Plasticizer adjuvant effect

Recently, the most important phthalate plasticizers have been investigated for adjuvant effect. The first investigation, indicating a possible interplay between phthalate plasticizers and airway allergy, was an epidemiological study published in 1997. This study hypothesized that the plasticizer di-(2-ethylhexyl) phthalate, DEHP, in PVC materials promoted development of asthma in children. However, it was not possible to show definitively that DEHP is an adjuvant. To elucidate whether phthalate plasticizers actually possess adjuvant effect, series of phthalates and their monophthalate metabolites were studied in an animal model. These studies " are the only controlled studies, which allow scientific insight in adjuvant effect of phthalate plasticizers and the results are summarized in the present chapter. 

Several studies indicate that the presence of errvirorrmental adjuvants such as diesel exhaust particles may play a role in the development of airway allergies. " It has recently been suggested that also phthalate plasticizers may possess adjuvant effect, which is in... 

DEPs and the polycyclic aromatic hydrocarbons adsorbed to the surface of DEPs are adjuvants. " The allergic response may be characterized by the formation of IgE antibodies, among others. These play a major role in the pathogenesis of Type I allergies such as rhinitis and asthma. Other chemicals such as detergents have been shown to possess adjuvant effect." " Recent studies have also shown that phthalate plasticizers may be adjuvants. ... 

Recently, a matched case-control study in a cohort of 3754 newborns in Oslo, Norway, showed an increased risk for bronchial obstraction in children living in apartments with high occurrence of plasticized polyvinylchloride, PVC, floorings. Many other factors such as ventilation, tobacco smoking and crowdedness (square meters per occupant) were included in the study. As the study showed a correlation between the risk of developing asthma and exposure to PVC floors, the authors suggested that the plasticizers, which mairdy consisted of di-(2-ethylhexyl) phthalate, DEHP, had adjuvant effect. ... 

So far, phthalates and their metabolites are the only plasticizer types for which studies of adjuvant activity have been pubhshed. Adjuvant effects were seen on the IgE and IgGl... 

Epidemiological studies suggest that phthalate plasticizers m possess adjirvant effect and, thus, may promote development of allergic airway diseases. Recent studies in arri-mals demonstrated that several of the commonly used phthalate plasticizers were adjuvants although their potentials as adjrrvants varied. The adjuvant effect observed in the animal studies occttrred with concentratiorrs which were at the same levels as observed for... 

As the adjuvant effect varied with the chemical stracture of the phthalates, this suggests that plasticizers with appropriate technical properties but without adjuvant effect may be developed. 

All diffusion processes involving the transfer of a diffusantfrom or to a polymeric material asymptotically reaches a steady condition at long times. In any closed system (like a Tetra Pak carton) that has reached this condition, there is no effective mass transfer between the polymer and the surrounding phases the adjuvant concentrations are at equilibrium, and the transferred material is at the maximum possible amount In reference to Fig. 11.25 b, consider a sorption or migration process that has reached equilibrium. is the volume of contacting phase, and Vp is the volume of plastic in the container, and c y and c are the equilibrium concentrations of the adjuvant in the contacting phase and polymer, respectively. For the case of sorption of a substance from the food phase by the polymer, the mass balance at equilibrium is... 

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