A Human Health Risk Assessment of Pharmaceuticals in the Aquatic Environment

Abstract

Analyses were conducted on four pharmaceutical compounds, representing different therapeutic classes, to evaluate the presence and potential adverse human health effects of trace levels of these substances in aqueous environmental media. Acetylsalicylic acid, clofibrate, cyclophosphamide, and indomethacin have been detected in aqueous environmental media including sewage treatment plant effluent, surface water, drinking water, and groundwater. An extensive literature search and chemical-specific risk assessments were performed to assess the potential human health significance of each compound's individual presence in environmental media. Safe water quality limits were estimated for each pharmaceutical by following the USEPA Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health and were compared to the concentrations found in the environment. The calculation of the provisional ambient water quality criteria involved estimation of human exposure to contaminated water, including intake via bioaccumulation in fish, and calculation of cancer risk and non-cancer hazard indices. Parameters detailing the toxicological and pharmacological nature, exposure assessment, and environmental fate and transport of each pharmaceutical were also considered. The overall conclusion was that based on available data, no appreciable risk to humans exists, as the detected concentrations of each of these pharmaceutical compounds found in aqueous media were far below the derived safe limits.

Urban farming as a possible source of trace metals in human diets

“…The process is dependent on water demand by the leaves in the aerial part of the plant. 49 Uptake of trace metals by higher or vascular plants is often through the root system, but can also occur through the leaves. It may therefore be difficult to distinguish whether the metals found in the plant tissues were originally from the air or soil.…”

“…The membrane structure of the plant root is lipophilic, which requires that the transport be facilitated by proteins with transport functions. 49,50 In the rhizosphere, metal transport is carried out by two processes known as bulk flow and diffusion. 51,52 This process of uptake by plants is soon followed by a process controlled by root pressure and leaf evaporation, called transpiration.…”

“…In a situation where the level of trace metals in soil is very high, the release of root exudates and acidification are common mechanisms that are used by plants to modify the root area to acquire nutrients from the soil. 41,49 In the case of nutrient movement across the biological membrane, plants have developed a specific mechanism meditated by proteins, for uptake, translocation and storage of the nutrients. 42,49 Membrane transporters are equipped with a structure that binds ions before transportation.…”

“…67 During exposure to high levels of trace metals, accumulated metal ions are detoxified by phytochelatins that are produced from glutathione in the plant. These metal ions are then bound to phytochelatins to form complex structures that are sequestered or compartmentalised in the vacuole., 49,67 Exposure to trace elements such as mercury, cadmium, lead and nickel in the soil, encourages the plants to formulate steps to counteract the effects of these toxins. Defensive mechanisms largely prevent the metals from getting inside the cells, but for metals that find a way into plants cells, they are neutralised and sequestered.…”

“…, 49,67 Exposure to trace elements such as mercury, cadmium, lead and nickel in the soil, encourages the plants to formulate steps to counteract the effects of these toxins. Defensive mechanisms largely prevent the metals from getting inside the cells, but for metals that find a way into plants cells, they are neutralised and sequestered.…”