Scanning electron microscopy determination of string mozzarella cheese in gastric contents.

As part of a suspected homicide investigation, a sampling of the gastric contents from the victim was forwarded to the U.S. Food and Drug Administration's Forensic Chemistry Center (FCC) for analysis of specific, selected components. The victim was known to have consumed string mozzarella cheese, as a snack, less than 24 h before his disappearance and the subsequent discovery of the body. The investigation sought to confirm or dismiss speculation the victim may have been fed a meal or eaten additional food prior to his death. Analysis of the stomach contents involved examination by stereoscopic light microscopy (SLM) and isolation, processing, and analysis of suspect materials by scanning electron microscopy (SEM). Several wax-like, off-white to cream-colored objects were noted by SLM examination and removed from the gastric contents. Through a series of fixation, sectioning, drying, and coating steps, these objects were prepared for analysis by SEM. Comparison of the suspect material with laboratory control string mozzarella cheese showed excellent correlation between the analyzed samples, confirming the suspect material from the stomach contents as string mozzarella cheese.

Supermarket tampering: cocaine detected in syringes and in fruit.

Product tampering, as detailed by the Federal Anti-Tampering Act of 1983 (1), is a felony punishable by both fine and imprisonment. The rationale for product tampering ranges from pranks and attention seeking acts to extortion, terrorism, and homicide. One such case submitted for analysis involved four medical syringes found in a supermarket and suspected of being used to tamper with various products. One of the syringes was found piercing a pear while the other three syringes were found with needles exposed in other parts of the supermarket. Microscopic analysis was used to collect residue from the syringe barrels and the pear. A multidiscipline approach involving SLM, PLM, including microchemical analysis, FTIR, and GC/MS analyses, performed on the residual liquid found in the syringe barrels and in the suspect pear, confirmed the presence of cocaine. This multidisciplinary approach is often necessary when there is a possible health risk to the public and rapid response is important. With this approach, it was quickly determined which drugs or poisons were used in this tampering.

Fibrogenic potentials of coal slags used as abrasive blasting substitutes.

This study was designed to examine the fibrogenic potentials of four coal slags that are being used as substitutes for silica sand in abrasive blasting. Six groups of 100 male Sprague-Dawley rats, including four coal slag groups, a vehicle control, and a positive control for fibrosis (Minusil quartz), were used. Each dust treatment group was given a single 40-mg dose of test agent via intratracheal instillation. Interim sacrifices of 15 animals per group were performed at 2 d, 3 mo, and 6 mo posttreatment, with the terminal sacrifice conducted at 12 mo. Hematoxylin and eosin stained histologic sections were prepared from designated formalin-fixed tissues collected at each necropsy and examined microscopically. Pulmonary silicon analyses were performed for each group at the 2-d and 12-mo sacrifices. Pulmonary function analyses were conducted for each group at the 3-, 6-, and 12-mo sacrifices. Lung hydroxyproline analyses were conducted for 15 animals in each group at the terminal sacrifice. The pulmonary fibrogenic potentials of the four coal slag groups were compared histologically with the Minusil and vehicle controls. A mild to moderate interstitial fibrosis, which was progressive with time, was noted in each of the coal slag groups. However, the coal slag-induced lung fibrosis was much less than that produced by Minusil. Differences in fibrosis among the individual coal slags were relatively minor and certainly not as striking as those between the slags and Minusil. Other data derived from this study, such as lung hydroxyproline content, pulmonary particulate burdens, pulmonary function, and animal body weights, provided further evidence of a reduced toxicity for the coal slags compared to Minusil.

The classification of asbestos fibres by scanning electron microscopy and computer-digitizing tablet.

Because of the need to completely and accurately size asbestos bulk samples for toxicity studies, a method was developed to classify asbestos fibres using enlarged micrographs originally produced on the scanning electron microscope (SEM). Individual fibre length and width measurements were performed on a computer-assisted, digitizing tablet. This method, though time consuming, permitted the sizing of all fibres (length and width) and particles (area) in selected fields of view at SEM magnifications of x100 and x2500. Final enlargement of the micrographs permitted sizing magnifications of x10,000. Seven distinct asbestos samples were classified including five chrysotile and two crocidolite samples. Statistical analyses showed good interfilter fibre size correlation for all types of asbestos. In addition, it was determined that a representative sizing of all fibres and non-fibrous particles on a filter preparation could be performed using five sets of micrographs taken at a magnification of x2500 and enlarged to x10,000: an inverse square root transformation (-0.5 power) is needed to normalize the distributions of length and width.

Lung particulate burdens of subjects from the Cincinnati, Ohio urban area.

Because of the relatively small data base existing for lung particulate burdens of subjects with no overt pneumoconioses, the total exogenous lung particulate concentrations of 91 subjects from the Cincinnati, Ohio urban area were determined using an automated scanning electron microscope-energy dispersive x-ray analysis-image analysis system. Four of these subjects were foundry workers and had the highest exogenous particle concentrations seen in the 91 lungs, ranging from 1860 to 2990 x 10(6) particles per gram of dry lung (ppg). The average exogenous particle concentration for the remaining 87 subjects was 476 +/- 380 x 10(6) ppg with a range of 71 to 1860 x 10(6) ppg. The median size of the exogenous particles in the 87 lungs was narrow, ranging from 0.37 to 1.02 microns. The geometric mean particle size over all 87 lungs was 0.60 microns with a geometric standard deviation (sigma g) of 2.35. The total exogenous particle levels were elevated for the male subjects compared to females (p=0.015), and were positively associated with age (p=0.021). However, no correlation was seen between total particle concentration and race or smoking history.

