Comparative assessment of nanomaterial definitions and safety evaluation considerations.

Nanomaterials continue to bring promising advances to science and technology. In concert have come calls for increased regulatory oversight to ensure their appropriate identification and evaluation, which has led to extensive discussions about nanomaterial definitions. Numerous nanomaterial definitions have been proposed by government, industry, and standards organizations.

Workshop report: strategies for setting occupational exposure limits for engineered nanomaterials.

Occupational exposure limits (OELs) are important tools for managing worker exposures to chemicals; however, hazard data for many engineered nanomaterials (ENMs) are insufficient for deriving OELs by traditional methods. Technical challenges and questions about how best to measure worker exposures to ENMs also pose barriers to implementing OELs. New varieties of ENMs are being developed and introduced into commerce at a rapid pace, further compounding the issue of OEL development for ENMs.

EMG spike time difference based feedback control.

Flight control in insects has been studied extensively; however the underlying neural mechanisms are not fully understood. Output from the central nervous system (CNS) must drive wing phase shifts and flight muscle depressor asymmetries associated with adaptive flight maneuvers. These maneuvers will, in turn, influence the insect's sensory environment, thus closing the feedback loop.

Selective tessellation algorithm for modeling interactions between surgical instruments and tissues.

We present a selective spatial tessellation algorithm that is specifically optimized for instrument-to-tissue and instrument-to-instrument collision detection cases, which are the essential part of interaction modeling in surgery simulation with haptic feedback. Virtual surgeries demand haptic rate collision solutions only when instruments are involved in collisions. Other collision cases can be processed at slower rates.

Activation of mouse and human peroxisome proliferator-activated receptors (PPARs) by phthalate monoesters.

Administration of phthalates is known to cause toxicity and liver cancer in rodents through the activation of peroxisome proliferator-activated receptors (PPARs), and the monoesters appear to be the active metabolites that function as ligands of PPARs. There is evidence that PPARs exhibit significant species differences in response to ligand activation. In this study, the activation of mouse and human PPARalpha, PPARbeta, and PPARgamma by a broad class of phthalate monoesters was investigated using a trans-activation assay, functional analysis of PPARalpha target gene expression, and a PPARgamma-mediated differentiation assay.

Phthalate treatment does not influence levels of IgE or Th2 cytokines in B6C3F1 mice.

Bronchial asthma is mediated, in part, by the immunoregulatory cytokines interleukins 4 and 13 (IL-4 and IL-13). These cytokines stimulate IgE synthesis that in turn is associated with airway hyper-responsiveness. Compounds that stimulate IgE synthesis and elicit bronchial reactivity are generally considered to be respiratory sensitizers.

Reproductive toxicity evaluation of dietary butyl benzyl phthalate (BBP) in rats.

Butyl benzyl phthalate (BBP) was administered in the diet at 0, 750, 3750, and 11,250 ppm ad libitum to 30 rats per sex per dose for two offspring generations, one litter/breeding pair/generation, through weaning of F2 litters. Adult F0 systemic toxicity and adult F1 systemic and reproductive toxicity were present at 11,250 ppm (750 mg/kg per day). At 11,250 ppm, there were reduced F1 and F2 male anogenital distance (AGD) and body weights/litter during lactation, delayed acquisition of puberty in F1 males and females, retention of nipples and areolae in F1 and F2 males, and male reproductive system malformations.

NTP center for the evaluation of risks to human reproduction reports on phthalates: addressing the data gaps.

Between 1998 and 2000 an Expert Panel convened by the National Toxicology Program's Center for the Evaluation of Risks to Human Reproduction (NTP-CERHR) reviewed information related to the developmental and reproductive toxicity of seven phthalate esters; DBP, BBP, DnHP, DEHP, DnOP, DINP, and DIDP. Information on exposures was also considered. The objectives were to determine whether any of these phthalates posed potential human reproductive risks, and if so, to define the circumstances.

Tumor induction in mouse liver: di-isononyl phthalate acts via peroxisome proliferation.

