Global scanning of antihistamines in the environment: Analysis of occurrence and hazards in aquatic systems.

Concentration of the global population is increasingly occurring in megacities and other developing regions, where access to medicines is increasing more rapidly than waste management systems are implemented. Because freshwater and coastal systems are influenced by wastewater effluent discharges of differential quality, exposures in aquatic systems must be considered. Here, we performed a global scanning assessment of antihistamines (AHs), a common class of medicines, in surface waters and effluents. Antihistamines were identified, literature occurrence and ecotoxicology data on AHs collated, therapeutic hazard values (THVs) calculated, and environmental exposure distributions (EEDs) of AHs compared to ecotoxicity thresholds and drug specific THVs to estimate hazards in surface waters and effluents. Literature searches of 62 different AHs in environmental matrices identified 111 unique occurrence publications of 24 specific AHs, largely from Asia-Pacific, Europe, and North America. However, the majority of surface water (63%) and effluent (85%) observations were from Europe and North America, which highlights relatively limited information from many regions, including developing countries and rapidly urbanizing areas in Africa, Latin America and Asia. Less than 10% of all observations were for estuarine or marine systems, though the majority of human populations reside close to coastal habitats. EED 5th and 95th centiles for all AHs were 2 and 212ng/L in surface water, 5 and 1308ng/L in effluent and 6 and 4287ng/L in influent, respectively. Unfortunately, global hazards and risks of AHs to non-target species remain poorly understood. However, loratadine observations in surface waters exceeded a THV without an uncertainty factor 40% of the time, indicating future research is needed to understand aquatic toxicology, hazards and risks associated with this AH. This unique global scanning study further illustrates the utility of global assessments of pharmaceuticals and other contaminants to identify chemicals requiring toxicology study and regions where environmental monitoring, assessment and management efforts appear limited and necessary.