Human awareness on the challenges posed by modern society to the environment is on the rise. Increasing recognition that coastal ecosystems play an essential role in providing humans with goods and services vital for their survival and well-being has led to substantial concern on the impacts posed by anthropogenic pressure. Widespread use and abuse of psychoactive drugs represent a significant environmental concern, as their continuous release to aquatic media poses a threat to the coastal environment, and ultimately to humans depending on their resources. Despite their prevalence, the impact of psychoactive drugs such as hallucinogens, opioids, among others, on marine systems remains poorly understood and has never been studied under ecologically relevant scenarios such as light pollution, which is a pervasive threat to coastal urban ecosystems. Monitoring the levels of psychoactive drugs present in the environment is essential, but it is equally important to assess whether these levels have a significant impact to humans and the environment. The complex interplay between these drugs and Artificial Light at Night (ALAN) can further exacerbate the challenges faced by marine systems. Concerns on ALAN are linked to its potential to interfere with the circadian rhythms, which regulate various physiological processes, affecting the ecology of marine organisms, and disrupting community interactions such as predation and competition. This is especially relevant in the context of exposure to psychoactive drugs as some these substances have the potential to disrupt biological processes. Thus, psychoactive drugs are expected to interact with ALAN posing ecological consequences, particularly in urban coastal areas were both are pervasive. CHILL will bridge these gaps by evaluating the occurrence and distribution of psychoactive drugs, and their eco(toxico)logical effects while addressing the environmentally relevant scenario of light pollution.
