D.D. Mahlum

Comparative chemical composition and biological activity of single- and two-stage coal liquefaction process streams

Abstract Samples from several integrated two-stage coal liquefaction (ITSL) process streams were collected under both normal and off-normal operating conditions. Selected crude materials were tested for their ability to initiate tumorigenicity in the initiation/promotion assay in mouse skin. Crude materials and their chemical class fractions were assayed for microbial mutagenic activity in the standard Ames test with S. typhimurium TA98, and selected samples were also subjected to the Chinese hamster ovary mammalian cell assay for mutagenicity. Mass spectral and gas chromatographic—mass spectral (g.c.—m.s.) analyses were carried out on these materials. Results were compared with those for analogous materials from solvent refined coal (SRC) single stage liquefaction processes. In general, the ITSL distillates were of higher molecular weight, higher hydroaromatic content, lower nitrogen content and were somewhat less alkylated than the analogous SRC materials. Compared to the SRC coal liquefaction materials, the ITSL distillates and bottoms materials collected under normal run conditions were substantially less active in both the microbial and mammalian cell mutagenicity assays. These same materials were also less active than ITSL samples collected under off-normal conditions. G.c.—m.s. analyses showed that ITSL materials collected under normal operating conditions were substantially reduced in amino polycyclic aromatic hydrocarbon content when compared to both the off-normal ITSL, and SRC materials. Activity of the ITSL materials as initiators of tumorigenesis was greater than expected, based on results from the in vitro assays and not significantly different than that of the SRC materials. The higher initial boiling point of the ITSL distillates probably accounts for much of their greater than expected initiating activity compared to the SRC materials.

Effects of inhalation exposure to a high-boiling (288 to 454°C) coal liquid

Abstract Coal liquids have been evaluated in a variety of short-term toxicological assays; however, few studies have been conducted to determine the systemic effects after inhalation exposure to these materials. To extend the data base on potential health effects from coal liquefaction materials, we performed a study with solvent refined coal (SRC)-II heavy distillate (HD). Fischer-344 rats were exposed for 6 hr/day, 5 days/week for 5 or 13 weeks to an aerosol of HD (boiling range, 288 to 454°C) at concentrations of 0.69, 0.14, 0.03, or 0.0 mg/liter of air for the high, middle, low, and control groups, respectively. Survival through 13 weeks of exposure was greater than 90% for all groups; body weights for exposed animals were decreased in a dose-dependent manner. significant increases in liver weights and decreases in thymus and ovary weights were observed for treated animals compared with controls. There were also significant treatment-related decreases in erythrocytes, hemoglobin, volume of packed red blood cells, lymphocytes, eosinophils, and total white blood cells. After 5 weeks of exposure serum cholesterol concentrations increased in a dose-dependent manner for both sexes and serum triglyceride amounts decreased for males but not for females. After 13 weeks of exposure, high-dose animals had significant increases in cholesterol (males only), triglycerides, blood urea nitrogen, and serum glutamic pyruvic transaminase (SGPT; males) and significant decreases in albumin, SGPT (females), and lactate dehydrogenase (LDH). Examination of bone-marrow preparations from exposed animals demonstrated consistent decreases in the degree of cellularity, suggesting that this organ is a target for HD. Microscopic evaluation of organ sections indicated exposure-related changes for nasal mucosa, pulmonary macrophages, thymus, liver, kidney, bone marrow, ovaries, and cecum. Results from this study indicated dose-dependent increases in the severity of the lesions observed, with few effects in the low-exposure group that were attributable to the exposure.

Comparison of fetotoxic effects of a dermally applied complex organic mixture in rats and mice

