Investigating the relationship between β-carotene intake from diet and supplements, smoking, and lung cancer risk.

β-carotene is a naturally occurring and safe dietary source of vitamin A that is associated with cancer risk reductions when consumed in typical dietary amounts. However, two clinical trials reported increased incidence of lung cancer and total mortality among heavy smokers taking β-carotene supplements (20 or 30 mg/day). Based on these findings, the Joint FAO/WHO Expert Committee on Food Additives withdrew Acceptable Daily Intake values for β-carotene (0-5 mg/kg bw).

Carcinogenicity of Poorly Soluble Low Toxicity Particles: Commentary on Epidemiology as a Risk Assessment "Reality Check".

Inhaled particles that are poorly soluble or insoluble and of low toxicity ("poorly soluble low toxicity" or "PSLT" particles), can accumulate in the lung and at lung overload levels induce lung cancers in rats. The question of whether PSLT particles increase lung cancer risk in humans is complicated by large differences between rats and humans and the relatively large particle doses administered in animal studies even when compared with heavy human occupational exposures. We review the findings of epidemiological studies on occupational exposure to each of three different PSLT particles (carbon black, talc and taconite).

In utero arsenic exposure in mice and early life susceptibility to cancer.

In its review of the U.S. Environmental Protection Agency's toxicological review of inorganic arsenic (iAs), the National Academy of Sciences identified carcinogenic endpoints among the highest priority health effects of concern and stated the need to consider evidence that early life exposures may increase the risk of adverse health effects.

Risk assessment of an essential element: manganese.

Manganese (Mn) is an essential element for humans, animals, and plants and is required for growth, development, and maintenance of health. Mn is present in most tissues of all living organisms and is present naturally in rocks, soil, water, and food. High-dose oral, parenteral, or inhalation exposures are associated with increased tissue Mn levels that may lead to development of adverse neurological, reproductive, or respiratory effects.

State-of-the-science review: Does manganese exposure during welding pose a neurological risk?

Recent studies report that exposure to manganese (Mn), an essential component of welding electrodes and some steels, results in neurotoxicity and/or Parkinson's disease (PD) in welders. This "state-of-the-science" review presents a critical analysis of the published studies that were conducted on a variety of Mn-exposed occupational cohorts during the last 100 yr, as well as the regulatory history of Mn and welding fumes. Welders often perform a variety of different tasks with varying degrees of duration and ventilation, and hence, to accurately assess Mn exposures that occurred in occupational settings, some specific information on the historical work patterns of welders is desirable.

Fate of manganese associated with the inhalation of welding fumes: potential neurological effects.

Welding fumes are a complex mixture composed of different metals. Most welding fumes contain a small percentage of manganese. There is an emerging concern among occupational health officials about the potential neurological effects associated with the exposure to manganese in welding fumes.

Research strategies for safety evaluation of nanomaterials, part IV: risk assessment of nanoparticles.

Nanoparticles are small-scale substances (<100 nm) with unique properties and, thus, complex exposure and health risk implications. This symposium review summarizes recent findings in exposure and toxicity of nanoparticles and their application for assessing human health risks. Characterization of airborne particles indicates that exposures will depend on particle behavior (e.

Mutant p53 is constitutively phosphorylated at Serine 15 in UV-induced mouse skin tumors: involvement of ERK1/2 MAP kinase.

Upon DNA damage, phosphorylation and nuclear translocation of wild-type p53 tumor suppressor protein signals its functional activation. However, very little is known about phosphorylation and localization of mutant p53. We found that mutant p53 protein in UV-induced murine primary skin tumors and cultured cell lines was constitutively phosphorylated at serine 15 residue and localized in the cell's nuclei.