Urinary levels, composition profile and cumulative risk of bisphenols in preschool-aged children from Nanjing suburb, China.

Due to the extensive use in consumer products, the bisphenols (BPs) pollution in the environments has aggravated and people are frequently exposed to BPs. In this research, four BPs, i.e., bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS) and bisphenol AF (BPAF), were determined in urine samples collected from Gaochun District preschool-age children and the concentrations, distribution profiles, potential sources and cumulative risk assessment of the target compounds were studied. Total concentrations of 4 BPs ranged from 2 to 3113.1 ng/L, with the average concentration of 648.6 ng/L. BPA was the predominant congener (accounting for 94%), followed by BPS. Correlation analysis indicated a negative relationship between BPA and BPAF (R = -0.273, p < 0.05). The estimated daily intakes suggested that young females were more sensitive to BPs. Moreover, the cumulative risk for hazard quotient (HQ) of BPA has been evaluated and the results showed that no high risk had occurred. It provided basic information on the occurrence and human exposure to urinary BPs of preschool aged children from Gaochun District.

Correlation between antibiotic-induced feeding depression and body size reduction in zooplankton (rotifer, Brachionus calyciflorus): Neural response and digestive enzyme inhibition.

The study analyzed the correlation between the antibiotic-induced feeding depression and body size reduction in rotifer, Brachionus calyciflorus, involving exposure, post-exposure and re-exposure periods. The filtration and ingestion rates of the rotifers were inhibited in these three exposure periods at any given concentration of the antibiotic sulfamethazine (SMZ). As food for rotifer, the cell size of the green algae was unchanged, which indicated that it could not drive feeding depression. Secondly, several corresponding physiological responses were considered. Reactive oxygen species (ROS) levels increased in the post-exposure and the re-exposure; acetylcholinesterase (AChE) activity was significantly decreased in the exposure and the re-exposure, whereas it was induced in the post-exposure. The activities of amylase and lipase were always inhibited in these three exposure periods. Additionally, significant decreases in lorica length, width and biovolume of rotifers occurred after the feeding depression. Statistical analysis indicated a positive correlation between the activity of the digestive enzyme and the body size. Our results demonstrated that SMZ could influence the neurotransmission, inhibit the activity of the digestive enzyme, and finally result in body size reduction. These results provided an integrated perspective on assessing the toxicity effects of antibiotic in non-lethal dosage on the feeding behavior of non-target aquatic organisms.

Investigation of the removal mechanism of antibiotic ceftazidime by green algae and subsequent microbic impact assessment.

The present study provides an integrated view of algal removal of the antibiotic ceftazidime and its basic parent structure 7-aminocephalosporanic acid (7-ACA), including contribution analysis, bacteriostatic and aquatic toxic assessment and metabolite verification. 92.70% and 96.07% of the two target compounds was removed after the algal treatment, respectively. The algal removal can be separated into three steps: a rapid adsorption, a slow cell wall-transmission and the final biodegradation. Additionally, while ceftazidime demonstrated an excellent inhibitory effect on Escherichia coli, there was no bacteriostasis introduced after the algal treatment, which could avoid favoring the harmful selective pressure. On the other hand, no significant aquatic impact of the two target compounds on rotifers was observed and it was not enhanced after the algal treatment. To better reveal the mechanism involved, metabolite analyses were performed. Δ-3 ceftazidime and trans-ceftazidime were regarded as the metabolites of ceftazidime and the metabolite of 7-ACA was regarded as a compound which shared the similar structure with 4-chlorocinnamic acid. Our study indicated that the green algae performed a satisfactory growth capacity and played a dominant role for the biodegradation of the target antibiotics, which achieved high removal efficiency and low environmental impact.

An integrated assessment of ceftazidime and photoproducts on the feeding behavior of rotifers: From exposure to post-exposure.

Compared to traditional toxicological studies, which depict the dose-effect of contaminants themselves on organisms at the given time, the exposure and post-exposure impacts of antibiotic ceftazidime and its photoproducts are carried out to systematically evaluate the environmental risk fate of ceftazidime in aquatic environments. For the exposure process, the promotion effect of ceftazidime on the feeding behavior of the rotifers decreased when the target compound was irradiated by sunlight, and the promotion effect was converted into inhibition effect, which indicated that the highest toxicity of ceftazidime on the feeding behavior of the rotifers was found after UV-B irradiation. The overcompensation occurred in the post-exposure, indicating a short - term effect of the corresponding photoproducts on the rotifer. In order to better understand the mechanism of this change, the photodegradation pathways of the target compound was analyzed and compared. The degradation degree under the UV-B irradiation had intensified greatly than that under the nature light irradiation. The reactive oxygen species (ROS) of the rotifer in exposure and post-exposure was also detected. Ceftazidime and photoproducts induced generation of ROS, indicating that oxidative damage occurred, and the decreasing of ROS levels could be viewed as the recovery of the rotifers in the post-exposure.