Bornehag et al. (2004) report statistically significant associations between BBP levels in dust and the induction of rhinitis and eczema and between DEHP levels in dust and asthma. They assert that the different associations "can be explained by a combination of chemical physical properties and toxicological potential." and that the results have "global implications." In the July 24 issue of Science News Danish Toxicologist Gunnar Damgaard Nielsen of the National Institute of Occupational Health in Copenhagen said: "whether there is a causal relationship between phthalates and promotion of asthma is not clear." In its analysis, Bornehag’s group didn’t include factors that influence the abundance of allergens, such as a home’s humidity and cleanliness. Furthermore, Nielsen notes, vinyl flooring is often used in buildings with other cheap materials, some of which may independently promote the growth of allergy-causing moulds and dust mites.