Is E-speed dental film more sensitive to storage than D-speed dental film?

Two types of films with different speed, D-speed (Kodak Ultraspeed) and E-speed (Kodak Ektaspeed), were compared regarding film fogging under different storage conditions. The films were stored during one year at room temperature (+21 degrees C) without shielding, with 3 mm lead or with 200 mm iron shielding and in a refrigerator (+8 degrees C) without shielding. The films were processed in a standardised way and the film fog measured densitometrically each month. The film fog increased insignificantly with time for both film types under all storage conditions except in the refrigerator, where it reached unacceptably high levels and the faster film type (Kodak Ektaspeed) became unusable after 4 months storage in the refrigerator.