Mutagenicity and metabolism of dimethyl phthalate and its binding to epidermal and hepatic macromolecules

Priority Organic Pollutant Monitoring Inventory and Relative Risk Reduction Potential for Solid Waste Incineration

Incineration is a promising sustainable treatment method for solid waste. However, the ongoing revelation of new toxic pollutants in this process has become a controversial issue impeding its development. Thus, identifying and regulating high-risk pollutants emerge as pivotal strides toward reconciling this debate. In this study, we proposed a workflow aimed at establishing priority monitoring inventories for organic compounds emitted by industries involving full-component structural recognition, environmental behavior prediction, and emission risk assessment, specifically focusing on solid waste incineration (SWI). A total of 174 stack gas samples from 29 incinerators were first collected. Nontarget full organic recognition technology was then deployed to analyze these samples, and 646 organic compounds were identified. The characteristics, i.e., toxicity effects, toxicity concentrations, persistence, and bioaccumulation potential, of these compounds were assessed and ranked based on the TOXCAST database from the US Environmental Protection Agency and structural effect models. Combined with consideration of changes in seasons and waste types, a priority control inventory consisting of 28 organic pollutants was finally proposed. The risks associated with SWI across different regions in China and various countries were assessed, and results pinpointed that by controlling the priority pollutants, the average global emission risk attributed to SWI was anticipated to be reduced by 71.4%. These findings offer significant guidance for decision-making in industrial pollutant management, emphasizing the importance of targeted regulation and monitoring to enhance the sustainability and safety of incineration processes.

Mutagenicity evaluation to UV filters of benzophenone-6, benzophenone-8, and 4-methylbenzylidene camphor by Ames test

Benzophenone (BPs) and 4-Methylbenzylidene Camphor are used as ultraviolet (UV) filters to protect the skin and hair in personal care products. The discharging of the three chemicals may endanger the receiving water ecosystem. In the present study, the mutagenicity of BP-6, BP-8, and 4-Methylbenzylidene Camphor was tested using the Salmonella typhimurium reverse mutation test (Ames test) in the system with and without rat liver microsomal preparations (S9). Four S.typhimurium strains, TA97, TA98, TA100, and TA102 were employed in the Ames tests. The mutagenicity was detected from all three chemicals. The addition of S9 increased the mutation ratios of three chemicals to four strains, except BP-6 to TA100 strain and 4-MBC to TA97 and TA98 strain. In the mixed experiment, all positive effects were detected in the absence of S9. However, the results all became negative in the presence of S9. For the mixture of BP-6 and 4-MBC, positive results were detected on four tester strains except for the TA100 strain. For the mixture of BP-6, BP-8, and 4-MBC, positive results were detected on four strains. The mixture test results showed antagonism in mutagenicity for the mixture of BP-6 and 4-MBC to TA98 and TA100 strains and the mixture of BP-6, BP-8, and 4-MBC to TA100 and TA102 strains.

Evaluation by the Ames Assay of the Mutagenicity of UV Filters Using Benzophenone and Benzophenone-1

Ultraviolet absorbing chemicals (UV filters) are widely used in personal care products for protecting human skin and hair from damage by UV radiation. Although these substances are released into the environment during production and consumption processes, little is known about their genotoxicity effects. Our previous studies have shown that benzophenone-type UV filters exhibited acute toxicity on three species of aquatic organisms. Mutagenesis by benzophenone (BP) and benzophenone-1(BP-1) was tested in the present study by the Salmonella typhimurium/reverse mutation assay (Ames assay). All the positive reverse mutations occurred in the absence of the S9 liver extract system for both chemicals. From BP, positive mutation effects on the TA102 strain at doses of 0.05 μg/plate and 0.5 μg/plate were detected. From BP-1, positive mutation effects on the TA97 strain at doses of 0.05 μg/plate and 0.5 μg/plate, and on the TA100 strain at a dose of 0.5 μg/plate, were detected. A mixture of BP and BP-1 exhibited mutagenicity on the TA97 and TA100 strains. For the TA97 strain, the positive mutation results were detected at 10% and 50% of the mixture. For the TA100 strain, the results were detected when the mixture was at 5% and 10%. In the mixture at 5%, the concentrations of BP and BP-1 were 3.5 μg/plate and 14 μg/plate, respectively. In the 10% mixture, the doses of BP and BP-1 were 7 μg/plate and 28 μg/plate, respectively. In the 50% mixture, the doses of BP and BP-1 were 35 μg/plate and 140 μg/plate, respectively. The mixture test results suggested that there was antagonism in mutagenicity between BP and BP-1.

Distribution of Phthalate Metabolites between Paired Maternal-Fetal Samples

Phthalic acid esters (PAEs) are readily metabolized to phthalate metabolites (mPAEs) in the human body. The occurrence of mPAEs in adult human samples is well documented; however, the maternal-fetal transmission of mPAEs has seldom been studied. In this study, 78 paired maternal-fetal samples, including maternal urine (MU), maternal serum (MS), cord serum (CS), and amniotic fluid (AF), were collected from pregnant women in Tianjin, China. Seven mPAEs were detected in MS, CS, and AF, whereas all 11 investigated mPAEs were found in MU. The median concentration of ∑mPAEs was the highest in MU (128 ng/mL, with a range of 20.2-973 ng/mL), and proceeded in the order of CS (44.9, 13.9-315 ng/mL), MS (24.6, 3.75-156 ng/mL), and AF (10.4, 7.69-79.8 ng/mL). The values of ∑mPAEs and several individual mPAEs were significantly correlated between MU and MS, with generally higher concentrations in MU, which indicated that urinary mPAEs is a good indicator of PAEs' exposure in adults. Notably, the median CS:MS ratios of ∑mPAEs (1.58) were higher than 1, indicating that fetuses were exposed to mPAEs before birth. Significant correlations were also observed between MS and CS, which suggested that mPAEs in MS provide an indication of the fetal exposure. This study presents the first systematic analysis of the distribution and transmission of various mPAEs between mothers and fetuses.

Effect of some phthalate esters in human cells in the comet assay

Phthalate esters are among the most extensively used industrial chemicals and are widely distributed in the environment. Di-(2-ethylhexyl)phthalate (DEHP) and its hydrolysis product mono-(2-ethylhexyl)phthalate (MEHP) have been examined for genotoxic activity on previous occasions. Only MEHP was found to cause chromosome damage in CHO cells but was without effect in the sister chromatid exchange and hypoxanthine guanine phosphoribosyl assay. DEHP was found to be a weak direct acting mutagen in Salmonella typhimurium strain TA100, the mutagenic activity of which could be abolished by rat liver microsomes (S9 mix). The clastogenicity and weak mutagenicity suggest a possible contributory role for these compounds in the observed carcinogenicity of the phthalates, which have been thought predominantly to be linked to cancer pathology through proliferation of hepatic peroxisomes. The present study showed that these compounds could produce DNA damage in human blood cells in the Comet assay and also, that rat liver microsomes could abolish the effect of DEHP. Thus in the intact animal, no response may be observed.