66 research outputs found
Head and Neck Squamous-Cell cancer and its association with polymorphic enzymes of xenobiotic metabolism and repair
No full textTobacco smoking, alcohol drinking, and occupational exposures to polycyclic aromatic hydrocarbons are the major proven risk factors for human head and neck squamous-cell cancer ( HNSCC). Major research focus on gene-environment interactions concerning HNSCC has been on genes encoding enzymes of metabolism for tobacco smoke constituents and repair enzymes. To investigate the role of genetically determined individual predispositions in enzymes of xenobiotic metabolism and in repair enzymes under the exogenous risk factor tobacco smoke in the carcinogenesis of HNSCC, we conducted a case-control study on 312 cases and 300 noncancer controls. We focused on the impact of 22 sequence variations in CYP1A1, CYP1B1, CYP2E1, ERCC2/XPD, GSTM1, GSTP1, GSTT1, NAT2, NQO1, and XRCC1. To assess relevant main and interactive effects of polymorphic genes on the susceptibility to HNSCC we used statistical models such as logic regression and a Bayesian version of logic regression. In subgroup analysis of nonsmokers, main effects in ERCC2 ( Lys751Gln) C/C genotype and combined ERCC2 ( Arg156Arg) C/A and A/A genotypes were predominant. When stratifying for smokers, the data revealed main effects on combined CYP1B1 ( Leu432Val) C/G and G/G genotypes, followed by CYP1B1 ( Leu432Val) G/G genotype and CYP2E1 ( -70G>T) G/T genotype. When fitting logistic regression models including relevant main effects and interactions in smokers, we found relevant associations of CYP1B1 ( Leu432Val) C/G genotype and CYP2E1 ( -70G>T) G/T genotype ( OR, 10.84; 95% CI, 1.64-71.53) as well as CYP1B1 ( Leu432Val) G/G genotype and GSTM1 null/null genotype ( OR, 11.79; 95% CI, 2.18-63.77) with HNSCC. The findings underline the relevance of genotypes of polymorphic CYP1B1 combined with exposures to tobacco smoke
Spray droplet size, drift potential, and risks to nontarget organisms from aerially applied glyphosate for coca control in Colombia
No full textA wind tunnel atomization study was conducted to measure the emission droplet size spectra for water and Glyphos (a glyphosate formulation sold in Colombia) + Cosmo-flux sprays for aerial application to control coca and poppy crops in Colombia. The droplet size spectra were measured in a wind tunnel for an Accu-Flo nozzle (with 16 size 0.085 [2.16 mm] orifices), under appropriate simulated aircraft speeds (up to 333 km/h), using a laser diffraction instrument covering a dynamic size range for droplets of 0.5 to 3,500 m. The spray drift potential of the glyphosate was modeled using the AGDISP spray application and drift model, using input parameters representative of those occurring in Colombia for typical aerial application operations. The droplet size spectra for tank mixes containing glyphosate and Cosmo-Flux were considerably finer than water and became finer with higher aircraft speeds. The tank mix with 44% glyphosate had a Dv0.5 of 128 m, while the value at the 4.9% glyphosate rate was 140 m. These are classified as very fine to fine sprays. Despite being relatively fine, modeling showed that the droplets would not evaporate as rapidly as most similarly sized agricultural sprays because the nonvolatile proportion of the tank mix (active and inert adjuvant ingredients) was large. Thus, longer range drift is small and most drift that does occur will deposit relatively close to the application area. Drift will only occur downwind and, with winds of velocity less than the modeled maximum of 9 km/h, the drift distance would be substantially reduced. Spray drift potential might be additionally reduced through various practices such as the selection of nozzles, tank mix adjuvants, aircraft speeds, and spray pressures that would produce coarser sprays. Species sensitivity distributions to glyphosate were constructed for plants and amphibians. Based on modeled drift and 5th centile concentrations, appropriate no-spray buffer zones (distance from the end of the spray boom as recorded electronically 5%) for protection of sensitive plants were 50-120 m for coca spray scenarios and considerably lower for poppy spray scenarios. The equivalent buffer zone for amphibia was 5 m. The low toxicity of glyphosate to humans suggests that these aerial applications are not a concern for human health
Public health risks from heavy metals and metalloids present in traditional Chinese medicines
No full textOut of 247 traditional Chinese medicines (TCM) investigated, a proportion were contaminated with arsenic (5-15%), lead (similar to 5%), and mercury (similar to 65%). Some preparations exceeded the tolerable daily intake (TDI) for males and females for arsenic (4 and 5 products, respectively), lead (1 and 2 products), and mercury (5 and 7 products). These exceedances were as high as 2760-fold, which posed a potential danger to public health. As many users are known to self-prescribe, there is a substantial risk of poisoning from the consumption of these contaminated TCM
