Abstract
Pharmaceutically active compounds (PhACs) are widely used in medical treatments but pose risks to ecosystems and human health when present in the environment. Understanding their fate in nature is complex and influenced by various factors. Phototransformation, where PhACs change chemically upon light exposure, offers the potential for reducing their environmental levels. Studying this process is crucial for understanding risks, developing safe disposal strategies, and innovating removal methods to mitigate adverse effects. This review delves into the major factors influencing the transformation of PhACs under natural conditions. It provides a comprehensive analysis of the mechanisms involved in the photochemical activity of PhACs, shedding light on their behavior upon exposure to sunlight. Special attention is given to delineating the differences in the phototransformation processes among 13 major pharmaceutical classes. By examining the various factors influencing PhAC transformation and elucidating their mechanisms, this review aims to contribute to a deeper understanding of the fate of pharmaceuticals in the environment. Such insights are invaluable for developing effective strategies to mitigate the risks posed by PhAC contamination and safeguarding environmental and human health.