What is of least concern when dumping human wastewater into a river?

Pharmaceuticals are considered of least concern when dumping human wastewater into a river primarily due to their dilution in the larger body of water and the fact that current wastewater treatment processes can reduce their concentrations significantly. While the presence of pharmaceuticals in waterways can lead to ecological concerns, such as effects on aquatic organisms, they are often found at lower concentrations compared to other pollutants like heavy metals or pathogens that have immediate and damaging impacts on public health and ecosystems.

On the other hand, pathogens in wastewater pose a direct threat to human health and aquatic life, as they can lead to disease outbreaks. Nutrients, such as nitrogen and phosphorus, when present in excess due to wastewater discharge, can lead to eutrophication, causing harmful algal blooms and oxygen depletion in aquatic systems. Heavy metals, which can accumulate in the food chain and cause long-term ecological and health issues, are also a significant concern due to their toxicity even at low concentrations.

Given these considerations, pharmaceuticals, while not without risk, are generally managed and monitored more effectively than the other contaminants listed. This does not mean they are harmless, but in the context of immediate and severe environmental and health impacts, they are of least concern compared to pathogens, nutrients, and heavy metals in the context of human wastewater