Sorption Behavior, Speciation, and Toxicity of Microplastic-Bound Chromium in Multisolute Systems

Abstract

The unexpectedly high affinity of microplastics (MPs) for heavy metals has attracted increasing attention in recent years. However, there is a scarcity of information on the effects of coexisting constituents on plastic–metal interactions, especially in terms of metal speciation. This study aimed to explore the role of benzophenone-type UV filters on the sorption, oxidation state, and toxicity of chromium (Cr) by pristine and UV-irradiated polystyrene MPs (PSMPs). Results showed that Cr uptake by PSMPs was remarkably higher when UV filters were present. This enhanced affinity was attributed to the formation of Cr–UV filter complexes together with multilayer sorption on PSMPs’ surfaces. Subsequent chemical state measurements indicated alteration of the oxidation state of MP-bound metals as a higher Cr­(VI) abundance was identified on the PSMPs with coexisting UV filters. More importantly, our toxicity assessments found that PSMP-bound Cr with a higher oxidation state displayed more severely inhibited microalgae growth. It is noteworthy that toxicological effects of Cr–UV filter complexes were observed only with PSMPs, which thus reaffirms the unique role of MPs in accumulating and transforming contaminants in natural environments. Overall, this study provides the first evidence into the effects of coexisting constituents on the oxidation states and toxicities of MP-bound heavy metals.

Bridging the Gaps between Microplastics and Human Health

“…Previous research has shown that heavy metals can easily attach to MPs, a combination that can potentially harm aquatic life and, eventually, human health by contaminating the food web [126][127][128][129][130][131]. Recent studies further indicated that UV filters used, for example, in sunscreens, can increase the toxicity of chromium metal by altering the oxidation state of MP-bound metals [132]. Generally, MPs and NPs can contain numerous toxic chemicals, as recently reviewed by the United Nations Environment Programme (UNEP) [133] and by others (e.g., [81,134]).…”

Interaction of Microbes with Microplastics and Nanoplastics in the Agroecosystems—Impact on Antimicrobial Resistance

“…Though MPs are classified as emerging pollutants, they may not be hazardous per se to living beings in their native chemical compositions in a pristine microenvironment. However, their omnipresence in the environment is a matter of concern owing to their role as a vector for several hazardous agents, including heavy metals [ 63 ], rare earth elements [ 64 ], pharmaceuticals (antibiotics) [ 65 , 66 ], personal care products [ 67 , 68 ], and a variety of other emerging contaminants of concern including microbes (antibiotic-resistant bacteria, viruses, etc.) [ 69 ].…”

Insights into the Adsorption of Copper/Zinc Ions over Aged Polyethylene and Polyethylene Terephthalate Microplastics

“…The surface charges of MPs play a defining role in their interaction with heavy metals 20,[22][23] . The zeta potential (ζ) of both pristine and aged microplastics were measured in different types of background electrolytes (i.e., NaCl, CuCl2, ZnCl2) and the results are shown in Fig.…”

“…Microplastics have been detected in various poultry and livestock meats 12,14 , raising biotoxicity concerns beyond microplastics themselves. The binding between MPs and heavy metals under a wide range of environmentally relevant conditions has been extensively explored so far [15][16][17][18][19][20][21][22][23] . Apart from many environmental factors (e.g., pH, natural organic matter (NOM), and salinity), the inherent properties of MPs, such as small size, hydrophobicity, high surface area, and abundant surface functional groups, are believed to facilitate the adsorption of heavy metals on MPs [15][16]22 .…”