A process chain to produce and characterize nanoparticulate, hydrophobic resin coatings was investigated. The investigated process stain could be used for sanitary applications, for instance. Nanocomposites might have a potential risk to humans and the environment. Thus, not only the manufacturing process, but also the achievable product properties were examined. Toxicological investigations with regard to the nanoparticle sizes and solid contents used were performed by investigating the impact of the nanoparticles on lung (A549 cells) and liver (HepG2 cells) cells. Results included showed that by using modified alumina the product properties could be improved in terms of hydrophobicity and mechanical properties and that alumina particles were nontoxic. However, cell viability was slightly affected by the nanocomposite extracts, depending on the applied particle size and concentration in the nanocomposites.