Chemical and physical characteristics of cellulose insulation particulates, and evaluation of potential acute pulmonary toxicity

National Institute of Environmental Health Sciences and the National Toxicology Program, Research Triangle Park, North Carolina 27709, USA.
American Journal of Industrial Medicine (Impact Factor: 1.74). 12/2004; 46(6):554-69. DOI: 10.1002/ajim.20101
Source: PubMed


During installation of cellulose insulation (CI) in new and older houses, significant quantities of airborne material are generated. This study characterized the chemical and physical properties, and potential acute pulmonary toxicity of CI.
CI from four manufacturers was analyzed for inorganic additives and trace element impurities. Aerosols were generated and size fractionated. The number and size of fibrous and nonfibrous particles in the respirable fractions were determined. Respirable CI particulates were intratracheally instilled in rats (5 mg/kg) to evaluate potential pulmonary toxicity.
CI samples were similar in composition with small differences due primarily to fire retardants. Less than 0.1% of CI was respirable and contained few fibers. Acute exposure to CI caused transient inflammation in the lungs and increased 4-hydroxyproline. Microscopic evaluation revealed a minimal to mild, non-progressing granulomatous pneumonitis.
Low concentrations of respirable particles were found in CI aerosols. Particles consisted primarily of fire retardants with few fibers, and caused mild pulmonary toxicity in rats.

21 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: An acute study of boron trifluoride (BF3) in rats indicated the 4-hr LC50 to be 1.21 mg/liter. In a 2-week study, all animals exposed to 180 mg/m3 died prior to the sixth exposure, rats exposed at concentrations of 66 and 24 mg/m3 showed clinical signs of respiratory irritation, body weight gain depressions, increased lung weights, and depressed liver weights. Histopathology showed necrosis and pyknosis of the proximal tubular epithelium of the kidneys. This effect was limited to the high-concentration exposure group. Based on the results of these studies, Fischer 344 rats were exposed 6 hr/day, 5 days/week for 13 weeks to a respirable, liquid aerosol of BF3 at concentrations of 0, 2.0, 6.0, and 17 mg/m3. One rat in the high exposure group died. The most significant finding in this group was necrosis of the proximal tubular epithelium of the kidneys. Other observations noted during the study included dried material around the nose and mouth, rales and excessive lacrimation, reversible depression of serum total protein and globulin concentrations, and increases in urinary, serum, and bone fluoride amounts. In the lower exposure groups, findings of respiratory irritation were minimal. All observations occurred in a dose-related pattern. Based on this study, exposure to BF3 at 17 mg/m3 resulted in renal toxicity, while exposure at 6 mg/m3, although showing elevations of fluoride amounts, did not result in a toxic response.
    Toxicology and Applied Pharmacology 04/1986; 83(1):69-78. DOI:10.1016/0041-008X(86)90323-6 · 3.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study examined work-related chronic abnormality in pulmonary function and work-related acute irritant symptoms associated with exposure to borate dust in mining and processing operations. Chronic effects were examined by pulmonary function at the beginning and end of a 7-year interval. Time-specific estimates of sodium borate particulate exposures were used to estimate cumulative exposure during the study interval. Change in pulmonary function over the 7 years was found unrelated to the estimate of cumulative exposure during that interval. Exposure-response associations also were examined with respect to short-term peak exposures and incidence of five symptoms of acute respiratory irritation. Hourly measures of health outcome and continuous measures of particulate exposure were made on each subject throughout the day. Whenever a subject reported one of the irritant symptoms, a symptom intensity score was also recorded along with the approximate time of onset. The findings indicated that exposure-response relationships were present for each of the specific symptoms at several symptom intensity levels. The associations were present when exposure was estimated by both day-long and short-term (15-min) time-weighted average exposures. Associations persisted after taking account of smoking, age, and the presence of a common cold. No significant difference in response rate was found between workers exposed to different types of sodium borate dusts.
    Environmental Health Perspectives 12/1994; 102 Suppl 7(Suppl 7):119-28. DOI:10.2307/3431974 · 7.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Boric acid (BA), an ingredient of many pharmaceutical, cosmetic, and pesticide products, was previously shown to induce reproductive and developmental toxicity in laboratory rodents. In this study, BA (0, 62.5, 125, or 250 mg/kg/day, po) was administered on Gestational Days (GD) 6–19 to New Zealand White rabbits (18–23 pregnant/group). Maternal body weight, food consumption, and clinical condition were monitored at regular intervals throughout gestation. At termination (GD 30), the numbers of uterine implantations, resorptions, dead fetuses, and live fetuses were determined. Fetuses were weighed, and live fetuses examined for external, visceral, and skeletal defects. Maternal food intake decreased during treatment at 250 mg/kg/day and increased at ≥125 mg/kg/day after treatment. Maternal body weight (GD 9–30), weight gain during treatment, gravid uterine weight, and number of ovarian corpora lutea decreased at 250 mg/kg/day. In contrast, maternal corrected gestational weight gain increased at ≥125 mg/kg/day. Maternal liver weight was not affected. Relative (but not absolute) maternal kidney weight increased at 250 mg/kg/day, and microscopic evaluation revealed no treatment-related renal pathology. At 250 mg/kg/day, prenatal mortality was increased (90% resorptions/litter vs 6% for controls), the proportion of pregnant females with no live fetuses was increased (73% vs 0%), and live litter size was reduced (2.3 fetuses/litter vs 8.8). As a result, there were only 14 live fetuses (6 live litters) available for evaluation in the high-dose group, compared to 153–175 live fetuses (18–23 live litters) in the other groups. The percentage malformed fetuses/litter was increased at 250 mg/kg/day, primarily due to cardiovascular defects in 72% of high-dose fetuses vs 3% of controls. The most prevalent cardiovascular malformation (in terventricular septal defect) was observed in 57% of high-dose fetuses compared to 0.6% among controls. At 250 mg/kg/day, average fetal body weight/litter was 92% of the average control weight (not statistically significant). In summary, no definitive maternal or developmental toxicity was observed at 62.5 or 125 mg/kg/day BA. Mild maternal effects and severe developmental toxicity were observed at 250 mg/kg/day.
    Fundamental and Applied Toxicology 12/1996; 34(2). DOI:10.1093/toxsci/34.2.176
Show more