The main effects of adding optical brighteners to cultural paper focus on visual comfort, potential health risks, and long-term safety. Their core function is to enhance paper whiteness, but excessive or improper use may pose health risks.
The Working Mechanism and Purpose of Optical Brighteners
Optical brighteners (also known as photocopying paper, notebooks, and books) are organic compounds that absorb ultraviolet light and emit blue-violet visible light. Through a "complementary whitening" effect, they counteract the slight yellow tint of the paper, making it appear whiter and brighter. In the production of cultural paper (such as copy paper, notebooks, and books), especially when using raw materials with low whiteness such as waste pulp, manufacturers often add optical brighteners to enhance the product's visual appeal.
Potential Impacts on Vision Health
Strong glare can easily lead to visual fatigue: High-whiteness paper reflects light more strongly under fluorescent or natural light, and prolonged viewing may cause eye discomfort, dryness, and fatigue.
Blue-violet light stimulation of the retina: Fluorescent whitening agents emit blue-violet light under ultraviolet excitation, which is high-energy visible light. Long-term exposure may adversely affect retinal photoreceptors, posing a potential threat, especially to children's visual development.
National standard restrictions: To control myopia, the national standard GB 40070-2021 stipulates that the D65 brightness of primary and secondary school students' workbooks must not exceed 85.0%, and the D65 fluorescence brightness must not exceed 5.0%, aiming to control the visual risks associated with the use of fluorescent agents.
Potential risks to human health: Although there is currently no conclusive evidence that compliant amounts of fluorescent whitening agents are directly toxic to humans, the following concerns remain:
Skin contact and migration risks: If fluorescent whitening agents are "migratory," long-term hand contact with workbooks, books, etc., may lead to absorption through sweat or minor wounds. Sensitive individuals may experience allergic reactions such as skin itching and rashes. **Liver Metabolic Burden:** Studies have shown that once fluorescent agents bind to human proteins, they require enzymatic breakdown by the liver for excretion, potentially increasing the liver's burden over time.
Higher Risk from Wound Exposure: If the skin is broken, fluorescent substances are more likely to adhere and penetrate, potentially causing local irritation or inflammation.
Key Point: In products that meet national standards, fluorescent whitening agents are usually firmly bound and do not migrate, thus posing a lower risk. The real concern is excessive additives or substandard products.
