Stachybotrys chartarum, also known as "black mold," is a cellulolytic saprophyte with a worldwide distribution. Public concern for potential illnesses associated with water-damaged indoor environments has been heightened since the report of pediatric acute idiopathic pulmonary hemorrhage/hemosiderosis cases in the United States and following recent natural disasters. Although mycotoxicosis and pulmonary immunological endpoints have been previously examined, the systemic toxicity following subchronic inhalation of viable S. chartarum remains undercharacterized. To evaluate the toxicological responses to S. chartarum, B6C3F1/N mice were exposed to viable S. chartarum conidia (spores) twice a week for 3 months. All in-life procedures, including inhalation exposure, test article preparation, and hematology analysis, were completed by the National Institute for Occupational Safety and Health (NIOSH, Morgantown, WV). Battelle (Columbus, OH) conducted terminal necropsies, measured terminal body and organ weights, and evaluated gross lesions onsite at the NIOSH facility. Tissue processing and histopathology were completed at Battelle. Genetic toxicology studies on mouse peripheral blood erythrocytes were conducted by Integrated Laboratory Systems, LLC (Research Triangle Park, NC). (Abstract Abridged).
Acetoin and 2,3-pentanedione are highly volatile components of artificial butter flavoring (ABF). Concerns over the inhalation toxicity of these compounds originate from the association between occupational exposures to ABF and adverse fibrotic lung effects, specifically obliterative bronchiolitis (OB) in the distal airways. 2,3-Pentanedione has been used as a replacement for 2,3-butanedione (diacetyl) in some ABF due to concerns about the respiratory toxicity of 2,3-butanedione. However, 2,3-pentanedione is structurally similar to 2,3-butanedione and has been shown to exhibit potency similar to 2,3-butanedione regarding airway toxicity following acute inhalation (whole-body) exposure. This report describes a series of studies to evaluate the 2-week inhalation toxicity of acetoin and the 3-month inhalation toxicity of acetoin and 2,3-pentanedione. (Abstract Abridged).
Oral human exposure to vanadium may occur due to its presence in food and drinking water and its use in dietary supplements. The most prevalent oxidation states of vanadium in food and drinking water have been characterized as tetravalent and pentavalent. Vanadyl sulfate and sodium metavanadate were selected as representative tetravalent (V4+) and pentavalent (V5+) test articles for these studies, respectively. To assess the potential for oral toxicity of vanadium compounds with differing oxidation states under similar test conditions, the 3-month National Toxicology Program (NTP) toxicity studies of sodium metavanadate and vanadyl sulfate were conducted in male and female Sprague Dawley (Hsd:Sprague Dawley SD) rats (including perinatal exposure) and in B6C3F1/N mice. Drinking water concentrations for sodium metavanadate (0, 31.3, 62.5, 125, 250, and 500 mg/L) and vanadyl sulfate (0, 21.0, 41.9, 83.8, 168, and 335 mg/L) were selected on the basis of previously published 14-day drinking water studies conducted as part of the NTP vanadium research program. (Abstract Abridged).
(+)-Usnic acid is a secondary metabolite of lichens belonging to the Usnea genus. Usnea lichens and purified usnic acids have been used historically in traditional herbal medicine as bactericidal and antimicrobial agents. (+)-Usnic acid exhibits membrane proton uncoupling activity, which not only forms the mechanistic basis of its bactericidal action, but also has provided a rationale for its use as a fat-burning, weight-loss agent. Purified (+)-usnic acid has been marketed in the United States for this purpose either alone or in combination with other chemical agents. Use of some of these fat-burning products that contain (+)-usnic acid has resulted in serious liver damage. This study investigated the potential toxicity of (+)-usnic acid in male and female F344/N Nctr rats and B6C3F1/Nctr mice that were exposed via feed for 3 months. F344/N Nctr rats were administered 0, 30, 60, 120, 360, or 720 ppm in feed, while B6C3F1/Nctr mice were administered 0, 15, 30, 60, 180, or 360 ppm in feed. (Abstract Abridged).
Usnea lichens and purified usnic acids have been used historically in traditional herbal medicine as bactericidal and antimicrobial agents. Usnea lichens contain 1%-3% (+/-)-usnic acid and extracts of these lichens are currently marketed in the United States as herbal antimicrobial agents. (+/-)-Usnic acid exhibits membrane proton uncoupling activity, which not only forms the mechanistic basis of its bactericidal action, but also has provided a rationale for its use as a fat burning, weight-loss agent. Purified (+)-usnic acid has been marketed in the United States for this purpose either alone or in combination with other chemical agents. Use of some of these fat burning products that contain (+)-usnic acid has resulted in serious liver damage. This study investigated the potential toxicity of ground Usnea lichens containing (+/-)-usnic acid in male and female Fischer 344/N Nctr rats and B6C3F1/Nctr mice that were exposed via feed for 3 months. F344/N Nctr rats were administered 0, 30, 60, 120, 360, or 720 ppm in feed, while B6C3F1/Nctr mice were administered 0, 15, 30, 60, 180, or 360 ppm in feed. (Abstract Abridged).
