Intervention research on influence of biomass briquette on human health

Raw coal (RC) is the main fuel in many, especially rural parts of China. Biomass briquette (BB), which has less SO₂ emission, was developed as a cleaner alternative for RC. In this research, the cooking fuel of a group of countrywomen was switched from RC to BB and studied for health effects. Five biological indices percent of comet cell (COMET), lysozyme saliva (LYS), malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) were chosen. All indices were measured three times during the 18-month experiment. Statistical analysis shows that there are significant changes in the indices. Using BB as a cooking fuel improves the function of anti-oxidation system and the nonspecific immune system, and reduces the DNA damage, which is negatively related to LYS and SOD.     

Modeling toxic endpoints for improving human health risk assessment of polycyclic aromatic hydrocarbons – parent compounds and simple mixtures

Risk assessments for mixtures of polycyclic aromatic hydrocarbons (PAH) are problematic due to the lack of available potency and toxicity data on individual compounds and mixtures. This article examines the toxicity of parent compounds and designed mixtures of PAH in order to bridge the gap between component assessment and mixture assessment for this class of ubiquitous compounds. The objective for this study was to test seven parent PAH compounds and four PAH mixtures in a set of three bioassays to evaluate the toxicity of parent compound PAH and binary mixtures of PAH. PAH and mixtures were examined in the Salmonella/microsome mutagenicity assay, a Gap Junction Intercellular Communication assay, and the 7-ethoxyresorufin-O-deethylase assay. These assays were chosen for their ability to measure specific toxic endpoints related to the carcinogenic process (i.e. initiation, promotion, and progression). Two compounds similar in structure, benzo(a) pyrene (BAP) and benzanthracene, consistently produced positive results in all three bioassays. Conversely, a linear PAH, anthracene, produced negative results in all three bioassays. An antagonistic response was observed for the mixtures in all three bioassays. Chemical structure was important in explaining the observed responses. Using chemical structure–activity relationships with the steps of the carcinogenic process may be used to improve estimates of toxicity for compounds and mixtures for human health risk assessments.     

Genotoxic assessment of anthracene and benzo [a] pyrene to milkfish Chanos chanos

Mutagenic and genotoxic effects of polycyclic aromatic hydrocarbons, anthracene and benzo [a] pyrene (BaP), in milkfish Chanos chanos were determined using micronucleus (MN) test and comet assay (CA). Distinct mean frequencies of nuclear abnormalities such as MNs; binucleated micronuclei, nuclear bud, and fragmented apoptotic cells were measured. Significant increase in DNA damage with five classes of damage level was observed and expressed in terms of arbitrary unit (AU). Mean frequencies of total nuclear abnormalities were 0.5?±?0.25 cells in control; 0.67?±?0.33 cells in solvent control; 70?±?9.60 cells in 0.176?mg?L^?1 anthracene, and 91.83?±?6.25 cells in 0.031?mg?L^?1 BaP. The greatest DNA damage of 170AU was observed in 0.176?mg?L^?1 anthracene-exposed group and 182AU was observed in 0.031?mg?L^?1 BaP-treated fish. This study confirmed that the CA and MN assays are useful tools in determining potential genotoxicity of water pollutants and might be appropriate as a part of monitoring program.     

Molecular level toxicological evaluation of a dental composite implanted in albino rats

Dental composite (DC) resins are synthetic resins which are used as restorative material or adhesives in dentistry. Monomers and other components released into the oral environment from the DC material even after polymerization might affect the surrounding tissues and even the whole body gradually. Biocompatibility of DC has to be stringently evaluated since the fillings are in close contact with mucosa, tooth, and pulp. Common difficulties with various current dental materials include allergies, chemical leakage from the material, and pulpal irritation which are due to the byproducts of chemical reactions during different stages of material hardening. Dental Products Laboratory of Sree Chitra Tirunal Institute for Medical Sciences and Technology developed a new BIS-GMA-based DC. In this study the oxidative stress induced by this DC material in vivo was tested for a period of 1, 4, 8, 26, or 52 weeks in albino rats. Dental materials were implanted intramuscularly into the gluteus muscle and oxidative biomarkers such as lipid peroxidation, 8-oxo-deoxyguanosine (8-OHdG) concentration, and total glutathione content analyzed. Data showed no significant changes in antioxidant defense system and 8-OHdG levels in nuclear DNA of the tissue. Serum biochemical results confirmed that animals were in normal functioning physiological state.     

Effect of fomesafen on glutathione S-transferase and cellulase activity and DNA damage in the earthworm (Eisenia fetida)

Biochemical responses and DNA damage of earthworm (Eisenia fetida) exposed to various concentrations of fomesafen (0, 10, 100, and 500 μg kg^?1) for 3, 7, 14, 21, and 28 days were investigated in vivo. Glutathione S-transferase (GST) activity was significantly stimulated upon treatment with 500 μg kg^?1 fomesafen for 21 days, while the cellulase activity was markedly inhibited after 14 days of treatment. On day 28, the activities of GST and cellulase had recovered to the level similar to that of controls. Low or mild DNA damage in earthworm was induced within 14 days of exposure, and the damage was reduced or disappeared with the extension of exposure.     

