Influence of artificial sebum on the dermal absorption of chemicals in excised human skin: A proof-of-concept study.

In an initial diffusion cell study, the influence of artificial sebum on dermal penetration and intradermal reservoir of ethanol and toluene was investigated in comparison with the effects of a skin cream (o/w- and w/o-emulsion) and untreated (control) skin. Human skin was exposed to neat ethanol and toluene for 4h, respectively. During the experiments, the penetration of the compounds was assessed in the receptor fluid.

Evaluation of the effect of skin cleaning procedures on the dermal absorption of chemicals.

To reduce the internal exposure, skin decontamination is the most important measure after dermal contact to chemicals. However, no harmonized skin cleaning procedure for experimental ex vivo studies is published. In our study, the impact of two skin cleaning techniques on dermal penetration kinetics and intradermal deposition of 1,4-dioxane, 5% hydrofluoric acid (HF, detected in terms of fluoride ions), and anisole was evaluated to develop a reliable ex vivo skin cleaning method using the diffusion cell technique.

Percutaneous absorption of aromatic amines and the risk assessment resulting from the dermal pathway.

Aromatic amines (AA) are compounds of different carcinogenic potency causing occupational bladder cancer. The percutaneous absorption of AA is mostly appraised to be high. Many AA are, therefore, assigned with skin notations.

Potential of the octanol-water partition coefficient (logP) to predict the dermal penetration behaviour of amphiphilic compounds in aqueous solutions.

Aqueous amphiphilic compounds may exhibit enhanced skin penetration compared with neat compounds. Conventional models do not predict this percutaneous penetration behaviour. We investigated the potential of the octanol-water partition coefficient (logP) to predict dermal fluxes for eight compounds applied neat and as 50% aqueous solutions in diffusion cell experiments using human skin.

Influence of dietary factors, age and nickel contact dermatitis on nickel excretion.

Background: Nickel is a frequently detected cause of allergic contact dermatitis. Ingestion of nickel may lead to flares of nickel contact dermatitis.

Methods: We examined nickel excretion in the urine of 164 female patients with and without nickel contact dermatitis.

Comparison of experimentally determined and mathematically predicted percutaneous penetration rates of chemicals.

The aim of the study was to evaluate the predictive potential of three different mathematical models for the percutaneous penetration of industrial solvents with respect to our experimental data. Percutaneous penetration rates (fluxes) from diffusion cell experiments of 11 chemicals were compared with fluxes predicted by mathematical models. The chemicals considered were three glycol ethers (2-butoxyethanol, diethylene glycol monobutyl ether and 1-ethoxy-2-propanol), three alcohols (ethanol, isopropanol and methanol), two glycols (ethylene glycol and 1,2-propanediol), one aromatic hydrocarbon (toluene) and two aromatic amines (aniline and o-toluidine).

Biological reference values for chemical compounds in the work area (BARs): an approach for evaluating biomonitoring data.

Biological monitoring is a routine method that has been applied in occupational medical practice for many years. A requirement for its application is the availability of criteria suitable for evaluating biomonitoring data. Health-based threshold values are particularly useful as a criterion, yet only for substances for which effect thresholds can reliably be determined.

External quality assessment of human biomonitoring in the range of environmental exposure levels.

The number of human biomonitoring (HBM) applications for identifying and assessing the chemical exposure of the general population from the environment has distinctly increased during the last decade. An appropriate external quality assessment of the applied methods is essential to assure the accuracy and the comparability of HBM results. The international programme of the German External Quality Assessment Scheme (G-EQUAS) provides proficiency testing for most of the HBM parameters, which are commonly used for the assessment of the human exposure to chemicals.

Dermal uptake and excretion of 4,4'-methylenedianiline during rotor blade production in helicopter industry--an intervention study.

Objectives: Workers using composite materials by fibre reinforced laminate technology are exposed to 4,4'-methylenedianiline (MDA), a liver toxicant and suspected human carcinogen, during the production of rotor blades in helicopter industry. The aim of the study presented here was to assess the internal dose of MDA and the suitability of various personal protection measures at the workplace.

Methods: Ambient monitoring and biological monitoring was carried out by analysing MDA in air and urine samples in seven workers of a highly specialized workplace (rotor blade production).

Lead--still a health threat for marksmen.

Object: Indoor shooting is a popular recreational activity all over the world. It is also a known source of exposure to lead fumes and dusts for the general, i.e.

Biological tolerance values: change in a paradigm concept from assessment of a single value to use of an average.

Since 1981 biological tolerance values for occupational exposure (BAT values) have been published in the List of MAK and BAT Values of the Deutsche Forschungsgemeinschaft (DFG). In 2007 the list includes threshold limit values for more than 90 substances. The BAT value was defined as the maximum permissible quantity of a chemical substance or its metabolites or the maximum permissible deviation from the norm of biological parameters induced by these substances.

