The aim of this work was to identify the key mechanisms governing transport of organic chemical substances from consumer articles to cotton wipes. The results were used to establish a mechanistic model to improve assessment of dermal contact exposure. Four types of PVC flooring, 10 types of textiles and one type of inkjet printed paper were used to establish the mechanisms and model. Kinetic extraction studies in methanol demonstrated existence of matrix diffusion and indicated the presence of a substance surface layer on some articles. Consequently, the proposed substance transfer model considers mechanical transport from a surface film and matrix diffusion in an article with a known initial total substance concentration. The estimated chemical substance transfer values to cotton wipes were comparable to the literature data (relative transfer ∼ 2%), whereas relative transfer efficiencies from spiked substrates were high (∼ 50%). For consumer articles, high correlation (r(2)=0.92) was observed between predicted and measured transfer efficiencies, but concentrations were overpredicted by a factor of 10. Adjusting the relative transfer from about 50% used in the model to about 2.5% removed overprediction. Further studies are required to confirm the model for generic use.
An HPLC method was developed for application in the measurement of occupational exposure to the pesticide chlorothalonil. In addition, sampling methods were validated for the determination of exposure to chlorothalonil in the greenhouse culturing of carnations. Procedures for sampling of the inspirable fraction of aerosols, for the determination of hand contamination by hand rinse and the use of cotton gloves, and for the determination of dislodgable chlorothalonil residues on carnation leaves were validated. Normal phase HPLC with hexane-dioxane as the eluent and UV detection at either 254 or 325 nm appeared suitable for the determination of chlorothalonil in the described matrices. The limit of detection, after concentration on SepPak C18 cartridges was approximately 0.5 micrograms/L. Linear calibration curves were obtained in concentration ranges from 0.5 microgram/L to 100 mg/L. In general, no interferences were noticed in the analysis of the matrices. However, cotton gloves for determination of hand contamination had to be washed before use because they contained interfering material, and in the case of air sampling, glass fiber filters for air sampling appeared to degrade chlorothalonil very rapidly. Therefore, cellulose filters were used for collection of the inspirable fraction of aerosols containing chlorothalonil.
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