A high-boiling (288-454 degrees C), coal-derived complex organic mixture (COM) has been shown to be teratogenic in rats following inhalation and oral routes of exposure. To determine whether similar changes also occur after dermal exposure to this COM, pregnant rats and mice were exposed during periods of organogenesis (Days 11 to 15 of gestation). Shaved backs were painted with 0, 500, or 1500 mg/kg of the COM (control, low, or high dose, respectively); the exposed area was not occluded. Maternal weight gain during the gestation period decreased with increasing dose in rats but not in mice. Examination of rat fetuses on Day 20 of gestation showed that resorptions had occurred in more than 90% of low- and high-dose litters (vs 6% in the control group). In mice, fetal examinations on Day 18 of gestation showed that resorptions occurred in 71% of litters from both exposure groups (vs 14% in the controls). Fetal measurements indicated that both the weight and the length of rat fetuses decreased with increasing dose, but mouse fetuses were unaffected. Cleft palates, absent in the control groups, were observed in 50 to 55% of the high-dose group and 5 to 8% of the low-dose fetuses of both species. Small fetal lungs occurred in nearly 100% of the exposed rat fetuses and in 25% of the high-dose mice; the incidence of small lungs was 1% in control animals. Other variations observed in exposed groups included edema and reduced ossification in the rat and renal pelvic cavitation in the mouse.(ABSTRACT TRUNCATED AT 250 WORDS)

Promotion of preneoplastic changes in liver by coal-derived organic mixtures applied to skin

The promotion of preneoplastic hepatocyte foci was observed in rats neonatally initiated by a single intraperitoneal injection of benzo[a]pyrene (BP) or diethylnitrosamine (DEN) and exposed, from weaning, to repeated topical applications of coal-derived complex organic mixtures that are carcinogenic for mouse skin. Topical application of these mixtures in the absence of prior initiation did not cause significant induction of hepatocyte foci. These observations indicate the advantage of the neonatal rat hepatocarcinogenesis system for detecting promoting activity in carcinogenic mixtures and identify the existence of systemic tumorigenic risk from cutaneous contact with promoting agents.

Pulmonary toxicity of inhaled coal liquid aerosols (boiling range 230–450°C)☆

The biological activity of materials produced in the direct liquefaction of coal is being assessed by a variety of test systems. In this study, the pulmonary toxicity of process solvent (PS) from the solvent refined coal-I (SRC-I) process was determined by histamine aerosol challenge tests and pulmonary function and morphologic evaluations. Guinea pigs inhaled aerosols of PS (boiling range, 230 to 450 degrees C) for 6 hr/day, 5 day/week, for up to 12 days in three different experiments. In the first experiment, 8-week-old animals inhaled 0 (controls), 0.15, or 0.60 mg/liter PS aerosols with a mass median aerodynamic diameter (MMAD) of 1.3 micrometer. Exposure to 0.15 mg/liter PS for 12 days resulted in depressed weight gain and marked hypersensitivity to inhaled histamine compared with sham-exposed control animals. Four of five animals exposed to 0.6 mg/liter PS died of respiratory failure during exposure. During the second experiment, 14-week-old animals inhaled 0 (controls) or 0.19 mg/liter PS (MMAD, 1.3 microns) for 1, 3, or 12 days. Hypersensitivity to aerosolized histamine occurred only after 12 days exposure to PS aerosols. At that time, morphologic lung evaluations showed mild to moderate pneumonitis and accumulation of exudate in bronchioles of PS-exposed animals. In the third experiment, pulmonary function evaluations were conducted on 4-week-old animals exposed to 0 (controls) or 0.19 mg/liter PS for 8 days. Functional changes measured in these animals (compared to controls) included increased gas trapping at low lung volumes, decreased quasi-static compliance, and decreased diffusion capacity of the lung for carbon monoxide. These studies showed that measurable changes in lung function were produced in guinea pigs after 8 to 12 days exposure to 0.15 or 0.19 mg/liter PS and that exposure to PS affected weight gain only in younger animals (4 and 8 weeks old) but not in 14-week-old animals.

Neptunium-237 toxicity in the rat: II. Intracellular distribution of neptunium and cerium in rat liver

Abstract The subcellular distribution of neptunium in rat liver was determined at various dose levels and times. Males and females had similar subcellular distributions when the dose was very low with the soluble fraction showing the highest concentration. Increasing the dose resulted in a differential shift in the subcellular distribution pattern for males and females. Females showed the highest concentrations in the nuclear fraction while the males had the highest levels in the mitochondrial fraction. Simultaneous administration of CCl4 with tracer levels of neptunium to males caused a shift in the pattern to one similar to that seen with females at higher dose levels. Similar experiments were performed with cerium; again, administration of a higher dose resulted in a pattern quite different from that seen when tracer doses were used.