Toxicology in Australia: A key component of environmental health
No full textManaging public concerns relating to chemical exposures can consume substantial public health resources, particularly as the scientific basis around these issues is often contentious. Toxicology remains underrecognized as a public health discipline in Australia, although Australian toxicologists are making significant contributions from academia, government, and the commercial sector toward assessing the level of risk and protecting the community from environmental hazards. Internationally, the growth of environmental toxicology and the promotion of sound science in risk assessment as a basis for making regulatory decisions have been, to some extent, driven by the outcomes of the 1992 UNCED Conference on Sustainable Development (Rio Summit) and its Chapter 19 Agenda 21 activities. The promotion of safe chemical management practices and the need for global strengthening of capabilities in toxicology are among the initiatives of the Intergovernmental Forum on Chemical Safety (IFCS), which was formed after the Rio Summit to manage these programs. This article describes some of the initiatives in capacity building that marked the development of environmental toxicology in Australia since 1992 in response to these international environmental health initiatives
Environmental Toxicology and Human Health
No full textHumans and animals may be exposed on a continuous daily basis to a mixture of environmental contaminants that may cause adverse consequences. This Topic focuses on environmental pollutants including heavy metals, pesticides, nanoparticles, micro-nanoplastics, indoor air pollutants, pharmaceuticals, and industrial toxicants with effects on human health, risk assessment, and the relationship between various diseases and environmental pollutants. The aim of this Topic is to present a comprehensive overview of various studies carried out with in vivo and in vitro model organisms and the potential risks posed by environmental pollutants to human health. In this Topic, 20 original articles, 6 reviews and 1 communication are collected, with a particular focus on alcohol-based hand sanitizers, polycyclic aromatic hydrocarbons, monochromatic light pollution, paraben as an endocrine disruptor, heavy metal pollution attributed to the antimony and arsenic found in mines in soil, water, and sediments, groundwater with high fluoride levels, the transmission of viruses due to the heating, ventilation, and air conditioning systems of urban subways, chronic home radon exposure, organotin compounds, heavy metal pollutants, polypropylene microplastics, ventral body wall defects in chick embryos, microcystin-LR as an aquatic toxin, N-nitroso compounds, methylmercury as a global pollutant, triazine herbicides, persistent organic pollutants, bisphenol A and trace metals, autophagy, nano- and micro-sized polystyrene particles, tributyltin as an environmental contaminant, polybrominated diphenyl ethers, and per- and polyfluoroalkyl substances
In Vitro Physiologically Based Extraction Test (PBET) and Bioaccessibility of Arsenic and Lead from Various Mine Waste Materials
No full textIn vivo models show that the bioavailability of soil contaminants varies between site and type of matrix. Studies demonstrated that assuming 100% bioavailability of arsenic (As) and lead (Pb) from soils and mine waste materials overestimates the risk associated with human exposure. In in vitro systems, the simulated bioavailability of a contaminant is referred to as the “bioaccessibility” and is used as an alternative quantitative indicator for in vivo derived bioavailability estimates. The general concept of the in vitro extraction test is to predict the bioavailability of inorganic substances from solid matrices by simulating the gastrointestinal tract (GIT) environment. The aims of this study were to: (1) investigate the bioaccessibility of As and Pb from various mine wastes, including tailings, heap leach, and waste rock, using a physiologically based extraction test (PBET); (2) validate the bioaccessibility values from PBET with in vivo bioavailability values measured using animal models; and (3) correlate PBET results with the bioavailability values measured from alternative in vivo models (rats and cattle, from Bruce, 2004). Significant correlation was observed between bioaccessibility values from PBET, and bioavailability values generated for both rats and cattle, demonstrating the potential to utilize PBET as a relatively inexpensive alternative to in vivo models for bioavailability assessment
Metabolic alterations after exposure of rats to certain chlorinated hydrocarbon insecticides.
No full text
Influence of the autonomic nervous system and cardiac drugs upon myocardial glycogen metabolism.
No full text- …