Fibrogenicity and carcinogenic potential of smelter slags used as abrasive blasting substitutes.

This study was designed to examine the fibrogenic and carcinogenic potentials of three smelter slags (primary copper slag, secondary copper slag, and nickel slag) that have been used for a number of years as substitutes for sand in abrasive blasting operations. Seven groups of 85 male Fischer 344 rats (approximately 180 g) were used. Each group was given a single 20-mg dose of one of the following test materials via intratracheal instillation: primary copper slag, secondary copper slag, nickel slag, feldspar, Min-U-Sil, novaculite, or vehicle control. Chemical, particle size, and surface area analyses were performed for each test dust. Animals were weighed monthly, and ten animals per group were necropsied at the 6-, 12-, and 18-mo interim sacrifices. The terminal sacrifice was conducted at 22 mo. Hematoxylin and eosin stained histologic sections were prepared from designated formalin-fixed tissues collected at necropsy and examined microscopically. The pulmonary fibrogenic and carcinogenic potentials of the three smelter slags were compared histopathologically with feldspar, novaculite, Min-U-Sil, and vehicle controls. Only minimal to slight alveolar wall fibrosis was seen in the two copper slag groups, while the response seen with nickel slag was consistent with a foreign body reaction with minimal fibrosis seen in only an occasional animal. The major reaction seen in both the feldspar- and the novaculite-treated rats was a granulomatous inflammation with varying degrees of fibrosis associated with the granulomas. Significant numbers of primary lung tumors, principally adenocarcinomas and adenomas, were seen in the copper slag (p = 0.005 and p = 0.022 for the primary and secondary slags, respectively), in the feldspar (p = 0.007), in the novaculite (p less than 0.001), and in the Min-U-Sil (p less than 0.001) groups when compared to the vehicle control group. In addition, the Min-U-Sil and novaculite groups had significantly elevated pulmonary tumor proportions relative to the other treatments (p less than or equal to 0.002), with the Min-U-Sil being higher than the novaculite (p = 0.012). On the basis of the tumor incidence data, one must conclude that both copper slags tested in this study are carcinogenic to rats.

Sperm viability: a comparison of analytical methods.

Two methods of measuring human sperm viability, the stain exclusion assay and the hypoosmotic swelling (HOS) test, were evaluated. Human sperm were pretreated with 2.0% glutaraldehyde or 0.1% Triton X-100 and compared to untreated controls. Approximately one half of the sperm were found to be viable in the control samples and nearly all sperm were non-viable in the Triton X-100 treated samples by both the stain exclusion and HOS assays. After glutaraldehyde pretreatment, presumably inactivating the spermatozoa, the HOS test revealed that most sperm were not viable, while the stain exclusion test found no difference between glutaraldehyde pretreated sperm and control sperm. Investigations with scanning and transmission electron microscopy demonstrated that the HOS test caused the membrane of the sperm tail to swell and the tail fibers to coil several times within the swollen membrane. It is concluded that the stain exclusion assay merely measures the structural integrity of the sperm membrane, whereas the HOS test also provides an indication of the physiological integrity of the sperm membrane.

Chronic inhalation of short asbestos fibers.

An animal inhalation study was initiated to study the chronic biological effects of inhalation of short chrysotile asbestos fibers. Rats and monkeys were exposed for 18 months, 7 hr/day, 5 days/week to a specially prepared, chrysotile asbestos aerosol. Based upon daily chamber measurements, the mean concentration of fibers in the chamber air was 1.0 mg/m3. By phase contrast microscopy, the number of fibers greater than 5 micron in length was determined to be 0.79 fiber per cubic centimeter. Rats were autopsied for pathological and histochemical examination at 1, 3, 6, 12, 18, and 24 months after initiating exposures. No significant differences in the histochemical data were seen between the exposed and control groups. Gross and histopathologic examination of exposed and control groups of rats indicated no compound-related lesions, including fibrosis. Open lung biopsies were performed on the chrysotile-exposed and the control monkeys 28 months after initiating exposures. Histopathologic evaluation of the lung biopsy tissue showed the presence of asbestos bodies adjacent to the terminal bronchioles of the asbestos-exposed monkeys. There was no observed fibrosis in pulmonary tissue. All monkeys are being maintained for an indefinite period and observed for signs of latent pulmonary disease.

Automated characterization of particles extracted from human lungs: three cases of tungsten carbide exposure.

An automated scanning electron microscope-energy dispersive x-ray analysis-image analysis system was used to characterize particles extracted from three human lung samples which had suspected occupationally-induced lung disease. The particles were isolated from the lung tissues by low temperature ashing and deposited on Nuclepore filters. Particles in randomly selected fields of view for each filter were automatically sized, analyzed for 32 elements, and classified according to their chemistry by the system. For each of the three lung specimens, large numbers of particles were found which indicated exposure to cemented tungsten carbide products. The particle analysis data was collected at a rate of 200 particles per hour which is considerably faster than the rate at which manual, in situ analyses can be performed.