Organic rubber additives in automobile tire listed up as PRTR chemicals are potential hazards to give adverse effects on the environment. Therefore, it is important to evaluate the behavior of these chemicals in the environment. The purpose of this study was to clarify their fate and concentration in the environment and evaluate their risks to human health and environmental organisms.
The result of exposure tests verified that unstable bond of the organic rubber additives could be split during exposure, though the chemical structures were maintained in the tire rubber.
N-Cyclohexylbenzothiazole-2-sulphenamide (CBS) and N-(1,3-Dimethylbutyl)-N′-phenyl-1,4-phenylenediamine (DMPPD) contained in tire rubbers in high concentrations were found in the atmospheric particles, water and sediment. CBS and DMPPD concentrations were high in the sediment at the outlet spots of wastewater from overhead road. It has been clarified that the tire dust burdens environment with the load of organic rubber additives in automobile tire.
Risk assessment for the aquatic environment which was based on margin of exposure (MOE) and product of uncertainty factors (UFs) indicated that no adverse effects on environmental organisms in the river water were anticipated by the organic rubber additives and their degradation products for the moment, though the MOE value for DMPPD was less than UFs in the wastewater samples from overhead load.
Risk assessment for human health which was based on MOE and UFs indicated that there was no human risk by the organic rubber additives and their degradation products for the moment.

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13 kind of Perfluorinated compounds (PFCs) in the mainstream of Tamagawa River and its inflows (tributaries, and effluents from Sewage Treatment Plants) were analyzed, and the loads of PFOS, PFOA and other 4 compounds were evaluated. The concentrations of PFOS and PFOA were found to be much lower than those of 2005 since 2009. This result indicates that the Stockholm Convention on Persisitent Organic Pollutants (POPs) and 2010/2015 PFOA Stewardship Program are effective. The cumulative load of PFCs that was accumulated in the inflows sequentially from Nagata Bridge, as the uppermost point in this study, closely resembled the measured load at each sampling point in Tamagawa River. These results indicate that PFCs were scarcely degraded, volatilized, during flow down the river. The ratio of PFCs with longer chain length such as PFUnDA and PFTrDA in sediment samples were much higher than those of water ones.

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The aim of this study was to develop a new type of adsorbent that can sink to the bottom of a body of water, adsorb pollutants there, and then float up on the surface of water to be collected easily. The purpose could be achieved by controlling the specific gravity of alginate gel beads by adding CO₂ gas bubbles as a float and calcium carbonate (CaCO₃) salts as a weight, and by the dissolution of the CaCO₃ in the gel beads. The floating time of the alginate gel beads, which is a time necessary to float up on the surface of water after adding them to water, depended on the amount of salts and the amount and size of bubbles in the beads. When alginate gel beads containing 5 wt% of CaCO₃ were added to the solution of pH 3.0, the beads sank to the bottom of water and then floated up to the surface of the water after a delay of about 150 minutes. The floating time of the alginate gel beads increased almost linearly with increases in the amount of CaCO₃ in the bead. After the repeated additions of the alginate gel beads containing 3 wt% of CO₂ bubble and 5 wt% of CaCO₃, 98.4 wt% of total lead ions in the bottom of water could be removed. CaCO₃ added in the alginate gel bead also acted as a reagent to keep the pH of the inside of the bead basic. Therefore, even in the acidic solution, the gel beads showed the adsorption ability for lead ions.

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