Pulmonary function changes in rats after chronic and subchronic inhalation exposure to various particulate matter

Acute Toxicity Studies of Xerox Reprographic Toners

Typical reprographic toners consist of a thermoplastic polymer or polymers as the major component, a colorant or colorants (carbon black or color pigments), and small quantities of additives such as charge control and/or lubricating/release agents. Another type of toner contains iron oxides and polymers) as the major components. As a complement to the recently published Xerox chronic inhalation studies of toners, we are reporting the acute toxicity studies of some typical Xerox toners. The studies include acute oral toxicity in rats, acute dermal toxicity in rabbits, acute inhalation toxicity in rats, eye irritation in rabbits, skin irritation in rabbits, skin sensitization in guinea pigs, and the repeated-insult patch test in humans. These studies represent our acute toxicity testing using different protocols with various toners carried out during the period 1969–1984. In addition, we recently carried out acute dermal toxicity testing at 5 g/kg with two representative toners, for the purpose of classification of waste toners in the State of California. The test results consistently indicate that all toners were practically nontoxic: oral LD50 from <5 to <35 g/kg; dermal LD50 from <2 to <5 g/kg; and inhalation LC50 (4 h) from <0.17 to <10.2 g/m3. They were nonirritating to the eye and nonirritating/ nonsensitizing to the skin.

Toxicological Studies of a Representative Xerox Reprographic Toner

Typical Xerox reprographic toners consist of a thermoplastic polymer as the major component, a colorant (carbon black or color pigment), and low quantities of additives such as charge control and/or lubricating agents. Another type of Xerox toner contains iron oxides and a polymer as the major components. Among all toners marketed by Xerox Corporation, the original 1075 toner (being discontinued and reformulated) was a major safety concern, because it contained approximately 2% cetylpyridinium chloride (CPC) as a charge control agent. CPC by itself is very toxic and causes severe irritation to the eye and skin. Although CPC has been used in very low concentrations in consumer products such as mouthwash, it was unknown whether a 50-fold dilution of CPC in the toner formulation would represent any safety issue. Therefore, a series of toxicological testing on the original 1075 toner was conducted. The test results indicate that the original Xerox 1075 toner was practically nontoxic following acute oral, dermal, and inhalation exposures; nonirritating to the eye; nonir-ritating/nonsensitizing to the skin; nonmutagenic in a battery of short-term assays (Ames Salmnonella/microsome assay, mouse lym-phoma assay, in vitro sister chromatid exchange assay in Chinese hamster ovarian cells, and in vitro BALB/3T3 cell transformation assay); and nonteratogenic in rats when inhaling the toner dust up to 1.2 g/m3. In addition, no mutagenic responses were observed from testing the urine or feces (by Ames test) and bone marrow (by examining micronucleus formation) of rats exposed to the toner dust at 1.3 g/m3 at the end of a subchronic inhalation study. Because all Xerox toners are alike, the toxicology of the original Xerox 1075 toner was considered a “worst-case” situation, relative to health and safety. However, it did not appear to represent any health and safety issue. The results of this study, together with the fact that no evidence of carcinogenicity was found in the Xerox chronic inhalation study on toner, indicate that Xerox toners are not safety hazards, with respect to the end points indicated in this report.

Toxicological evaluation of realistic emission source aerosols (TERESA)--power plant studies: assessment of breathing pattern

Our approach to study multi-pollutant aerosols isolates a single emissions source, evaluates the toxicity of primary and secondary particles derived from this source, and simulates chemical reactions that occur in the atmosphere after emission. Three U.S. coal-fired power plants utilizing different coals and with different emission controls were evaluated. Secondary organic aerosol (SOA) derived from α-pinene and/or ammonia was added in some experiments. Male Sprague-Dawley rats were exposed for 6 h to filtered air or different atmospheric mixtures. Scenarios studied at each plant included the following: primary particles (P); secondary (oxidized) particles (PO); oxidized particles + SOA (POS); and oxidized and neutralized particles + SOA (PONS); additional control scenarios were also studied. Continuous respiratory data were obtained during exposures using whole body plethysmography chambers. Of the 12 respiratory outcomes assessed, each had statistically significant changes at some plant and with some of the 4 scenarios. The most robust outcomes were found with exposure to the PO scenario (increased respiratory frequency with decreases in inspiratory and expiratory time); and the PONS scenario (decreased peak expiratory flow and expiratory flow at 50%). PONS findings were most strongly associated with ammonium, neutralized sulfate, and elemental carbon (EC) in univariate analyses, but only with EC in multivariate analyses. Control scenario O (oxidized without primary particles) had similar changes to PO. Adjusted R(2) analyses showed that scenario was a better predictor of respiratory responses than individual components, suggesting that the complex atmospheric mixture was responsible for respiratory effects.

