Pathologic findings in rats following inhalation of combustion products of polytetrafluoroethylene (PTFE)

A review on occurrence, characteristics, toxicology and treatment of nanoplastic waste in the environment

Nanoplastics (NPs) have showed hotspot of discussion in recent years due to their impact in environment as a futuristic major pollutant in water, soil and air. In this correspondence review on the occurrence of nanoplastics and its effect at the environment as a waste have been overviewed and assimilated. It has the direct or indirect effect on aquatic and terrestrial geographical living beings due to its toxicity. The review revealed the major lacking in the field of analysis, database of contaminant quantity and legislative support to essential eradication on the existing imminent pollutant effects. A brief discussion about properties and characters of nanoplastics has been done. The environment exposed with macroplastics, microplastics and nanoplastics has abundantly contaminated the ecosystem surrounding it. Recent studies reveal that the major health effect by nanosize particles has mainly induced toxicity to the aquatic and terrestrial animals when compared to microsize particles and macrosize particles. The drastic effects and its toxicity in living ecosystem due to nanoplastics have been shown. The occurring waste is supposed to manage from environment by treating before entering into environment. The degradation methods for treatment of nanoplastics have been discussed in this review work.

Pulmonary toxicity following exposure to an aerosolized leather protector

BACKGROUND

An aerosol spray for leather protection was reformulated to remove trichloroethane. The new formulation contained isobutane, n-heptane, ethyl acetate and fluoroaliphatics.

RETROSPECTIVE REVIEW

Thirty-nine patients reported symptoms to the regional poison center. Respiratory symptoms developed within hours of exposure. Most symptoms resolved within two days. Abnormal pulmonary function tests, including obstructive disease or diminished diffusing capacity, were demonstrated in three of the four tested patients.

CONCLUSIONS

The mechanism for the pulmonary toxicity has not been determined.

The effects of exercise following exposure to bis(trifluoromethyl) disulfide

Bis(trifluoromethyl) disulfide (TFD) was originally designed for use as an agricultural fumigant. Inhalation of toxic doses of TFD results in varying degrees of pulmonary edema. The purpose of this study was to determine if exhaustive exercise would potentiate the toxic effects of TFD. One group of treadmill-acclimated rats was exercised to exhaustion following a 10-minute whole-body exposure to TFD. A second group was similarly exposed but not exercised. Two other groups of rats were sham exposed; one was exercised while one remained sedentary following the sham exposure. Twenty-four hours after exposure, the animals were sacrificed; the lungs were removed and weighed, and a portion was collected for histopathologic examination. The remaining lung tissue was allowed to dry to constant weight. There was no difference in endurance times between exposed and sham-exposed rats. There was a significant increase in the amount of pulmonary edema and associated pulmonary pathology in rats exercised following exposure to TFD. Eleven of twelve animals exercised following exposure to TFD and three of twelve animals which remained sedentary following exposure died by 24 hours. The degree of pulmonary pathology in all rats exposed to TFD was profound.

Attenuation of perfluoropolymer fume pulmonary toxicity: effect of filters, combustion method, and aerosol age

Thermal decomposition products of some perfluorinated polymers are toxic to experimental animals in small-scale combustion toxicity tests; the toxicity is dependent upon the heating procedure, combustion temperature, and other experimental conditions. In the current studies we investigated the time course of fume generation and exposure on pulmonary effects in rats following a 30-min exposure to perfluoropolymer decomposition products (i.e., fume concentration = 0.2 mg/m3 of tetrafluoroethylene/hexafluoropropylene copolymer (FEP)) pyrolyzed with either static or dynamic airflows. In the first set of experiments, five different groups of rats were exposed to FEP fumes in a static combustion toxicity test system. Three groups were exposed to unfiltered FEP fumes during 0- to 15-, 15- to 30-, and 0- to 30-min intervals, respectively, and one to a filtered (particle-free) atmosphere of combusted FEP for 30 min. Sham-exposed rats constituted the control group. Immediately after exposure, the rats were sacrificed and their lungs weighed and lavaged or perfused to assess indices of cytotoxicity. Our results showed that lung weights, markers of inflammation, and pulmonary hemorrhage and alkaline phosphatase, beta-glucuronidase, lactate dehydrogenase, and protein levels in bronchoalveolar lavage fluids were significantly elevated in all unfiltered FEP-exposed groups compared to those in either the rates exposed through filters or controls (P less than 0.01). In a second set of experiments using a dynamic pyrolysis toxicity test system, rats were exposed for 30 min to FEP-pyrolyzed fumes which were either freshly generated or aged for 1 or 5 min prior to delivery to the animal's breathing zone. Subsequently, lung cytotoxicity parameters were measured. Rats exposed directly to the fresh fumes demonstrated toxic effects consistent with those described above (P less than 0.01), but the pulmonary toxicity of aged (i.e., 1 or 5 min delay) FEP fumes was diminished in a time-dependent manner, suggesting that the toxicant was unstable. Histopathological studies correlated with biochemical results and revealed that inhalation of unfiltered or freshly generated FEP fumes produced a severe lung injury characterized by the development of alveolar and interstitial edema, intraalveolar hemorrhage, congestion, and fibrin deposition. Electron microscopy studies demonstrated severe damage to terminal bronchiolar cells and detachment of Type I epithelial and endothelial cells in pulmonary regions. The severity of pathology observed in lungs of rats exposed to 1-min aged fumes was intermediate between unfiltered/unaltered fume-exposed animals and sham controls. The results of these studies demonstrate that the lung toxicity of perfluoropolymer fumes is associated with the aerosol phase generated in perfluoropolymer pyrolysis.

Formation of acute pulmonary toxicants following thermal degradation of perfluorinated polymers: evidence for a critical atmospheric reaction

In some small-scale tests of combustion-product toxicity, perfluorinated polymers (FP) have been shown to be much more toxic than other common materials. These studies were conducted to determine the conditions under which highly toxic decomposition products of FP are formed. A modification of the National Bureau of Standards exposure system (Levin et al. National Bureau of Standards 1982, NBS IR 82-2532) was used, in which materials could be heated either in a cup furnace or above a small methane flame. At 700 degrees C, the approximate lethal concentrations (ALCs) of the products formed from polytetrafluoroethylene (pTFE) and from hexafluoropropylene/tetrafluoroethylene copolymer (FEP) in the CH4 flame (applied for 1 min) are approximately 850 times higher than the ALCs of the products formed in the cup furnace. Analytically, the major products formed initially from pTFE at 700 degrees C under either condition (flame or cup furnace) are similar but they disappear rapidly in the presence of continuous heat. When the cup furnace is removed 1 min after pTFE is added (a procedure temporally similar to the use of the flame) the toxicity of the products is again low. However, when heat from either the cup furnace or from a small secondary flame is applied continuously (for up to 30 min) to the initial products formed from pTFE in the flame, high toxicity is observed. These observations are supported by pathological evaluation of the respiratory tracts of exposed rats. Thus, the inhalation toxicity of FP thermal decomposition products is related to a heat- and time-dependent atmospheric reaction. Such mechanisms should be considered in estimating the fire hazard of these materials in use.