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2019
2019
The concept of essential use for determining when uses of PFASs can be phased out
Because of the extreme persistence of per- and polyfluoroalkyl substances (PFASs) and their associated risks, the Madrid Statement argues for stopping their use where they are deemed not essential or when safer alternatives exist. To determine when uses of PFASs have an essential function in modern society, and when they do not, is not an easy task. Here, we: (1) develop the concept of “essential use” based on an existing approach described in the Montreal Protocol, (2) apply the concept to various uses of PFASs to determine the feasibility of elimination or substitution of PFASs in each use category, and (3) outline the challenges for phasing out uses of PFASs in society. In brief, we developed three distinct categories to describe the different levels of essentiality of individual uses. A phase-out of many uses of PFASs can be implemented because they are not necessary for the betterment of society in terms of health and safety, or because functional alternatives are currently available that can be substituted into these products or applications. Some specific uses of PFASs would be considered essential because they provide for vital functions and are currently without established alternatives. However, this essentiality should not be considered as permanent; rather, constant efforts are needed to search for alternatives. We provide a description of several ongoing uses of PFASs and discuss whether these uses are essential or non-essential according to the three essentiality categories. It is not possible to describe each use case of PFASs in detail in this single article. For follow-up work, we suggest further refining the assessment of the use cases of PFASs covered here, where necessary, and expanding the application of this concept to all other uses of PFASs. The concept of essential use can also be applied in the management of other chemicals, or groups of chemicals, of concern.
2019
2019
2019
Electronic waste (e-waste) is informally processed and recycled in Agbogbloshie in Accra (Ghana), which may be the largest such site in West Africa. This industry can lead to significant environmental contamination. In this study, surface dust samples were collected at a range of sites within Accra to establish the offsite consequences of such activities. Fifty-one samples were collected and analysed for 69 elements by ICP-mass spectrometry after nitric acid digestion. The data indicated a significant enrichment in metals associated with solder and copper wire at the site itself and a downwind dispersion of this source material to a distance of approximately 2.0 km. Chlorine and bromine were also elevated at this site as residues from polyvinyl chloride combustion and flame retardants respectively. The elemental composition indicated that only low technology electrical equipment was being treated this way. Multivariate statistical analyses by principal components analysis and polytopic vector analysis identified three sources contributing to the system; (i) burn site residue dispersing within 2 km from the source site, (ii) marine matter on the beaches alone and (iii) the baseline soil conditions of the city of Accra. Risk ratios and hazard quotients developed from the measured concentrations indicated that copper was providing the greatest risk to inhabitants in most cases although nickel, vanadium, chromium and zinc also contributed.
2019
The comet assay applied to HepG2 liver spheroids
In accordance with the 3 Rs to reduce in vivo testing, more advanced in vitro models, moving from 2D monolayer to 3D cultures, should be developed for prediction of human toxicity of industrial chemicals and environmental pollutants. In this study we compared cytotoxic and genotoxic responses induced by chemicals in 2D and 3D spheroidal cultures of the human liver cancer cell line HepG2.
HepG2 spheroids were prepared by hanging drop technology. Both 3D spheroids and 2D monolayer cultures were exposed to different chemicals (colchicine, chlorpromazine hydrochloride or methyl methanesulfonate) for geno- and cytotoxicity studies. Cytotoxicity was investigated by alamarBlue assay, flow cytometry and confocal imaging. DNA damage was investigated by the comet assay with and without Fpg enzyme for detection of DNA strand breaks and oxidized or alkylated base lesions.
The results from the cyto- and genotoxicity tests showed differences in sensitivity comparing the 2D and 3D HepG2 models. This study shows that human 3D spheroidal hepatocellular cultures can be successfully applied for genotoxicity testing by the comet assay and represent a promising advanced in vitro model for toxicity testing.
2019