Human health effects of exposure to cadmium.

The health effects of human exposure to cadmium are discussed with emphases on intake, absorption, body burden, and excretion; osteomalacia in Japan; hypertension; and proteinuria, emphysema, osteomalacia, and cancer in workers. Elevated blood pressure has not been observed as a result of excessive exposures to cadmium in Japan or the workplace. Renal tubular dysfunction and consequent proteinuria is generally accepted as the main effect following long-term, low-level exposure to cadmium. Studies of workers show that proteinuria may develop after the first year of exposure or many years after the last exposure. Proteinuria and deterioration of renal function may continue even after cessation of exposure. The immediate health significance of low-level proteinuria is still under debate. However, there is evidence that long-term renal tubular dysfunction may lead to abnormalities of calcium metabolism and osteomalacia. The few autopsy and cross-sectional studies of workers do not permit conclusions to be drawn regarding the relationship between cadmium exposure and emphysema. Retrospective and historical-prospective studies are needed to settle this important question. No conclusive evidence has been published regarding cadmium-induced cancer in humans. However, there is sufficient evidence to regard cadmium as a suspect renal and prostate carcinogen. Because of equivocal results and the absence of dose-response relationships, the studies reviewed should be used with caution in making regulatory decisions and low-dose risk assessments.

Detection of chrysotile asbestos in workers' urine.

Urinary asbestos concentrations were evaluated as an indicator of occupational exposure to chrysotile asbestos via inhalation and ingestion. Detection of asbestos in the urine represents the first step in developing a biological indicator of exposure. Such an indicator could be used to supplement exposure data from workplace air sampling. A biological indicator would be particularly valuable in evaluating workers with intermittent airborne asbestos exposures and in determining if airborne exposure results in penetration of asbestos through the lung or gastro-intestinal tract. Transmission electron microscopy was selected as the most sensitive technique for identification of all sizes of asbestos fibers which might appear in the urine. First morning void urine samples were obtained from six workers (occupationally exposed to chrysotile asbestos in a factory producing roof coatings) and from a control group (six individuals with no occupational exposure). The levels of chrysotile asbestos detected in the urine of five workers were significantly greater than the asbestos concentrations in matched field blanks (both on a number and mass basis). Field blanks were designed to detect asbestos in the urine samples due to contamination which might occur during urine collection. Also, the workers' urinary asbestos levels were significantly greater than the concentrations found in the control group (both on a number and mass basis). Finally, the levels of chrysotile asbestos detected in the urine of two of six controls were significantly greater than those in matched field blanks (both on a number and mass basis). Although the project was not specifically designed to correlate urinary and airborne asbestos concentrations, preliminary data indicated that a correlation did not exist between these factors.

Migration of ingested asbestos.

Tissue samples from one test and one control baboon were analyzed by transmission electron microscopy for the presence of chrysotile and crocidolite asbestos. The test animal had been gavaged with cumulative doses of 800 mg each of chrysotile and crocidolite asbestos. An earlier evaluation of these tissues led to the conclusion that ingested asbestos fibers do not penetrate the gastrointestinal tract of the baboon and migrate systemically. However, the present study involved more sensitive methodology, and penetration and migration were clearly demonstrated by the recovery of significant levels of asbestos from test stomach, heart, spleen, pancreas, and blood samples.

Detection of chrysotile asbestos in workers' urine.

Urinary asbestos concentrations were evaluated as an indicator of occupational exposure to chrysotile asbestos via inhalation and ingestion. Detection of asbestos in the urine represents the first step in developing a biological indicator of exposure. Such an indicator could be used to supplement exposure data from workplace air sampling. A biological indicator would be particularly valuable in evaluating workers with intermittent airborne asbestos exposures and in determining if airborne exposure results in penetration through the lung or gastrointestinal tract. Transmission electron microscopy was selected as the most sensitive technique for identification of all sizes of asbestos fibers which might appear in the urine. First morning void urine samples were obtained from six workers (occupationally exposed to chrysotile asbestos in a factory producing roof coatings) and from a control group (six individuals with no occupational exposure). The levels of chrysotile asbestos detected in the urine of five workers were significantly greater than the asbestos concentrations in matched field blanks (both on a number and mass basis). Field blanks were designed to detect asbestos in the urine samples due to contamination which might occur during urine collection. Also, the workers' urinary asbestos levels were significantly greater than the concentrations found in the control group (both on a number and mass basis). Finally, the levels of chrysotile asbestos detected in the urine of two of six controls were significantly greater than those in matched field blanks (both on a number and mass basis). Although the project was not specifically designed to correlate urinary and airborne asbestos concentrations, preliminary data indicated that a correlation did not exist between these factors.

