Pulmonary biocompatibility assessment of inhaled single-wall and multiwall carbon nanotubes in BALB/c mice.

With the widespread application of carbon nanotubes (CNTs) in diverse commercial processes, scientists are now concerned about the potential health risk of occupational exposures. In this study, CNT-induced pulmonary toxicity was investigated by exposing BALB/c mice to aerosolized single-wall (SW) CNT and multiwall (MW) CNT (5 µg/g of mice) for 7 consecutive days in a nose-only exposure system. Microscopic studies showed that inhaled CNTs were homogeneously distributed in the mouse lung. The total number of bronchoalveolar lavage polymorphonuclear leukocytes recovered from the mice exposed to SWCNT and MWCNT (1.2 × 10(6) ± 0.52 and 9.87 × 10(5) ± 1.45; respectively) was significantly greater than control mice (5.46 × 10(5) ± 0.78). Rapid development of pulmonary fibrosis in mice that inhaled CNT was also confirmed by significant increases in the collagen level. The lactate dehydrogenase levels were increased nearly 2- and 2.4-fold in mice that inhaled SWCNT and MWCNT, respectively, as compared with control mice. In addition, exposure of CNTs to mice showed a significant (p < 0.05) reduction of antioxidants (glutathione, superoxide dismutase, and catalase) and induction of oxidants (myloperoxidase, oxidative stress, and lipid peroxidation) compared with control. Apoptosis-related proteins such as caspase-3 and -8 activities were also significantly increased in mice that inhaled CNT than in control mice. Together, this study shows that inhaled CNTs induce inflammation, fibrosis, alteration of oxidant and antioxidant levels, and induction of apoptosis-related proteins in the lung tissues to trigger cell death.

An environmental assessment of mold concentrations and potential mycotoxin exposures in the greater Southeast Texas area.

An assessment of indoor air quality in homes from the greater Houston and Southeast Texas area was sampled over a three-month period to ascertain the potential toxic exposure to molds and mycotoxins. In 2001 Houston experienced widespread flooding due to Tropical Storm Allison. The slow receding waters allowed molds to proliferate to great levels and affected many homes and businesses in and around the Houston area. Source (air) and surface (swab, tape, and bulk) samples were taken in fungal contaminated residences to measure the amounts of airborne and surface contaminants. Indoor airborne counts of fungal spores that were identified to be 80% or more of the outside counts of similar fungal genera were classified as indoor air contaminants. This study identified species of Aspergillus, Penicilliulm, and Cladosporium at levels ranging from 80% to 20 times greater than the corresponding outdoor readings in the greater Southeast Texas area. Aspergillus and Penicillium species are considered potentially toxic to humans at elevated levels due to their ability to produce mycotoxins. Cladosporium is considered nonpathogenic, but can still cause allergenic reactions from hyphal fragments. Surface sampling which is utilized for identification of visible mold contaminants, identified species of Aspergillus. Penicillium, Chaetomium, Cladosporium, and Stachybotrys ranging from 1 to 100 total colony counts (1-100% for tape and bulk noncultured assays) contingent upon the extent of visual contamination. The numerical values from surface sampling were used primarily to identify the degree of visual contamination, as well as, identify any molds that may have been too heavy to become aerosolized.