Mitochondrial damage and apoptosis: Key features in BDE-153-induced hepatotoxicity.

Brominated flame retardants are used in consumer goods to increase product resistance to fire and/or high temperatures. Polybrominated diphenyl ethers (PBDEs) are the most commonly employed class of brominated flame retardants because they are inexpensive and can effectively prevent flame from spreading. PBDEs are persistent, can bioaccumulate, are transported over long distances, and display toxicity. However, their toxic mechanisms of action have not been well established. Because mitochondria are recognized as the main energy-producing cell organelle and play a vital role in cellular function maintenance, here we apply mitochondria as an experimental model to evaluate the toxic effects of the PBDE congener BDE-153 (Hexa-BDE) at concentrations ranging from 0.1 to 25 µM. We also assess BDE-153 cytotoxicity to HepG2 cells in order to elucidate its mechanisms of toxicity. Exposure to BDE-153 affects isolated mitochondria: this congener can interact with the mitochondrial membrane, to dissipate the membrane potential and to induce significant ATP depletion. Furthermore, BDE-153 can diminish MTT reduction and cell proliferation and can interfere in cell cycle, as evaluated in cell cultures. These cytotoxic effects are related to mitochondrial dysfunction due to mitochondrial membrane potential dissipation and reactive oxygen species accumulation. These effects result in apoptotic cell death, as demonstrated by phosphatidylserine maintenance on the cell membrane external surface, nuclear condensation and fragmentation, and presence of pro-apoptotic factors such as cytochrome c and Apoptosis-inducing Factor (AIF) plus caspase 3 activation in the cytosol. Together, our results show PBDEs can induce cytotoxicity, reinforcing the idea that these compounds pose a risk to the exposed population.

The herbicides trifluralin and tebuthiuron have no genotoxic or mutagenic potential as evidenced by genetic tests.

Brazil has been the largest world consumer of pesticides since 2008, followed by the USA. The herbicides trifluralin and tebuthiuron have been widely applied in agriculture. These herbicides are selective for some plant species, and their use brings various benefits. However, the genotoxic and mutagenic effects of tebuthiuron on non-target organisms are poorly known, and in addition, the effects of trifluralin must be better investigated. Therefore, this study employed genetic tests including the comet assay and micronucleus test to evaluate the genotoxic effects of trifluralin and tebuthiuron on HepG2 cells. In addition, we have used the Ames test to assess the mutagenic effects of the herbicides on the TA97a, TA98, TA100, and TA1535 strains of Salmonella typhimurium. On the basis of the comet assay and the micronucleus test, trifluralin did not cause genetic damage to HepG2 cells. In addition, trifluralin did not impact the tested S. typhimurium strains. Regarding tebuthiuron, literature has shown that this herbicide damaged DNA in Oreochromis niloticus. Nevertheless, we have found that tebuthiuron was not genotoxic to either HepG2 cells or the S. typhimurium strains. Therefore, neither trifluralin nor tebuthiuron exerted genotoxic or mutagenic potential at the tested conditions.

Comparative Study of Genotoxicity Induced by Six Different PBDEs.

Indiscriminate use of synthetic substances has led to environmental contamination and increasing human and animal exposure to harmful chemicals. Polybrominated flame retardants (PBDEs), which serve as non-covalent additives that enhance the safety of a variety of commercial and consumer goods, are an important class among potentially damaging synthetic substances. Its use is very common in developing countries, including Brazil. In theory, 209 different PBDE congeners exist, and many are currently being used during the manufacture of several products. Unfortunately, PBDEs are easily released from the original products, promptly reaching the environment. Knowledge about the toxicological power of these substances is still limited, which has prevented environmental and regulatory authorities from conducting adequate risk assessments. This research addresses the genotoxic and mutagenic potential of PBDEs. The effects of HepG2 cells and Salmonella typhimurium exposure to six main representatives of PBDEs, namely tetrabromodiphenyl ether (BDE-47), pentabromodiphenyl ether (BDE-99 and BDE-100), hexabromodiphenyl ether (BDE-153 and BDE-154) and decabromodiphenyl ether (BDE-209), were evaluated. The comet assay revealed that all the assessed BDEs exerted genotoxic effects but induced no micronuclei formation in HepG2 cells. These BDEs had no significant mutagenic effects on the Salmonella typhimurium strains TA98 and TA100. Taken together, the results of the genomic instability assays showed that PBDEs can represent a risk to the health of directly and indirectly exposed population, because the assessed BDEs induce genotoxic effects in the HepG2 cell line.

A perspective on the potential risks of emerging contaminants to human and environmental health.

Technological, agricultural, and medical advances have improved the lifestyle of humankind. However, these advances have caused new problems that affect the environment and future generations. Emerging contaminants display properties such as low degradation potential and environmental persistence. In addition, most contaminants are lipophilic, which culminates in high bioaccumulation. The disposal of pharmaceuticals and personal care products into the environment underlies microbial and bacterial resistance. Plasticizers change several characteristics of industrialized materials, such as flexibility, but they are potentially carcinogenic and disrupt the endocrine system. Pesticides prevent the propagation of numerous kinds of pests; nevertheless, they exert neurotoxic and mutagenic effects, and they impact the environment negatively. Addition of flame retardants to a number of materials prevents flame propagation; however, after their release into the environment, these chemicals may bioaccumulate in organisms and disrupt the endocrine system, too. Surfactants can change the surface and interfacial properties of liquids, but their presence in the environment can interfere with countless enzymes and can even impair the endocrine system of various organisms and induce the feminization of species. Hence, gaining knowledge about emerging contaminants is increasingly important to minimize future damage and enable proper monitoring of each class of compounds in the environment which will help to improve legislation on this matter.

Analysis of the procedures used to evaluate suicide crime scenes in Brazil: a statistical approach to interpret reports.

This study uses statistical techniques to evaluate reports on suicide scenes; it utilizes 80 reports from different locations in Brazil, randomly collected from both federal and state jurisdictions. We aimed to assess a heterogeneous group of cases in order to obtain an overall perspective of the problem. We evaluated variables regarding the characteristics of the crime scene, such as the detected traces (blood, instruments and clothes) that were found and we addressed the methodology employed by the experts. A qualitative approach using basic statistics revealed a wide distribution as to how the issue was addressed in the documents. We examined a quantitative approach involving an empirical equation and we used multivariate procedures to validate the quantitative methodology proposed for this empirical equation. The methodology successfully identified the main differences in the information presented in the reports, showing that there is no standardized method of analyzing evidences.