Rare earth elements (REEs) are key constituents of modern technology and play important roles in various chemical and industrial applications. They also are increasingly used in agricultural and zootechnical applications, such as fertilizers and feed additives. Early applications of REEs in agriculture have originated in China over the past several decades with the objective of increasing crop productivity and improving livestock yield (e.g., egg production or piglet growth). Outside China, REE agricultural or zootechnical uses are not currently practiced. A number of peer-reviewed manuscripts have evaluated the adverse and the positive effects of some light REEs (lanthanum and cerium salts) or REE mixtures both in plant growth and in livestock yield. This information was never systematically evaluated from the growing body of scientific literature. The present review was designed to evaluate the available evidence for adverse and/or positive effects of REE exposures in plant and animal biota and the cellular/molecular evidence for the REE-associated effects. The overall information points to shifts from toxic to favorable effects in plant systems at lower REE concentrations (possibly suggesting hormesis). The available evidence for REE use as feed additives may suggest positive outcomes at certain doses but requires further investigations before extending this use for zootechnical purposes.

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Two microplastic sets, polystyrene (PS) and polymethyl methacrylate (PMMA), were tested for adverse effects on early life stages of Sphaerechinus granularis sea urchins.Microparticulate PS (10, 80 and 230 µm diameter) and PMMA (10 and 50 µm diameter) were tested on developing S. granularis embryos from 10 min post-fertilisation (p-f) to the pluteus larval stage (72 h p-f), at concentrations ranging from 0.1 to 5 mg L -1 . Both PS and PMMA exposures resulted in significant concentration-related increase of developmental defects and of microplastic uptake in plutei. Moreover, embryo exposures to PS and PMMA (5 and 50 mg L -1 ) from 10 min to 5 h p-f resulted in a significant increase of cytogenetic abnormalities, expressed as significantly increased mitotic aberrations, while mitotoxicity (as % embryos lacking active mitoses) was observed in embryos exposed to PS, though not to PMMA. When S. granularis sperm suspensions were exposed for 10 min to PS or to PMMA (0.1 to 5 mg L -1 ), a significant decrease of fertilisation success was observed following sperm exposure to 0.1 mg L -1 PS, though not to higher PS concentrations nor to PMMA. Sperm pretreatment, however, resulted in significant offspring damage, as excess developmental defects in plutei, both following sperm exposure to PS and PMMA, thus suggesting transmissible damage from sperm pronuclei to the offspring. The overall results point to relevant developmental, cytogenetic and genotoxic effects of PS and PMMA microplastics to S. granularis early life stages, warranting further investigations of other microplastics and other target biota.