Mineral Nanoparticles in Waste: Potential Sources, Occurrence in Some Engineered Nanomaterials Leachates, Municipal Sewage Sludges and Municipal Landfill Sludges

Abstract

Environmental assessment of engineered nanoparticles (ENPs) currently suffers from lack of data on production, emission, behaviour and fate in natural compartments. This paper aims to bring factual data on production amounts of ENPs and emission of mineral elements in a colloidal or nanoparticulate forms stemming from products, (e.g. cosmetics, paints, concretes) and from two potential waste sinks, namely municipal sewage sludge and nonhazardous waste landfill sludge. Based on the declaration of production and importation of ENPs in France in 2014, we set out a classification of ENPs substances comprising carbon black, organic pigments, miscellaneous organic substances and mineral ENPs. These mineral ENPs were sub-classified on the basis of production and CLP ecotoxicological and hazard classifications. Major elements (Group #1) encompass ENPs substances ubiquitous in total contents, and also as a colloid fraction in waste leachates (Si, Ca, Ti, Al, Mg, Fe, Mn, P). Minor elements were divided as ENPs with soluble substances and dissolved metal ions non-classified as ecotoxic (Group #2: Ba, Bi, Cr (III), Sr, Zr, La, Pd, Mo, W, Y, Au) or with soluble substances classified as ecotoxic and hazard statement code in the CLP regulation (Group #3: Ce, Cu, Zn, Ni, Sb, Ag, Co). Paints, concrete and particularly cosmetics proved to be sources of ENPs. Colloidal forms of elements or ENPs were found in leachate obtained from paint (Si), in cosmetics leachates (Al, Si, Ti and Zn), and in one demolition concrete (Ti). No nanoparticulate forms or fraction of Ag, Ce, Ti and Zn were identified by TEM/EDS in municipal sewage sludge. However, sewage sludge could be a sink for Group #3 elements such as Ag and Ce, since their total concentrations were significant. Based on landfill leachates from municipal solid wastes, the colloidal fraction frequently contained elements of Group #3 (Ni, Zn, Cu, Co and Sb) but with low mean concentration and more rarely Ag and Ce, indicating that the fluxes of these elements from the landfill cells should be low, except for Ce. Landfills seem to not emit ENPs in their leachates. From a regulative aspect, monitoring of Ag in sewage sludge for agricultural use could be of concern.

Assessing Sunscreen Lifecycle to Minimize Environmental Risk Posed by Nanoparticulate UV-Filters – A Review for Safer-by-Design Products

“…Its origin could be anthropogenic, in relation with white paints, toothpastes, food additives, sunscreens and façade run-offs, or pedogenic. Both origins could not be discriminated, as well as the nano or non-nano forms (Hennebert et al, 2017). Distinguishing the different origins of TiO 2 in such complex matrix indeed remains an analytical challenge.…”

“…A colloidal Ti content of 32 µg/L was detected in 2012 in a landfill leachate (Hennebert et al, 2013). In landfill leachate sludge, the total Ti concentration ranges from <5 to 35 mg/kg with a mean concentration of 23 mg/kg (n = 10) (Hennebert et al, 2017). This is up to 200 times less than representative concentration in soil, 4000 mg/kg (Lindsay, 1979) or 2400 mg/kg (Sposito, 2008), which suggests that the landfill probably acts as an ENM sink.…”

“…It was analyzed in 13 sludge samples from different regions of France. and was found to be present in half of the sludges studied (7 out of 13 raw sludges and 4 out of 9 digested sludges), revealing an order of magnitude of 50-400 mg/kg with a mean concentration of 170 mg/kg (Hennebert et al, 2017). The Ti speciation was investigated using electron microscope coupled to EDX.…”

The inherent variability of some environmental analytical methods hampers the circular economy of materials

“…The Part 5 of the Supplementary Information presents an illustrated review of 6 publications among many establishing that evidence. For instance, colloids or nanoparticles were found in all the 134 tested leachates (Hennebert et al 2014(Hennebert et al , 2017.…”