Statistical analysis of bioassays,based on hazard modelling

A stochastic model is proposed to describe time-dependent lethal effects of toxic compounds. It is based on simple mechanistic assumptions and provides a measure for the toxicity of a chemical compound, the so-called killing rate. The killing rate seems a promising alternative for the LC50. The model also provides the no-effect level and the LC50, both as a function of exposure time. The model is applied to real data and to simulated data.     

Comparative cytotoxicity of nanoparticles and ions to Escherichia coli in binary mixtures

The objective of this study was to understand toxicity of mixture of nanoparticles (NPs) (ZnO and TiO₂) and their ions to Escherichia coli. Results indicated the decrease in percentage growth of E. coli with the increase in concentration of NPs both in single and mixture setups. Even a small concentration of 1 mg/L was observed to be significantly toxic to E. coli in binary mixture setup (exposure concentration: 1 mg/L ZnO and 1 mg/L TiO₂; 21.15% decrease in plate count concentration with respect to control). Exposure of E. coli to mixture of NPs at 1000 mg/L (i.e., 1000 mg/L ZnO and 1000 mg/L TiO₂) resulted in 99.63% decrease in plate count concentration with respect to control. Toxic effects of ions to E. coli were found to be lesser than their corresponding NPs. The percentage growth reduction was found to be 36% for binary mixture of zinc and titanium ions at the highest concentration (i.e., 803.0 mg/L Zn and 593.3 mg/L Ti where ion concentrations are equal to the Zn ions present in 1000 mg/L ZnO NP solution and Ti^+ 4 ions present in 1000 mg/L TiO₂ NP solution). Nature of mixture toxicity of the two NPs to E. coli was found to be antagonistic. The alkaline phosphatase (Alp) assay indicated that the maximum damage was observed when E. coli was exposed to 1000 mg/L of mixture of NPs. This study tries to fill the knowledge gap on information of toxicity of mixture of NPs to bacteria which has not been reported earlier.     

苯并[a]芘和菲对缢蛏血细胞DNA损伤的研究

为研究苯并[a]芘和菲对缢蛏的毒性效应,将缢蛏(Sinonovacula constricta)分别暴露于浓度为0.45 mg·L-1、0.15 mg·L-1、0.05 mg·L-1苯并[a]芘溶液和0.45 mg·L-1、0.15 mg·L-1、0.05 mg·L-1菲的溶液中,采用单细胞凝胶电泳实验(彗星实验)技术检测不同暴露时间缢蛏血淋巴细胞的DNA损伤程度,对照组为清洁海水。结果显示,高浓度(0.45 mg·L-1)苯并[a]芘溶液和(0.45 mg·L-1)菲溶液在短期(7 d)内即可导致缢蛏血细胞显著的DNA损伤,并且随苯并芘[a]和菲浓度的增大和暴露时间的延长,DNA损伤程度增加。21 d恢复实验后,各浓度组DNA损伤又均有不同程度的恢复,但中高浓度组(0.45 mg·L-1和0.15 mg·L-1)与对照组仍显著性差异。两种多环芳烃物质对缢蛏血细胞的DNA损伤作用均存在较显著时间-剂量-效应关系。其中,苯并芘[a]对缢蛏血细胞的DNA损伤作用要高于菲。     

彗星实验技术及其应用

彗星实验是瑞典科学家Ostling和Johanson于1984年发明的检测毒物DNA损伤效应的方法。它经历了从最初的微电泳技术、中性彗星实验、碱性彗星实验、酶切彗星实验和双向垂直彗尾彗星实验等不断完善的发展过程。在毒理学、遗传学和环境生态科学等领域有着重要的应用,是经济合作与发展组织(OECD)和欧洲食品安全局等国际组织推荐的测定遗传毒性的方法之一。彗星实验的关键点包括单细胞悬液的制备、细胞裂解液的成分与比例,低熔点琼脂糖凝胶的浓度,电泳条件等。在典型应用领域,如蚯蚓、鱼、两栖动物、鼠和人的彗星实验很难找到标准实验方案。成功的彗星实验还需关注,实验设计时必须包括阳性对照,结果表述时必须有图为证,实验方案可能因物种或细胞而异。     

纳米MnO2与常规MnO2粉末对Hela细胞DNA损伤的对比研究

为探讨纳米MnO2与常规MnO2粉末对细胞DNA损伤作用的差别,采用不同浓度的纳米MnO2与常规MnO2粉末(0、100、200、400μg·mL-1)对Hela细胞进行染毒,应用单细胞凝胶电泳(彗星实验)检测Hela细胞的损伤效应.结果表明,与对照组相比,纳米MnO2和常规MnO2各染毒组细胞尾部DNA百分率(TailDNA%)和尾矩(TailMoment)均显著增加(p<0.01);同一浓度下,纳米MnO2组细胞尾部DNA百分率和尾矩显著高于常规MnO2组(p<0.01).以上结果表明,纳米MnO2和常规MnO2粉末均能导致Hela细胞DNA损伤,且纳米MnO2的损伤作用强于常规MnO2.