Occurrence of emerging and persistent organic pollutants in dumpsite environments: A review

With the increasing global population and demand for food, many low-income earners turn to dumpsite farming: the practice of cultivating edible crops on or near waste dumpsite boundaries, as a source of food and livelihood. However, it is well-known that dumpsites contain mixed waste streams from diverse sources including households, electronics, industry, medical supplies, and beauty centres. The breakdown of such wastes generates pollutants such as industrial chemicals (microplastics, phthalate esters, polycyclic aromatic hydrocarbons, polychlorinated biphenyl, perfluorinated compounds, phenols), pharmaceuticals, and personal care products into the environment and eventually to the food chain. Many of these compounds are toxic, known endocrine disruptors and carcinogens, and can bioaccumulate in the food chain, posing ecological and human health risks. While these chemicals have been extensively studied across various environmental compartments, very few studies exist in the context of dumpsites, as food production areas. To address this knowledge gap, we conducted an in-depth literature review that selected 86 articles, published between 2000 and 2023, to explore the occurrence (presence and concentrations) of key emerging and persistent organic pollutants in dumpsite leachate, soils, and plants, at the global scale. Overall, our findings reveal a lack of standardization in waste management terminologies, with frequent confusion and interchangeable use of the terms: “dumpsites” and “landfills”. Furthermore among the relevant dumpsite studies, we found that most publications reported on microplastics (28), polyaromatic hydrocarbons (26), phthalate esters (23), polychlorinated biphenyls (21), and phenols (20). These studies also highlight significant variations in concentrations of pollutants and their measurement units, particularly for microplastics. Leachate (47) and soils (45) were the most studied matrices, while only five articles focussed on crops growing on dumpsites, limiting the overall global understanding of the dumpsite-food chain issue. Additionally, there was an imbalance in the geographical distribution of studies, with many of them conducted in Asia (49%), and Europe (30%), while fewer publications were cited from Africa (13%), North and South America (6%), and Australia (2%). Overall, our review addresses a broad spectrum of emerging pollutants, thus allowing a comprehensive evaluation of the range of chemical types and their respective concentrations in dumpsite ecosystems. Furthermore, this systematic and critical analysis helps to identify knowledge gaps related to the standardization of assessment and quantification protocols, pollutant pathways, fate and accumulation into environmental pools, as well as the potential resultant risks to the environment and human health. Such information is crucial in informing regulatory bodies and policymakers of the pollutant occurrence, guiding future research, and formulating effective regulations and remediation strategies.