This paper presents an in-house BAuA study on the evaluation of the COSHH Essentials exposure predictive model. External validation is based on measurement data obtained in BAuA field studies performed in various industries, e.g. printing industry and textile industry. In addition, measurement data and information on industrial hygiene provided by the chemical industry within the framework of the Existing Substances Risk Assessment programme are used. Although the evaluated exposure data cover a wide variety of activities and workplace scenarios, there is still a considerable lack of appropriate exposure data, especially for the more stringent control strategies. It was found that the level of agreement between the measurements for solid substances (powders, dusts) and the predicted ranges is reasonably good. The situation is in part different for liquids. In workplaces where organic solvents are used in litre quantities, exposure levels are within the predicted ranges or are often lower. For small-scale uses of liquids (millilitre scale), e.g. in carpenters' workshops, there were indications that the exposure levels can exceed the predicted ranges. However, it must be noted that the database is rather small.

Within the framework of European risk assessment of new and existing substances, the EASE model (Estimation and Assessment of Substance Exposure) is often applied to assess inhalative exposure at workplaces. To contribute to the validation of this model, single EASE scenarios were compared with independent measurement data on inhalative exposure to vapors and dusts. For this purpose, workplace measurements obtained in the areas of production, textile printing and coating, screen printing and offset printing, the rubber industry, and the plastics processing industry as well as flame spraying were used. A good correspondence between model estimates and measurement data was found in the case of exposure to vapors for the production of chemical substances in closed systems (EASE scenario: closed system without breaching) and for procedural control works at mainly automated printing workplaces (EASE scenarios: non dispersive use, segregation, low/medium volatility). For the handling of powdery substances measurement results obtained during weighing and filling works, in part semiautomatic, were compared with the EASE estimates for the scenario: dry manipulation, with/without local exhaust ventilation. Good correspondence was estimated if approx. 1 t to 200 t powdery substances were handled per shift. For the EASE scenarios "direct handling with natural ventilation/with local exhaust ventilation," high discrepancies exist between model prediction and measurement results obtained during manual screen printing or the preparation of printing inks.

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Total reflection X-ray fluorescence (TXRF) was applied in the analysis of metallic and ceramic materials after LA. Sample material was evaporated by the focussed radiation of a pulsed Nd : YAG laser and collected directly on a quartz or Plexiglas disc commonly used as a sample carrier for TXRF. Iron-Cr and Cu-Zn binaries, a high-alloy steel sample, and a hightemperature superconducting ceramic ( YBa,Cu,O,.g) were chosen for analysis. Only microgram quantities of sample material were removed per laser shot, and only a few nanograms of sample were deposited on the sample carrier. This minute amount was sufficient for TXRF analysis. The mass of individual elements detected by TXRF was at the pglevel, so that a mass fraction in the order of 1 mg g-' could be determined. Quantification was achieved by addition of an internal standard. Accurate results were obtained after a single laser shot of the deposits of the binary samples, the steel sample and the ceramic material. Deviations from the correct composition were only observed for the Cu-Zn binaries when using multiple laser shots. The combination of LA with TXRF detection enables ultra-microanalysis of solids without laborious sample preparation steps. By repetitive laser pulses upon neighbouring spots a microdistribution analysis may become possible with a lateral resolution of about 10 pm.