Recently several chronic toxicity/carcinogenicity studies of di-isononyl phthalate (DINP) have been reported. These studies defined effect levels for liver tumors in male and female F344 rats at dietary levels exceeding 700 mg/kg/day; the no effect levels were 359 mg/kg/day in males and 442 mg/kg/day in females. Similar results were found in male B6C3F1 mice, but in female mice a significant increase in liver tumors was found at 336 mg/kg/day, making 112 mg/kg/day the NOAEL for liver tumors in that sex and species.

Three-generation reproductive toxicity study of dietary bisphenol A in CD Sprague-Dawley rats.

Bisphenol A (BPA) was evaluated at concentrations of 0, 0.015, 0.3, 4.

Exposure to wood dust and heavy metals in workers using CCA pressure-treated wood.

Chemical pesticide treatment enables relatively nonresistant woods to be used in outdoor construction projects. The most prevalent procedure used to protect these woods is pressure treatment with chromium, copper, and arsenic (CCA). This pilot study examined the airborne concentration and particle size distribution of wood particles, chromium, copper, and arsenic at both outdoor (measured over the whole work day) and indoor (measured during the performance of specific tasks) work sites.

In vitro bioavailability of heavy metals in pressure-treated wood dust.

Pressure treatment with chromium, copper, and arsenic (CCA) is the most prevalent method for protecting wood used in outdoor construction projects. Although these metals are tightly bound to the wood fibers and are not released under most conditions of use, we examined the bioavailability of metals in CCA pressure-treated wood dust in vitro. Cytotoxicity and metallothionein (MT) mRNA expression were examined in V79 Chinese hamster lung fibroblast cells incubated with respirable-size wood dust generated by sanding CCA-treated and untreated (control) Southern yellow pine.

Two-generation reproduction study and immunotoxicity screen in rats dosed with phenol via the drinking water.

This study evaluated the potential reproductive toxicity of phenol in a rat two-generation reproduction study, which included additional study endpoints, such as sperm count and motility, developmental landmarks, histological evaluation of suspect target organs (liver, kidneys, spleen, and thymus), weanling reproductive organ weights, and an immunotoxicity screening plaque assay. Phenol was administered to 30 Sprague-Dawley rats/sex/group in the drinking water at concentrations of 0, 200, 1000, or 5000 ppm. Parental (P1) animals were treated for 10 weeks prior to mating, during mating, gestation, lactation, and until sacrifice.

Two-week (ten-day) inhalation toxicity and two-week recovery study of phenol vapor in the rat.

The toxicity of phenol vapor was evaluated in male and female Fischer 344 rats (20/sex/group) via flow-past nose-only inhalation exposure. The test animals were exposed to target concentrations of 0 (air control), 0.5, 5.

Normal reproductive organ development in Wistar rats exposed to bisphenol A in the drinking water.

Bisphenol A (BPA) is a chemical used primarily as a monomer in the manufacture of numerous chemical products, such as epoxy resins and polycarbonate. The objective of this study was to evaluate potential effects of BPA on sexual development of male rats and was designed to clarify low-dose observations reported as preliminary results by Sharpe et al. (1996).

Normal reproductive organ development in CF-1 mice following prenatal exposure to bisphenol A.

Bisphenol A (BPA) is a monomer used in the manufacture of a multitude of chemical products, including epoxy resins and polycarbonate. The objective of this study was to evaluate the effects of BPA on male sexual development. This study, performed in CF-1 mice, was limited to the measurement of sex-organ weights, daily sperm production (DSP), epididymal sperm count, and testis histopathology in the offspring of female mice exposed to low doses of BPA (0, 0.

Chronic toxicity and three-generation reproduction study of styrene monomer in the drinking water of rats.

Chronic toxicity and reproductive performance were evaluated in groups of rats receiving styrene monomer in their drinking water at nominal concentrations of 0, 125, or 250 ppm. Fifty male and 70 female rats in each test group and 76 males and 104 females in the control group were placed on a 2-year study and followed for observations of general health which included measurement of body weight, food and water consumption, hemograms, clinical chemistries, urinalysis, and histopathological examination. Ten males and 20 females from each group in the study were mated to produce F1 pups.

Toxicology of poinsettia.

1. The acute oral LD50 of poinsettia in Sprague Dawley rats were greater than 25 gm/kg for all plant parts tested. 2.