DNA damage in bone marrow and blood cells of mice exposed to municipal sludge leachates

A comprehensive overview on solid waste leachate effects on terrestrial organisms

Leachate is a highly complex waste with high toxicological potential that poses a significant threat to the terrestrial environment. Determining leachate physicochemical parameters and identifying xenobiotics alone is, however, not enough to determine the real environmental impacts. In this context, the use of terrestrial model organisms has been highlighted as a tool in ecotoxicological leachate assessments and as a guiding principle in risk assessments. In this context, this review aimed to present the most current state of knowledge concerning leachate toxicity and the bioassays employed in this evaluation concerning terrestrial plants and animals. To this end, a literature search on leachate effects on terrestrial organisms was carried out using ten search terms, in 32 different combinations, at the Web of Science and Scopus databases. A total of 74 eligible articles were selected. The retrieved studies analyzed 42 different plant and animal species and employed nine endpoints, namely phytotoxicity, genotoxicity, bioaccumulation, antioxidant system, cytotoxicity, reproduction, physiological changes, behavior and lethality. A frequent association of toxic leachate effects with metals was observed, mainly Pb, Cd, Cr, Mg, Zn and Cr, which can cause antioxidant system alterations and cyto- and genotoxicity. These elements have also been associated to reproductive effects in earthworms and mice. Specifically concerning plants, most of the retrieved studies employed Allium cepa in toxicity assays, reporting phytotoxic effects frequently associated to metals and soil parameter changes. Animal studies, on the other hand, mostly employed mice and evaluated genotoxicity and antioxidant system effects. Even with the description of toxic leachate effects in both plants and animals, a lack of knowledge is still noted concerning reproductive, physiological, cytotoxic, and behavioral effects in terrestrial species. We, thus, suggest that further studies be carried out on other animals, advancing our understanding on potential environmental leachate effects, also allowing for human health risk assessments.

Investigating landfill leachate toxicity in vitro: A review of cell models and endpoints

Landfill leachate is a complex mixture characterized by high toxicity and able to contaminate soils and waters surrounding the dumpsite, especially in developing countries where engineered landfills are still rare. Leachate pollution can severely damage natural ecosystems and harm human health. Traditionally, the hazard assessment of leachate is based on physicochemical characterization but the toxicity is not considered. In the last few decades, different bioassays have been used to assess the toxicity of this complex matrix, including human-related in vitro models. This article reviews the cell bioassays successfully used for the risk assessment of leachate and to evaluate the efficiency of toxicity removal of several processes for detoxification of this wastewater. Articles from 2003 to 2018 are covered, focusing mainly on studies that used human cell lines, highlighting the usefulness and adequacy of in vitro models for assessing the hazard involved with exposure to leachate, particularly as an integrative supporting tool for chemical-based risk assessment. Leachate is generally toxic, mutagenic, genotoxic and estrogenic in vitro, and these effects can be measured in the cells exposed to already low concentrations, confirming the serious hazard of this wastewater for human health.

Municipal leachates health risks: Chemical and cytotoxicity assessment from regulated and unregulated municipal dumpsites in Lebanon

The proper management of municipal waste is critical for resource recovery, sustainability and health. Lebanon main approach for managing its municipal waste consisted of landfill disposal with minimal recycling capacity. This approach contributed to exceeding the holding capacity of existing landfills leading eventually to their closures. The closure of a major landfill (Naameh landfill) servicing Beirut and Mount Lebanon areas led to municipal wastes piling in the streets and forests for more than a year in 2016. The main problem identified in the municipal wastes consisted of untreated leachates (from regulated and unregulated dumpsites) going straight into the Mediterranean Sea. Therefore leachate samples were collected and subjected to chemical characterization followed by biological assessment. The chemical characterization and profiling of the Lebanese leachates were compared to results reported in Lebanon, Europe and United States as well as to the toxicity reference values (TRV). The biological assessment was conducted in vitro using human derived immortalized cell cultures. This strategy revealed significant alarming cellular organelles and DNA damages using in vitro cytotoxicity assays (MTS and comet assay). The significant damages observed at the cellular level prompted further animal model investigations using BALB/c mice. The animal data pointed to significant upregulation of liver activity enzymes coupled with significant damage expression in liver spleen and bone marrow DNA. The presented research clearly indicated that there is an urgent need for development of national waste strategies for proper treatment and disposal of municipal waste leachates in Lebanon.

Chemical and toxicological characterization of the bricks produced from clay/sewage sludge mixture

The present study aimed to characterize chemical properties of clay bricks containing 20 % of sewage sludge. After detection of potentially hazardous metals, we simulated precipitation exposure of such material to determine the amount of heavy metals that could leach out of the bricks. Metals, such as copper, zinc, nickel, cobalt, chromium, etc., were detected in leachate in low concentrations. Moreover, human peripheral blood lymphocytes were exposed to brick leachate for 24 h in order to evaluate its possible negative impact on human cells and genome in vitro. Cytotoxicity tests showed no effect on human peripheral blood lymphocytes viability after exposure to brick's leachate. On the contrary, the alkaline comet assay showed slight but significant increase in DNA damage with all three parameters tested. As we might predict, interactions of several heavy metals in low concentrations could be responsible for DNA damaging effect. In that manner, our findings suggest that leachates from sewage sludge-produced bricks may lead to adverse effects on the exposed human population, and that more stabile bricks should be developed to minimize leaching of heavy metals into the environment. Bricks with lower percentage of the sludge may be one of the solutions to reduce the toxic effect of the final product.

Residential proximity to waste sites and industrial facilities and chromosomal anomalies in offspring

A few studies have found chromosomal anomalies in offspring associated with a maternal residence near waste sites, but did not examine the effect of living near industrial facilities, and most combined specific anomalies into heterogeneous groups. With a case-control study design, we investigated whether maternal residential proximity to hazardous waste sites or industrial facilities with chemical air emissions was associated with chromosomal anomalies in births. Maternal residences of 2099 Texas births with chromosomal anomalies and 4368 control births without documented malformations were related to boundaries of hazardous waste sites and street addresses of industrial facilities through geographic information systems. With adjustment for maternal age, race/ethnicity, and education, maternal residence within 1mile of a hazardous waste site (relative to farther away) was not associated with chromosomal anomalies in offspring except for Klinefelter variants among Hispanic births (odds ratios (OR) 7.9, 95% confidence interval (CI) 1.1-42.4). Women 35 years or older who lived within 1mile of industries with emissions of heavy metals were two times more likely (95% CI 1.1-4.1) than women living farther away to have offspring with chromosomal anomalies including trisomies 13, 18, or 21 or sex chromosome abnormalities. Among women 40 years or older, maternal residence within a mile of industries with solvent emissions was associated with chromosomal anomalies in births (OR 4.8, 95% CI 1.2-42.8). Study findings suggest some relation between residential proximity to industries with emissions of solvents or heavy metals and chromosomal anomalies in births to older mothers.