Organic compounds in water extracts of coal: links to Balkan endemic nephropathy

Abstract

The Pliocene lignite hypothesis is an environmental hypothesis that has been proposed to explain the etiology of Balkan endemic nephropathy (BEN). Aqueous leaching experiments were conducted on a variety of coal samples in order to simulate groundwater leaching of organic compounds, and to further test the role of the Pliocene lignite hypothesis in the etiology of BEN. Experiments were performed on lignite coal samples from endemic BEN areas in Romania and Serbia, and lignite and bituminous coals from nonendemic regions in Romania and the USA. Room temperature, hot water bath, and Soxhlet aqueous extraction experiments were conducted between 25 and 80 °C, and from 5 to 128 days in duration. A greater number of organic compounds and in higher concentrations were present in all three types of leaching experiments involving endemic area Pliocene lignite samples compared to all other coals examined. A BEN causing molecule or molecules may be among phenols, PAHs, benzenes, and/or lignin degradation compounds. The proposed transport pathway of the Pliocene lignite hypothesis for organic compound exposure from endemic area Pliocene lignite coals to well and spring drinking water, is likely. Aromatic compounds leached by groundwater from Pliocene lignite deposits in the vicinity of endemic BEN areas may play a role in the etiology of the disease. A better understanding of organic compounds leached by groundwater from Pliocene lignite deposits may potentially lead to the identification and implementation of effective strategies for the prevention of exposure to the causative agent(s) for BEN, and in turn, prevention of the disease.

Limitations and plausibility of the Pliocene lignite hypothesis in explaining the etiology of Balkan endemic nephropathy

“…30,31 (However, see the Exposure Pathway is Unlikely section for contradictory results.) Also, greater numbers and higher concentrations of organic compounds were shown to be present in endemic vs nonendemic area water 39 and methanol 30,34 extracts of lignite samples. Furthermore, human mesenchymal stem cells exposed to a water extract of an endemic area Pliocene lignite showed increased cellular proliferation and differentiation compared to the control, 37 and human kidney cells exposed to concentrated high-molecular-weight organic compounds from an endemic village water sample showed excess cell death or proliferation compared to controls.…”

“…In addition, though some limitations have been addressed in the literature, information exists only in a piecemeal manner, e.g., in studies from 1991 16 to 2013. 39 Therefore, herein presented for the first time is a comprehensive compilation of the possible limitations of the hypothesis, with each limitation addressed in turn. The objective of this study was to systematically evaluate the role of the tenets of the Pliocene lignite hypothesis in the etiology of BEN in order to provide an improved understanding of the hypothesis for colleagues, patients, and those affected by the disease.…”

“…For example, of immigrants who settled into endemic areas, only after a minimum of y20 years were they likely to develop the disease, suggesting low dose exposure to, e.g., a fixed environmental factor. Also, greater numbers and higher concentrations of organic compounds were shown to be present in endemic vs nonendemic area water samples, 30,31 and in endemic vs nonendemic area water 39 and methanol 30,34 extracts of lignite samples, showing the potential for differential exposure of the populations to the possible causative agents. However, many limitations of the hypothesis have been noted in the literature.…”

“…The Pliocene lignite hypothesis posits that BEN is caused by long-term exposure to low concentrations of toxic organic compounds leaching into drinking water, that is used almost exclusively by the population, via groundwater from Pliocene lignites found in the vicinity of endemic settlements. 16,24,27,28 Many studies have been conducted to test the role of the Pliocene lignite hypothesis in the etiology of BEN, [27][28][29][30][31][32][33][34][35][36][37][38][39] and many characteristics of the disease have been shown to be consistent with the hypothesis. For example, of immigrants who settled into endemic areas, only after a minimum of y20 years were they likely to develop the disease, suggesting low dose exposure to, e.g., a fixed environmental factor.…”

Environmentally-related health impacts of coal seam gas development: An impact assessment approach in Queensland, Australia

“…These outcomes relate to toxic organic compounds derived from coal, which can seep into water supplies, resulting in higher incidence of kidney disease in populations using untreated water as a water source (Orem, Tatu, Pavlovic, et al, 2007). Leaching tests on coal samples from Balkan Endemic Nephropathy areas found that there were more organic compounds than in other areas and the compounds existed in higher concentrations in the Balkan Endemic Nephropathy area coal samples compared to other coal samples (Maharaj, Orem, Tatu, Lerch, & Szilagyi, 2014).…”