Effects of subchronic inhalation exposure of mice to a high-boiling coal liquid

Mice (CD-1) were exposed to aerosol concentrations of 0.0, 0.03, 0.14, or 0.69 mg/liter of heavy distillate (HD), a high-boiling coal liquid from the solvent-refined coal (SRC)-II process. Exposures were for 6 hr/day, 5 days/week for 13 weeks. Particle sizes ranged between 1.6 and 1.8 micron, mass median aerodynamic diameter, with a geometric standard deviation range of 1.9-2.5. Growth for high-dose males was significantly less than that of the control group. Compared to controls, weights of liver were significantly higher and those of ovaries and thymus significantly lower; these changes were significant on both absolute and relative weight bases. The number of red blood cells, volume of packed red cells, and hemoglobin concentration for animals from the high-dose group were significantly lower than those of controls. Microscopic examination of organ sections showed focal hepatic necrosis and nonspecific hepatopathy. Additionally, olfactory epithelial degeneration occurred in a dose-dependent manner. Results from this study indicated that exposure to HD caused adverse effects at the high dose and that these changes were either less severe or absent in middle-dose group mice. Comparison of these results with those for rats indicated that with rats the biological effects were more severe and present at lower doses than was observed for mice.

Generation and delivery of coal liquid aerosols for inhalation studies

To aid in the toxicologic evaluation of solvent refined coal (SRC) materials, we developed an aerosol generation system for whole-body inhalation exposure of experimental animals to coal liquids. The main components of the exposure system were an aerosol generator, a manifold for delivery of the aerosol, three exposure chambers and an exhaust system. High-boiling coal liquids from the SRC-I and SRC-II processes were used as test materials. Aerosol concentrations were measured by drawing aerosol samples from the chamber through a Metricel filter and eluting the coal liquid into chloroform. Since these coal liquids have an ultraviolet absorption peak at 254 nm, the absorbance was determined at this wavelength. As part of the experiment, we evaluated the Solo-Sphere,® Retec® and Collison neubulizer as aerosol generators for the coal liquids. Both the Solo-Sphere and Retec provided adequate concentrations of respirable particles; however, aerosol concentrations within the exposure chamber were more consistent...

Phenotypically selective promotion of diethylnitrosamine-initiated altered hepatocyte foci by dietary phenobarbital or a topically applied coal-derived organic mixture in male and female rats☆

Relative frequencies of diethylnitrosamine (DEN)-initiated foci of altered hepatocytes appearing in response to promotion by either dietary phenobarbital or a topically applied coal-derived organic mixture (CDM) were investigated in male and female rats. The focus population was examined for two histochemical markers, elevated gamma-glutamyl transpeptidase [GG(+)] and iron exclusion [FE(-)], giving rise to 3 detectable focus phenotypes, i.e., GG(+) foci, FE(-) foci, and GG(+)/(FE(-) foci. Frequencies of the 3 phenotypes were quantitated through the use of serial frozen sectioning and computer-assisted image analysis. In agreement with our prior observations, cutaneous exposure to CDM or dietary phenobarbital promoted the expression of DEN-initiated foci. However, the current data showed that this promoting effect of CDM occurred only in females and was restricted to foci with the GG(+)/FE(-) phenotype. Dietary phenobarbital, on the other hand, promoted both the GG(+) and GG(+)/FE(-) phenotypes and was effective in both males and females, although a sex-related differential in the promoting efficiency of phenobarbital was also observed. The pronounced heterogeneity in the responses of the 3 focus phenotypes suggests that each phenotype is the consequence of a specific type of genomic alteration with a specific capacity to undergo phenotypic expression in response to a given promoting stimulus.

Influence of hepatocarcinogen feeding on the retention of cerium-144 by the liver

Abstract Dietary administration of DAB, DAF, or ethionine to rats injected with 144 Ce caused an increased retention of the radionuclide by the liver. The 144 Ce content of spleen, kidney, and femur was little affected by the carcinogen feeding. The increased retention of 144 Ce by the liver was associated with decreased biliary and fecal levels.