Co, Cr, Co, Fe, Mg, Ni, Pb, and Zn. Recoveries (relative to consensus open-vessel digestion) obtained for the new IFA microwave-assisted digestion were between 88 and 114% and relative reproducibility standard deviations were <10% for most metals of interest. The in-house digestion procedures applied varied widely but (whether microwave, hot block, or open vessel) yielded comparable results for the predominantly elemental alloy type dusts supplied. Results become more diverse for the combustion dust, especially if a combination of microwave-assisted digestion procedures with high temperatures and hydrofluoric acid is applied. ISO 15202-2 is currently being revised; this digestion procedure will be included as a possible variant in annex 2.

Modelling of occupational exposure to inhalable nickel compounds.

The aim of this study was to estimate average occupational exposure to inhalable nickel (Ni) using the German exposure database MEGA. This database contains 8052 personal measurements of Ni collected between 1990 and 2009 in adjunct with information on the measurement and workplace conditions. The median of all Ni concentrations was 9 µg/m3 and the 95th percentile was 460 µg/m3. We predicted geometric means (GMs) for welders and other occupations centered to 1999. Exposure to Ni in welders is strongly influenced by the welding process applied and the Ni content of the used welding materials. Welding with consumable electrodes of high Ni content (>30%) was associated with 10-fold higher concentrations compared with those with a low content (<5%). The highest exposure levels (GMs ≥20 µg/m3) were observed in gas metal and shielded metal arc welders using welding materials with high Ni content, in metal sprayers, grinders and forging-press operators, and in the manufacture of batteries and accumulators. The exposure profiles are useful for exposure assessment in epidemiologic studies as well as in industrial hygiene. Therefore, we recommend to collect additional exposure-specific information in addition to the job title in community-based studies when estimating the health risks of Ni exposure.