RIFM fragrance ingredient safety assessment, benzaldehyde, CAS Registry Number 100-52-7

Results of patch testing with five fragrance materials hitherto not tested: A dose-finding study in the clinical population

BACKGROUND

Quantitative risk assessment (QRA) for skin sensitization is used to derive safe use levels of sensitising fragrance ingredients in products. Post-marketing surveillance of the prevalence of contact allergy to these ingredients provides relevant data to help evaluate the performance of these measures.

OBJECTIVES

To determine a suitable patch test concentration for five fragrance materials that had hitherto not been tested on a regular basis. These concentrations are then to be used in a surveillance study with patch testing consecutive patients over an extended monitoring period.

MATERIALS AND METHODS

Furaneol, CAS.3658-77-3; trans-2-hexenal, CAS.6728-26-3; 4,8-dimethyl-4,9-decadienal, CAS.71077-31-1; longifolene, CAS.475-20-7; benzaldehyde, CAS.10052-7, were patch tested with other fragrance allergens in four clinics. Patch testing was conducted in three rounds, starting with the lowest concentrations of the five ingredients. The doses were increased in the subsequent rounds if no late-appearing positive reactions and virtually no irritant reactions were reported.

RESULTS

Overall, 373 patients were tested. No positive allergic reaction was reported to the five ingredients. Patch test results of other fragrance allergens are reported.

CONCLUSIONS

The highest test concentrations are each considered safe for patch testing consecutive patients. Further surveillance based on these preparations will evaluate the hypothesis that QRA-driven consumer product levels of these fragrances can prevent sensitization.

Design, Synthesis, and Acid-Responsive Disassembly of Shell-Sheddable Block Copolymer Labeled with Benzaldehyde Acetal Junction

Smart nanoassemblies degradable through the cleavage of acid-labile linkages have attracted significant attention because of their biological relevance found in tumor tissues. Despite their high potential to achieve controlled/enhanced drug release, a systematic understanding of structural factors that affect their pH sensitivity remains challenging, particulary in the consruction of effective acid-degradable shell-sheddable nanoassemblies. Herein, the authors report the synthesis and acid-responsive degradation through acid-catalyzed hydrolysis of three acetal and ketal diols and identify benzaldehyde acetal (BzAA) exhibiting optimal hydrolysis profiles in targeted pH ranges to be a suitable candidate for junction acid-labile linkage. The authors explore the synthesis and aqueous micellization of well-defined poly(ethylene glycol)-based block copolymer bearing BzAA linkage covalently attached to a polymethacrylate block for the formation of colloidally-stable nanoassemblies with BzAA groups at core/corona interfaces. Promisingly, the investigation on acid-catalyzed hydrolysis and disassembly shows that the formed nanoassemblies meet the criteria for acid-degradable shell-sheddable nanoassemblies: slow degradation at tumoral pH = 6.5 and rapid disassembly at endo/lysosomal pH = 5.0, while colloidal stability at physiological pH = 7.4. This work guides the design principle of acid-degradable shell-sheddable nanoassemblies bearing BzAA at interfaces, thus offering the promise to address the PEG dilemma and improve endocytosis in tumor-targeting drug delivery.