Individual and combined multigenerational effects induced by polystyrene nanoplastic and glyphosate in Daphnia magna (Strauss, 1820).

In this study, the acute and multigenerational effects of the individual and combined toxicity of polystyrene nanoplastic (PSNP - 15.6, 31.2 62.5, 125, 250 and 500 mg/L) and glyphosate (Gly - 6.2, 12.5, 25, 50, 100 and 200 mg/L) on the freshwater crustacean Daphnia magna were investigated. The acute toxicity interactions were predicted mathematically using Abbott's model and multiple toxicological endpoints. In the multigenerational tests, we evaluated the effects in filial (F1 and F2) generations of daphnids after parental (F0) exposure to Gly and PSNP, as individual compounds and as a mixture, during their life history. Based on Abbott's model, the combined individual toxicities of Gly and PSNP are increased when they are present as a mixture. This indicates synergy between the components of the mixture, especially in the case of co-exposure to Gly and PSNP in higher equitoxic proportions. The mixture of PSNP and Gly caused an increase in immobility and ROS production and decrease in swimming activity. Multigenerational responses indicated that the exposure of F0 daphnids to Gly and PSNP as a mixture induced effects in the F1 and F2 reproduction parameters in the recovery tests. Thus, the results reported herein provide important information on the interaction of hydrophilic organic and nanoplastic pollutants in aqueous ecosystems. This will be useful in future studies on the toxicity of mixtures and multigenerational effects and provide a basis for management decisions aimed at the protection of environmental health.

Multigenerational Toxic Effects on Daphnia magna Induced by Silver Nanoparticles and Glyphosate Mixture.

Multigenerational toxicological effects of a binary mixture of silver nanoparticles (AgNPs) with glyphosate were identified in Daphnia magna using acute and chronic toxicity tests. Acute toxicity interactions were analyzed with the Abbott method. In the chronic tests, the survival, growth, reproduction, and age at first brood were evaluated for the parents and the exposed (F1E) and non-exposed (F1NE) descendants. The scales tested for binary mixture, at the acute level, presented antagonistic and additive interactions, possibly associated with the complexation of the AgNPs by glyphosate. Multigenerational chronic effects related to the parameters, reproduction, and age at first brood were observed in the descendants tested with the individual compounds, with no recovery for F1E and F1NE. In organisms exposed to binary mixture, there was a delay in the age at first brood and also a significant change in the reproduction parameter, with a strong reduction for the parents, F1E, and F1NE, indicating a higher toxicity than the compounds tested individually. Although the results for acute interactions between AgNP and glyphosate did not provide clear evidence, multigenerational chronic binary mixture trials have resulted in unexpected toxicity compared with individual treatments, increasing the concerns associated with this co-exposure in other scenarios. Therefore, the interaction of binary mixture with the organisms merits further investigation and the results reported in the present study will be useful in this regard. Environ Toxicol Chem 2021;40:1123-1131. © 2020 SETAC.

Probabilistic model for assessing occupational risk during the handling of nanomaterials.

Exposure to nanomaterials (NMs) can be considered as human, occupational or environmental. Occupational exposure may be experienced by the workers and/or researchers who develop and produce these products and the hazards inherent to exposure are not yet fully known. Quantitative and qualitative methods are available to estimate the occupational risks associated with the handling of NMs, however, both have limitations. In this context, the objective of this study was to create a Bayesian network (BN) that will allow an assessment of the occupational risk associated with the handling of NMs in research laboratories. The BN was developed considered variables related to exposure, the hazards associated with NMs and also the existing control measures in the work environment, such as collective protection equipment (CPE), administrative measures and personal protection equipment (PPE). In addition to assessing the occupational risk, simulations were carried out by the laboratory manager to obtain information on which actions should be taken to reduce the risk. The development of a BN to assess the occupational risk associated with the handling of NMs is a novel aspect of this study. As a distinctive feature, the BN has measurement control variables in addition to considering CPE, administrative measures and PPE. An advantage of this network in relation to other risk assessment models is that it allows the easy execution of simulations and provides a guide for a decision making by identifying which actions should be taken to minimize the risk.

Toxicological Evaluation and Quantification of Ingested Metal-Core Nanoplastic by Daphnia magna Through Fluorescence and Inductively Coupled Plasma-Mass Spectrometric Methods.

There are few studies on nanoplastic that propose quantification of the amount ingested combined with evaluation of the toxic effects on aquatic organisms. We propose 2 methods to quantify the amount of polystyrene nanoplastic (PSNP) ingested by Daphnia magna: fluorescence intensity, where a fluorescent monomer (F) is added to the PSNP and quantified through fluorescence light microscopy, and total aluminum quantification, where PSNP is synthesized with Al2 O3 metal-core nanoparticles and used for quantification of the nanoplastic ingested by the organism Daphnia magna using inductively coupled plasma-mass spectrometry. In addition, the PSNP was functionalized with palmitic acid to simulate the environmental conditions leading to biological and chemical transformations. Acute and chronic toxicity tests were performed with fluorescent PSNP (PSNP/F) and palmitic acid-functionalized PSNP/F (PSNP/F-PA). The ingestion quantified was higher by factors of 2.8 and 3.0 for PSNP/F-PA and 1.9 and 1.7 for PSNP/F applying the fluorescence intensity and total Al quantifying methods, respectively, when compared to PSNP. These results are consistent with the data obtained in the toxicity tests, which showed an approximately 3 times increase in the adverse effect of PSNP/F-PA on the mobility and reproduction of the organisms. Thus, the strong inhibition of D. magna reproduction caused by PSNP/F-PA in the chronic toxicity tests could be associated with a greater amount of this nanoplastic being ingested by the organisms. Environ Toxicol Chem 2019;38:2101-2110. © 2019 SETAC.