Enhancement of percutaneous penetration of aniline and o-toluidine in vitro using skin barrier creams.

Aniline (ANI) and the human carcinogen o-toluidine (OT) are released at the workplace during the production and processing of rubber. Recently, we showed in rubber industry workers that a frequent use of skin barrier creams (SBC) increased the internal exposure of ANI and OT. In the present study, diffusion cells were used to investigate the effects of two SBC and one skin care cream (SCC) on percutaneous penetration of neat ANI and OT as well as of OT from a mixture with a workplace specific lubricant.

Discrepancies between different rat models for the assessment of percutaneous penetration of hazardous substances.

By regulatory authorities the rat is considered to be a suitable animal model to predict the percutaneous absorption of hazardous substances in humans. In our study, the percutaneous penetration of 2-butoxyethanol (BE) and toluene was compared in different rat models. Intradermal microdialysis and static diffusion cells were used in in vivo and in vitro experiments with haired Wistar and hairless Lewis rats.

Percutaneous absorption and metabolism of 2-butoxyethanol in human volunteers: a microdialysis study.

We determined percutaneous absorption kinetics of 2-butoxyethanol (BE) in volunteers using microdialysis. Four male volunteers were dermally exposed twice to 90% and 50% aqueous solutions (v/v) of BE for 4.5h.

Monitoring of chromium and nickel in biological fluids of grinders grinding stainless steel.

Objective: Stainless steel (SS) welders usually spend some of their working time grinding, to finish and smoothen the welding groove. The aim of this study was to investigate possible relations between the concentrations of nickel (Ni) and chromium (Cr) in the work atmosphere generated by grinders grinding SS, and to compare the air levels to the levels of Cr and Ni in their biological fluids. Hereby, it might be possible to identify the contribution of grinding to the levels of Cr and Ni in biological fluids in SS welders.

Aluminosis--detection of an almost forgotten disease with HRCT.

The aim of this study was to investigate whether it is possible to detect high-resolution computed tomography (HRCT) findings in aluminium powder workers, which are consistent with early stages of aluminosis.62 male workers from 8 departments of two plants producing aluminium (Al) powder were investigated using a standardized questionnaire, physical examination, lung function analysis, biological monitoring of Al in plasma and urine, chest X-ray, HRCT and immunological tests. Chronic bronchitis was observed in 15 (24.

Biological monitoring of welders exposed to aluminium.

To evaluate an adequate strategy for biological monitoring of aluminium (Al), a group of 62 Al welders (age in 1999: 23-51 years, median 35 years) was surveyed annually from 1999 to 2003 by determination of pre- and post-shift Al in urine and plasma. Biomonitoring was supplemented by personal air measurements of the total dust concentration. The welders' internal exposure was compared to the exposure of 60 non-exposed assembly workers (age in 1999: 21-51 years, median: 36 years) who were surveyed in 1999, 2001 and 2003.

Is the permeability coefficient Kp a reliable tool in percutaneous absorption studies?

In percutaneous absorption studies the potency of penetration of chemical substances is often described by the permeability coefficient Kp. The experimentally determined Kp is characterized according to Fick's first law of diffusion by the ratio of flux and the concentration of the test compound (Kp=Flux/C). This equation implies that in percutaneous absorption studies Kp is theoretically a more reliable parameter than flux taking the concentration into consideration, and should remain constant for each compound independent from the grade of dilution.

Monitoring of chromium and nickel in biological fluids of stainless steel welders using the flux-cored-wire (FCW) welding method.

Objective: This study was undertaken to investigate the exposure to chromium (Cr) and nickel (Ni) in flux-cored wire (FCW) welders welding on stainless steel (SS).

Method/design: Seven FCW welders were monitored for 3 days to 1 workweek, measuring Cr and Ni in air, blood, and urine. The welders were questioned about exposure to Cr and Ni during their whole working careers, with emphasis on the week of monitoring, about the use of personal protective equipment and their smoking habits.

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Edible snails, kept at an adaptation temperature (AT) of 20°C, and fed with lettuce, show significant increases in levels of Zn (+84%) and Pb (+91%) in the hemolymph, Zn (+25%) in foot muscle, and Fe (+85%) and Zn (+41%) in the albumin gland.At an adaptation temperature of 5°C aestivating edible snails, which have closed the aperture of their shells with a skin slime, exhibit a lower content of Fe, Zn, and Pb in the hemolymph and other organs than do hungry edible snails at AT=20°C.The use of the edible snail on cultivated land as an indicator of levels of Fe, Zn, and Pb has the important advantage of these elements are ingested with the food and are at least temporarily stored in the hemolymph and certain organs.