Subchronic and developmental toxicity of aromatic extracts.

Aromatic extracts (AEs; distillate AEs [DAEs] and residual AEs [RAEs]) are complex, highly viscous liquid petroleum streams with variable compositions derived by extraction of aromatic compounds from distillate and residual petroleum fractions from a vacuum distillation tower, respectively. The DAEs generally contain significant amounts of polycyclic aromatic compounds (PACs) and are carcinogenic. The RAEs typically contain lower concentrations of biologically active PACs.

Acute, subchronic, and developmental toxicological properties of lubricating oil base stocks.

Lubricating oil base stocks (LOBs) are substances used in the manufacture of finished lubricants and greases. They are produced from residue remaining after atmospheric distillation of crude oil that is subsequently fractionated by vacuum distillation and additional refining steps. Initial LOB streams that have been produced by vacuum distillation but not further refined may contain polycyclic aromatic compounds (PACs) and may present carcinogenic hazards.

A consistent and transparent approach for calculation of Derived No-Effect Levels (DNELs) for petroleum substances.

The REACH legislation introduced Derived No-Effect Levels (DNELs) which are defined as 'the levels of exposure above which humans should not be exposed'. DNELs were required for several categories of petroleum substances and CONCAWE developed a consistent approach for their derivation. First, the No-Observed Effect Level from a relevant study was corrected for pattern and route of exposure to obtain a modified Point-of-Departure (POD(modified)).

Respiratory toxicology of mineral oils in laboratory animals.

Early subchronic and chronic inhalation toxicology studies on various petroleum mineral oils and formulated lubricants supported the ACGIH TLV of 5 mg/m(3) for mineral oil mist. Additional subchronic studies with aerosolized mineral base oils and lubricants during the last 15 years demonstrated that exposures to aerosols of mineral base oils (often >100 mg/m(3)) resulted mainly in concentration-related accumulation in the lung of alveolar macrophages laden with oil droplets. Inflammatory cells were observed with higher aerosol concentrations, consistent with the clinical literature from highly exposed workers.

Subchronic inhalation exposures to aerosols of three petroleum lubricants.

Subchronic inhalation studies were performed with three petroleum lubricants: generic cutting oil (GCO), generic gear oil (GO), and generic commercial engine oil (CEO). Each formulation had a mineral oil base. Sprague-Dawley rats were exposed 6 hours/day, 5 days/week for 13 weeks to aerosol concentrations of 0 (untreated controls), 0 (sham-exposed controls), approximately 50, 150, or 400-520 mg/m3.

Comparison of synthetic zeolite catalysts and alumina binders administered intratracheally to rats.

An intratracheal (IT) screening assay was performed in rats on a series of aluminosilicate catalysts (synthetic zeolites) and alumina binders to compare their relative ability to cause pulmonary fibrosis and related changes. Before initiation of IT screens, both the uniformity of deposition and residence time of a prototype catalyst in the lung were determined. Subsequently, the test materials were instilled and animals were evaluated 6 mo later for lung volumes, pulmonary pressure-volume curves, pulmonary hydroxyproline (OHPro) content, lung weights, and histopathology.

Short-term exposures of rats to airborne hydrogen fluoride.

A series of acute inhalation exposures was performed with airborne hydrogen fluoride (HF) to establish the concentration response for nonlethal effects in the rat. Exposures were either 2 or 10 min long; concentrations ranged from 135 to 8621 ppm. Three additional exposures (20 to 48 ppm) were performed for 60 min.

Acute effects of 10-minute exposure to hydrogen fluoride in rats and derivation of a short-term exposure limit for humans.

A series of acute inhalation exposures of female rats was conducted with hydrogen fluoride (HF) to establish a concentration-response curve for nonlethal exposures. Durations of 2 and 10 min were used to simulate possible short-term exposures. Concentrations of HF ranged from 593 to 8621 ppm for 2-min exposures and from 135 to 1764 ppm for 10-min exposures.

Use of a surrogate aerosol in a preliminary screening for the potential carcinogenicity of coal coated with No. 6 fuel oil.

Coal, which contains significant amounts of water, can be ground and dried to produce an efficient fuel for electric power plants; however, spontaneous combustion can occur in the dried coal. Liquid petroleum hydrocarbons inhibit this combustion, but not all petroleum streams are effective. No.

Toxicity evaluation of petroleum blending streams: reproductive and developmental effects of a distillate from light alkylate naphtha.

A distillate of light alkylate naphtha (CAS number 64741-66-8; LAN distillate) was administered via inhalation, 6 h/d, 7 d/wk to 4 groups of Sprague-Dawley rats (10/sex/dose) at target concentrations of 0 (filtered air control), 5, 12.5, or 25 g/m3 with the highest dose exceeding 60% of the lower explosive limit of LAND. Exposure began 2 wk prior to mating and continued throughout gestation until postnatal d 4 for females or for 8 consecutive weeks for males.

Subchronic and developmental toxicity studies of vaporized diisopropyl ether in rats.

Two inhalation studies were performed with a vaporized sample of commercial-grade diisopropyl ether (DIPE). In the subchronic study, Sprague-Dawley rats (14/sex) were exposed to 0 (both untreated and sham-exposed controls), 480, 3300, or 7100 ppm DIPE for 6 h/d, 5 d/wk, for approximately 90 d. DIPE itself accounted for 91-95% of the vapors, with the remainder being a mixture of 27-29 compounds.

