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Microplastics are ubiquitous in aquatic environments, and in most marine environments, copepods are the main metazoans. The ingestion of microplastics by zooplankton is linked to various stresses, including oxidative stress, reduced reproductive capacities, and even mortality in nauplii. Microplastics are also reported to serve as vectors for hydrophobic contaminants. Our experimental results highlight that the retention and contact time of microplastics in copepods is quite short. The experimental results show that Parvocalanus crassirostis and Acartia pacifica defecated 75–84% and 61–71% of ingested microplastics within 60 min of ingestion. The observation raises several questions on the hypothesis of microplastic toxicity and ecological stresses: would a 180-minute contact time result in acute toxicity reported by various workers? An interesting observation was that these two copepod species did not consume microplastics larger than 50 µm in size. Considering this fact, inventories of smaller microplastics might be more important for assessing the ecological effects of MP ingestion among primary consumers in the marine food chain. Another important aspect that this study highlights is the likely change in faecal pellet sinking velocities due to the incorporation of MPs, and faecal pellets are probably efficient vectors for MP transport in the aquatic environment.

Significant efforts have been made by the International Commission on Radiological Protection (ICRP) to establish a reliable basis of equivalent and effective doses due to radionuclides. The ICRP over years has been updating the dose coefficients to include recent developments and make it more realistic. This perspective highlights some issues that warrant updating the methodology used for estimating 210Po dose to humans. The need to underpin these dose coefficients with ever-increasing literature has encouraged us to share the observation on the significant loss of 210Po due to seafood cooking, considering the loss due to cooking warrants changing the factor for the dose from seafood ingestion. Most dose assessment approaches use whole-body concentration, while most 210Po is present in the liver and digestive system that often are not part of the edible portion. The other factor is the extremely high 210Po concentration in aerosols as a result of coal and oil-fired power plants, forest fires, and volcanic activities, especially in the inhalable fraction. The 210Po/210Pb concentration ratio in the Gulf was observed to be between 1.6 and 1.9 in contrast to the 0.1 ratio observed in non-impacted areas. This reassessment of the inhalation dose is also relevant globally due to increasing incidences of forest fires where a much higher than 0.1 210Po/210Pb ratio is expected and will result in a significant inhalation dose.