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Periodontitis is a common condition characterized by a bacterial infection and the disruption of the body's immune-inflammatory response, which causes damage to the teeth and supporting tissues and eventually results in tooth loss. Current therapy involves the systemic and local administration of antibiotics. However, the existing treatments cannot exert effective, sustained release and maintain an effective therapeutic concentration of the drug at the lesion site. Hydrogels are used to treat periodontitis due to their low cytotoxicity, exceptional water retention capability, and controlled drug release profile. Hydrogels can imitate the extracellular matrix of periodontal cells while offering suitable sites to load antibiotics. This article reviews the utilization of hydrogels for periodontitis therapy based on the pathogenesis and clinical manifestations of the disease. Additionally, the latest therapeutic strategies for smart hydrogels and the main techniques for hydrogel preparation have been discussed. The information will aid in designing and preparing future hydrogels for periodontitis treatment.

Organophosphate triesters (tri-OPEs) have recently been widely identified in aquatic ecosystems, but information on their organophosphate diester (di-OPE) metabolites is sparsely available. Herein, uniform fishmeal products were collected across the globe (the U.S., China, Europe, South America, and Southeast Asia). Sixteen representative tri-OPEs and eight di-OPEs were investigated to reveal whether industrial production, metabolism, environmental persistence, or physicochemical properties are the key factors influencing their environmental burden and distribution. Tri-OPEs and di-OPEs were 100% detected in fishmeal, with bis(2-chloroethyl) hydrogen phosphate (BCEP) and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) at discernible levels in marine fauna for the first time. Average concentration of di-OPEs (49.6 ± 27.5 ng/g dw) was of the same order of magnitude as that of tri-OPEs (59.3 ± 92.2 ng/g dw). Geographical-specific distributions of tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), triphenyl phosphate (TPhP), tris(2-butoxyethyl) phosphate (TBOEP), and 2-ethylhexyl diphenyl phosphate (EHDPP) were statistically significant ( p < 0.05). Mean concentration ratios ranged from 0.087 for the BCEP-TCEP pair to 507 for the dimethyl phosphate (DMP)-trimethyl phosphate (TMP) pair. Only the TPhP-diphenyl phosphate (DPhP) pair presented a strong positive linear correlation ( r = 0.731; p < 0.01), and DPhP was proved a degradation origin. Commercial sources had a significant overall impact on distribution patterns of the DMP-TMP and the dibutyl phosphate (DnBP) - tri- n -butyl phosphate (TnBP) pairs, whereas biotic transformation and abiotic stability profoundly influenced the bis(2-ethylhexyl) phosphate (BEHP)-tris(2-ethylhexyl) phosphate (TEHP), the bis(1-chloro-2-propyl) phosphate (BCIPP)-TCIPP, and the BCEP-TCEP pairs. Di-OPEs are critical to understand environmental behavior of tri-OPEs in marine fauna.

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), and polychlorinated naphthalenes (PCNs) were determined in workplace air from eight secondary nonferrous metal processing plants to investigate occupational exposure to these toxic compounds. The total estimated daily intakes of PCDD/Fs and dl-PCBs for workers by inhalation in the workplace were in the range of 0.15-9.91 and 0.13-8.59 pg of WHO-TEQ/kg of body weight (bw) for moderate and light activities, respectively. The daily inhalation doses for workers in the workplaces of three investigated plants exceeded the tolerable daily intake recommended by the World Health Organization. These results indicate that the risk of occupational exposure to dioxins by inhalation in the workplace of plants investigated was considerably high. For PCNs, the daily inhalation doses for workers in the workplace were in the range of 0.005-4.46 and 0.004-3.87 pg of TEQ/kg of bw for moderate and light activities, respectively, which were lower than those of dioxins. To identify the source of PCDD/Fs, PCBs, and PCNs in workplace air, their homologue profiles were compared with those in stack gas from the plants investigated. It was found that significant dioxin contamination in workplace air was mainly attributed to the emission of fugitive gas from smelting furnaces during reclamation processes.

To improve understanding of human background exposure to dioxins, the influence of cooking on dioxin concentrations in food has received much attention. Studies have focused on changes in the distribution of dioxins that originate from raw foods. However, the possibility of dioxin formation during cooking has been neglected. In this study, cooking experiments were designed to investigate the generation of dioxins during cooking at high temperature and with flavorings containing organic chlorine. Solid, liquid, and gas phase samples were collected during cooking. The results indicate that dioxins can be generated during some cooking processes, such as burning, or when cooking with reactive organic chlorides, and the dioxins are more likely to be present in the smoke (gas phase) than the edible portion (solid and liquid phases). Thus, more attention should be given to cooking of raw foods and organic chlorine-containing flavorings at high temperature. Maintaining good ventilation during cooking is also necessary to reduce human exposure risk to dioxins.