Cell proliferation in rat forestomach following oral administration of styrene oxide.

A series of range-finding studies was conducted in a limited number of male F344 rats on the relation between cell proliferation and styrene oxide (SO) given as gavage doses in corn oil ranging from 550 to 1500 mg SO/kg. In each study, rats were injected with [3H]thymidine (0.50 mCi/g, ip) at intervals from 1 to 48 hr after dosing with SO.

Light catalytically cracked naphtha: subchronic toxicity of vapors in rats and mice and developmental toxicity screen in rats.

Both a subchronic inhalation study and a developmental toxicity screen were performed with vapors of light catalytically cracked naphtha (LCCN). In the subchronic study, four groups of mice and rats (10 animals per sex per species) were exposed for approximately 13 wk (6 h/d, 5 d/wk) to concentrations of LCCN vapors of 0, 530, 2060, or 7690 mg/m3. An untreated control group was also included.

Four-week inhalation exposures of rats to aerosols of three lubricant base oils.

Sprague-Dawley rats were exposed to aerosols of one of three base stocks used to formulate lubricating oils. These stocks were a solvent-refined oil (SRO), a hydrotreated and acid-washed white oil (WTO) and a severely hydrotreated and hydrocracked oil (HBO). Exposures were for 6 h per day, 5 days per week for ca.

Role of exposure parameters in toxicity of aerosolized diesel fuel in the rat.

Sprague-Dawley rats were exposed to aerosolized diesel fuel (ADF) to determine the potential health effects in military troops during exposure to this visual obscurrant. Acute range finding studies were performed to estimate exposure conditions at which minimal (less than 1%) mortality would occur. This information was used in the design of a repeated exposure study to test the relative significance of the frequency of exposures, the duration of exposure, and aerosol concentration in any toxicity which might occur.

A composite model for multiple assays of skin irritation.

A model for skin irritation was developed for simultaneous evaluation of the influence on irritation of abrasion, occlusion, and duration of treatment and for fulfillment of requirements for labeling considerations under DOT, CPSC-FHSA, OSHA, and EEC. This model greatly reduces the number of animals required to address submissions under multiple agencies compared to performing each test separately. In this model, which we have called a Composite Skin Irritation test, a test material is placed on three pairs of intact and abraded sites on each rabbit; one pair of sites is occluded for 4 hours, one for 24 hours, and the other left unoccluded for 24 hours.

Potentiating effects of oxygen in lungs damaged by methylcyclopentadienyl manganese tricarbonyl, cadmium chloride, oleic acid, and antitumor drugs.

The intraperitoneal administration of methylcyclopentadienyl manganese tricarbonyl (MMT) and cyclophosphamide, exposure to an aerosol of cadmium chloride, intravenous administration of oleic acid, and intratracheal instillation of bleomycin to young female BALB/c mice or CD/CR rats result in acute lung injury. Pulmonary morphology and lung collagen content were examined in animals treated with these chemicals alone or in combination with an elevated oxygen concentration (80%) in the inspired air. In mice, the development of fibrosis could be significantly enhanced if animals treated with MMT, cadmium chloride, cyclophosphamide, or bleomycin were exposed to 80% oxygen immediately following exposure to these agents.

Pathogenesis of lesions induced in rat lung by chronic tobacco smoke inhalation.

Lesions were induced in the lungs of specific-pathogen-free F344 rats by chronic tobacco smoke exposure. Animals exposed to 7 cigarettes/day were killed after 1, 1.5, or 2 years of exposure.

Formaldehyde and tumors in hamster respiratory tract.

Male Syrian golden hamsters were exposed to 10 ppm of formaldehyde (H2CO) 5 times/week for lifetime. Survival of the treated animals was reduced relative to unexposed controls. No tumors were observed in histologic sections of respiratory tract tissues from either unexposed or treated animals.

Effect of sulfur dioxide on the morphology and mucin biosynthesis by the rat trachea.

Specific-pathogen-free rats were exposed to 400 ppm sulfur dioxide daily for up to 7 weeks. At intervals during exposure, tracheas were removed and incubated in vitro in culture medium containing radioactive glycoprotein precursors. The most prominent histological changes due to SO2 were progressive hypertrophy and hyperplasia of the submucosal mucous glands accompanied by a flattening of the epithelium with eventual recovery.

Chronic inhalation of cigarette smoke by F344 rats.

Specific-pathogen-free female F344 rats were exposed by inhalation to what was considered a maximal tolerated dose of cigarette smoke. Total pulmonary deposition of smoke particulates from a single cigarette was 0.25 mg in young rats.

A method for rapid scoring of respiratory tumors in hamsters.

The larynx, trachea, and lung of Syrian golden hamsters treated with diethylnitrosamine were stained with modified Wright's stain and rendered semitransparent by a clearing technique. Areas of dense cell aggregation (tumors) were readily observable under a dissecting microscope. Tumor scoring at this subgross level correlated with subsequent microscopic evaluation, except that several tumors were found on the subgross level which would not have been observed during routine histologic procedures.

A tobacco smoke inhalation exposure device for rodents.

A system which utilizes a piston pump to generate cigarette smoke under standard conditions, and expose rodents to the inhalation of diluted smoke for controlled periods of time is described. Variations of the basic system have been employed to exposure groups of ten to twenty hamsters or rats, and should allow exposures of up to forty mice. The system has been in use for approximately 24 months in routine chronic exposures of rats.