Acute toxicity of nano- and micro-scale zinc powder in healthy adult mice

The purpose of this study is to evaluate the acute toxicity of oral exposure to nanoscale zinc powder in mice. The healthy adult male and female mice were gastro-intestinally administered at a dose of 5 g/kg body weight with two size particles, nanoscale zinc (N-Zn) and microscale zinc (M-Zn) powder, while one group mice treated with sodium carboxy methyl cellulose was used as the control. The symptoms and mortality after zinc powder treatment were recorded. The effects of particles on the blood-element, the serum biochemical level and the blood coagulation were studied after 2 weeks of administration. The organs were collected for histopathological examination. The N-Zn treated mice showed more severe symptoms of lethargy, vomiting and diarrhea in the beginning days than the M-Zn mice. Deaths of two mice occurred in the N-Zn group after the first week of treatment. The mortalities were confirmed by intestinal obstruction of the nanoscale zinc aggregation. The biochemical liver function tests of serum showed significantly elevated ALT, AST, ALP, and LDH in the M-Zn mice and ALT, ALP, and LDH in the N-Zn mice compared with the controls (P<0.05), which indicated that the liver damage was probably induced by both micro- and nano-scale zinc powders. The clinical changes were observed in the two treated group mice as well. The levels of the above enzymes were generally higher in the M-Zn mice than in the N-Zn mice, which implied that M-Zn powder could induce more severe liver damage than N-Zn. The biochemical renal function tests of serum BUN and CR in the M-Zn mice markedly increased either compared with the N-Zn mice or with the controls (P<0.05), but no significant difference was found between the N-Zn and the control mice. However, severe renal lesions were found by the renal histopathological examination in the N-Zn exposed mice. Therefore, we concluded that severe renal damage could occur in the N-Zn treated mice, though no significant change of blood biochemical levels occurred. Blood-element test showed that in the N-Zn mice, PLT and RDW-CV significantly increased, and HGB and HCT significantly decreased compared to the controls, which indicated that N-Zn powder could cause severe anemia. Besides the pathological lesions in the liver, renal, and heart tissue, only slight stomach and intestinal inflammation was found in all the zinc treated mice, without significant pathological changes in other organs.

Nanoparticles - known and unknown health risks

Manmade nanoparticles range from the well-established multi-ton production of carbon black and fumed silica for applications in plastic fillers and car tyres to microgram quantities of fluorescent quantum dots used as markers in biological imaging. As nano-sciences are experiencing massive investment worldwide, there will be a further rise in consumer products relying on nanotechnology. While benefits of nanotechnology are widely publicised, the discussion of the potential effects of their widespread use in the consumer and industrial products are just beginning to emerge. This review provides comprehensive analysis of data available on health effects of nanomaterials.

Type A natriuretic peptides exhibit different bronchoprotective effects in rats

The protective effect of 11.4, 22.8 or 45.6 pmol/kg/min cardiodilatin/atrial natriuretic peptide (CDD/ANP-(99-126)), urodilatin (CDD/ANP-(95-126)) or vehicle intravenously against acetylcholine-induced bronchoconstriction was compared in spontaneously breathing, halothane-anesthetized Wistar rats. The inhalation of acetylcholine induced significant alterations of the spontaneous breathing parameters evaluated by whole-body plethysmography without significant differences between the treatment groups. Forced parameters detect airflow changes with a greater sensitivity and were measured in hyperventilation-induced temporary apnoea after the challenge. The forced expiratory volume in 0.1 s revealed a significant protective effect of 11.4 pmol/kg/min urodilatin compared to the controls whereas the parameters of the forced expiratory flow-volume curve were significantly preserved by 11.4 and 22.8 pmol/kg/min urodilatin (P < 0.05). Urodilatin showed protective effects against an acetylcholine challenge whereas CDD/ANP-(99-126) was without significant influence.

Comparative investigation of the effects of zardaverine and theophylline on pulmonary function in rats

Zardaverine (Byk Gulden, Konstanz, Germany) is a new selective phosphodiesterase (PDE) III/IV inhibitor. The bronchodilating and bronchoprotective potency of zardaverine and the nonselective PDE inhibitor theophylline was compared by measuring typical spontaneous and forced respiratory function parameters in anesthetized female Wistar rats using whole-body plethysmography. Zardaverine (3, 10, 30 mumol/kg) and theophylline (30, 100, 300 mumol/kg), respectively, were given orally in 4% Methocel/0.9% saline solution 20 min before measurement. One week before treatment, control measurements were performed in the same animals after administration of the vehicle. When spontaneously breathing, the 30 mumol/kg zardaverine- (300 mumol/kg theophylline-) treated animals showed significant changes: a 23% (14% ns) decrease in lung resistance and a 43% (25%) increase in dynamic compliance. These changes can be interpreted as an indication of bronchodilation, since quasistatic lung compliance was unchanged. In the acetylcholine challenge test, treatment with only 10 mumol/kg zardaverine (but 300 mumol/kg theophylline) revealed significant changes compared to control measurement: a 37% (28%) lower resistance and 85% (44%) higher compliance. It has been determined that zardaverine is more than 30 times as potent as theophylline in inhibiting acetylcholine-induced bronchospasms, which is also supported by forced expiratory flow data.