Carcinogen

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effe...

Coexpression of cytochrome P450 monooxygenases (CYPs) and reductase was found in human gastric mucosa with intestinal metaplasia. Immunohistochemistry showed reactivity to P450 reductase in metaplastic epithelial cells and in pyloric gland cells in glands showing intestinal metaplasia. These cells exhibit NADPH-diaphorase activity. Reverse transcription-PCR analysis and Western blotting showed that CYP1A1 and CYP1A2 were expressed in specimens with intestinal metaplasia. Tissue distribution of CYP1A1 coincided with that of P450 reductase. However, immunoreactivity to CYP1A2 protein was localized only in the pyloric gland cells near the intestinal metaplastic gland. Salmonella typhimurium mutagen assay definitively revealed that microsomes prepared from gastric mucosa with intestinal metaplasia, in particular in the pyloric gland, functionally activated benzo(a)pyrene and 2-amino-3-methylimidazo [4,5-f]quinoline. These results indicate that carcinogen activation by CYP enzymes expres...

Fruit and vegetable consumption has consistently been associated with decreased risk of a number of aerodigestive tract cancers, including esophageal cancer. We have taken a "food-based" chemopreventive approach to evaluate the inhibitory potential of lyophilized black raspberries (LBRs) against N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in the F344 rat, during initiation and postinitiation phases of carcinogenesis. Anti-initiation studies included a 30-week tumorigenicity bioassay, quantification of DNA adducts, and NMBA metabolism study. Feeding 5 and 10% LBRs, for 2 weeks prior to NMBA treatment (0.25 mg/kg, weekly for 15 weeks) and throughout a 30-week bioassay, significantly reduced tumor multiplicity (39 and 49%, respectively). In a short-term bioassay, 5 and 10% LBRs inhibited formation of the promutagenic adduct O(6)-methylguanine (O(6)-meGua) by 73 and 80%, respectively, after a single dose of NMBA at 0.25 mg/kg. Feeding 5% LBRs also signif...

Investigations on solar-driven membrane distillation (SDMD) were carried out for removal of arsenic from contaminated groundwater. Three different types of hydrophobic membranes made of polytetrafluoroethylene (PTFE) and polypropylene (PP) with surface area of 120×10−4m2 were used as flat sheet in a direct contact membrane distillation (DCMD) set up in a cross flow module. Effects of initial arsenic concentration in the feed, feed velocity, feed temperature and distillate inlet temperature on arsenic removal efficiency and flux were studied where temperatures of feed and distillate were found to have significant effect on the flux. Almost 100% arsenic separation was achieved without wetting membrane pore even after 120h of operation. The PTFE membrane with a flux of 49.80kg/m2h was found to the best one out of the tested membranes. The study shows that solar-driven DCMD can effectively separate arsenic from groundwater using a cross flow membrane module with PTFE hydrophobic membrane.

Epidemiological studies showing a protective effect of diets rich in fruits and vegetables against cancer have focused attention on the possibility that biologically-active plant secondary metabolites exert anti-carcinogenic activity. This huge group of compounds, now collectively termed ‘phytochemicals’, provides much of the flavour and colour of edible plants and the beverages derived from them. Many of these compounds also exert anti-carcinogenic effects in animal models of cancer, and much progress has been made in defining their many biological activities at the molecular level. Such mechanisms include the detoxification and enhanced excretion of carcinogens, the suppression of inflammatory processes such as cyclooxygenase-2 expression, inhibition of mitosis and the induction of apoptosis at various stages in the progression and promotion of cancer. However, much of the research on phytochemicals has been conducted in vitro, with little regard to the bioavailability and metabol...

Contaminants such as nitrogen (N), phosphorus (P), dissolved organic carbon (DOC), arsenic (As), heavy metals, and infectious pathogens are often associated with agricultural systems. Various soil and water remediation techniques including the use of chemical amendments have been employed to reduce the risks associated with these contaminants. This paper reviews the use of chemical amendments for immobilizing principal agricultural contaminants, the chemistry of contaminant immobilization, and the environmental consequences associated with the use of these chemical products. The commonly used chemical amendments were grouped into aluminum-, calcium-, and iron-containing products. Other products of interest include phosphorus-containing compounds and silicate clays. Mechanisms of contaminant immobilization could include one or a combination of the following: surface precipitation, adsorption to mineral surfaces (ion exchange and formation of stable complexes), precipitation as salts, and co-precipitation. The reaction pH, redox potential, clay minerals, and organic matter are potential factors that could control contaminant-immobilization processes. Reviews of potential environmental implications revealed that undesirable substances such as trace elements, fluoride, sulfate, total dissolved solids, as well as radioactive materials associated with some industrial wastes used as amendment could be leached to ground water or lost through runoff to receiving water bodies. The acidity or alkalinity associated with some of the industrial-waste amendments could also constitute a substantial environmental hazard. Chemical amendments could introduce elements capable of inducing or affecting the activities of certain lithotrophic microbes that could influence vital geochemical processes such as mineral dissolution and formation, weathering, and organic matter mineralization.

Benzo[α]pyrene (BaP) is one of the most toxic
polycyclic aromatic hydrocarbons (PAHs) in the soilplant
system causing potential carcinogenicity and
mutagenicity for human health. The knowledge on the
behavior of BaP in soil-plant system as well as aqueous
environment is needed for minimizing the risk of human
exposure and environmental contamination. BaP, high
molecular weight PAH with five benzene rings has been
specifically classified as a primary pollutant and group
1 human carcinogen. Bioremediation is an eco-friendly
and cost-effective method for reclaiming the
environment contaminated with BaP by making use of
the microorganisms and plants to eradicate the
hazardous effects.
The present review is focused on the microbe assisted
bioremediation and phytoremediation techniques for
the removal of BaP from the soil and aqueous
environment. The information provided here will help
to plan the research in a better way to develop more
sustainable system for remediation of BaP from the
environment.

Groundwater arsenic contamination in Bangladesh and its adjoining part of West Bengal (India) is reported to be the biggest arsenic calamity in the world in terms of the affected population. Tossa jute, Corchorus olitorius is a popular crop of this arsenic prone population. The present study was undertaken to evaluate the protective effect of aqueous extract of C. olitorius leaves (AECO) against sodium arsenite (NaAsO2) induced cardiotoxicity in experimental rats. The animals exposed to NaAsO2 (10 mg/kg, p.o.) for 10 days exhibited a significant inhibition (p < 0.01) of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase and reduced glutathione level in myocardial tissues of rats. In addition, it significantly increased (p < 0.01) oxidized glutathione, malondialdehyde and protein carbonyl content in myocardial tissue. Treatment with AECO (50 and 100 mg/kg, p.o.) for 15 days prior to NaAsO2-intoxication significantly protected cardiac tissue against arsenic-induced oxidative impairment. In addition, AECO pretreatment significantly prevented NaAsO2 induced hyperlipidemia, cardiac arsenic content and DNA fragmentation in experimental rats. Histological studies of myocardial tissue supported the protective activity of the AECO. The results concluded that the treatment with AECO prior to arsenic intoxication has significant protecting effect against arsenic-induced myocardial injury.