Do Plastic Packages Provide Sufficient Photoprotection for Moisturizing Creams? ^†

Background: The effect of creams depends on their appropriate quality and stability, ensuring safe use. Since active cosmetic substances are often characterized by low stability, solar radiation has a particular impact on the durability of creams, and hence the photoprotective properties of their packaging are extremely important. Thus, to limit the negative impact of the microclimate on cosmetics, manufacturers should select packaging that ensures protection against radiation, moisture, and air movements. The study aimed to evaluate the photoprotective properties of selected plastic packaging for moisturizing creams using the hemispheric directional reflectance method.

Methods: The measurements of total hemispherical directional reflectance (THR) were performed with a 410-Solar Reflectometer (USA). This apparatus is equipped by the manufacturer with the ability to measure reflectance within seven spectral ranges from 335 nm to 2500 nm (i.e., 335–380 nm, 400–540 nm, 480–600 nm, 590–720 nm, 700–1100 nm, 1000–1700 nm, and 1700–2500 nm). Thus, the beam of radiation emitted by the reflectometer includes the ranges of UVA, visible, and infrared light. In the study, 24 plastic packages, divided into two categories depending on the color of the plastic material, i.e., white and blue plastic, were tested.

Results: The blue plastic showed a greater mean THR value than the white plastic in the 335–380 nm range only (0.216 vs. 0.090, respectively, p < 0.001). In turn, significantly higher THR was shown for the white plastic than for the blue ones in the remaining wavelength ranges, i.e., 400–540 nm (0.809 vs. 0.577, respectively), 480–600 nm (0.827 vs. 0.383, respectively), 590–720 nm (0.812 vs. 0.325, respectively), 700–1100 nm (0.744 vs. 0.530, respectively), 1000–1700 nm (0.559 vs. 0.352, respectively), and 1700–2500 nm (0.181 vs. 0.115, respectively) (p < 0.001 each).

Conclusions: The best protection against visible and infrared radiation is provided by white plastic packages, while blue plastic packages showed better protection against UVA radiation.