Human health effects of exposure to cadmium.

The health effects of human exposure to cadmium are discussed with emphasis on intake, absorption, body burden, and excretion; osteomalacia in Japan; hypertension; and proteinuria, emphysema, osteomalacia, and cancer in workers. Elevated blood pressure has not been observed as a result of excessive exposures to cadmium in Japan or the workplace. Renal tubular dysfunction and consequent proteinuria is generally accepted as the main effect following long-term, low-level exposure to cadmium. Studies of workers show that proteinuria may develop after the first year of exposure or many years after the last exposure. Proteinuria and deterioration of renal function may continue even after cessation of exposure. The immediate health significance of low-level proteinuria is still under debate. However, there is evidence that long-term renal tubular dysfunction may lead to abnormalities of calcium metabolism and osteomalacia. The few autopsy and cross-sectional studies of workers do not permit conclusions to be drawn regarding the relationship between cadmium exposure and emphysema. Retrospective and historical-prospective studies are needed to settle this important question. No conclusive evidence has been published regarding cadmium-induced cancer in humans. However, there is sufficient evidence to regard cadmium as a suspect renal and prostate carcinogen. Because of equivocal results and the absence of dose-response relationships, the studies reviewed should be used with caution in making regulatory decisions and low-dose risk assessments.

High sodium in drinking water and its effect on blood pressure.

A recent study of two communities in Massachusetts showed that a group of high school sophomores exposed to 107 mg/liter sodium in their municipal drinking water had significantly higher systolic and diastolic blood pressures than a control group exposed to 8 mg/liter. The present study was undertaken to determine if these results could be repeated in two communities, LaGrange and Westchester, located in the Chicago metropolitan area. These communities have similar demographic and socioeconomic characteristics. However, the concentration of sodium in the municipal drinking water of LaGrange is 405 mg/liter as compared to 4 mg/liter for Westchester. A comparison was made between the blood pressures of high school juniors and seniors from the two communities. Of the 386 eligible students in LaGrange, 84% volunteered to have their blood pressures taken. In Westchester, 78% of the 401 eligible students volunteered. Results of the survey indicated that male and female systolic blood pressures in the high sodium community were not significantly higher than those in the low sodium community. Surprisingly, the observed systolic blood pressures of males in the lower sodium community were higher than those in the high sodium community. These findings did not corroborate the results of the Massachusetts study. However, the male and female diastolic blood pressures were significantly higher (p = 0.040 for males and p = 0.016 for females) in the high sodium community. The increases in diastolic blood pressures (approximately 2 mmHg for males and females) were not as large as those observed in the Massachusetts study (2.7 and 5.1 mmHg for males and females, respectively).

Asbestos fibers: 1. A modified preparation of tissue samples for analysis by electron microscopy. 2. Presence of fibers in tissues of baboon fed chrysotile asbestos.

A specimen preparation technique is described which yields uniformly dispersed particles on transmission electron microscope (TEM) grids. It is relatively rapid and probably incurs no fiber loss. This technique was used to test the hypothesis that orally administered chrysotile asbestos may pass through the wall of the gastrointestinal tract (GI) of the neonate baboon. A test neonate baboon was bottle-fed chrysotile asbestos which was suspended in a milk formula. Control and test baboons were sacrificed at the end of a 9-day feeding period, and several tissues were removed and preserved. Kidney, liver, and spleen tissues were prepared for TEM analysis. Tissues from the control animal showed no fibers. The number of chrysotile fibers recovered from the test kidney cortex was significantly higher than the level found in the control kidney cortex (p less than 0.005). The frequency distribution of fibers lengths in the kidney cortex was very similar to that of the feeding suspension. This study suggests that a wide range of fiber sizes can penetrate the GI tract and migrate.

Experimental design and statistical analysis of an in-use test of germicidal detergents.

Present methodology for the in-use testing of germicidal detergents is too time-consuming for routine use by a hospital environmentalist. A simplified experimental design and statistical analysis, amenable to routine use, is presented for the in-use testing of germicidal detergents against water alone. As an illustration of our methodology we evaluated two germicidal detergents versus water alone. Under our conditions of use, it was found that water alone was equally and significantly as effective (p less than 0.001) as the two germicidal detergents in reducing microbial contamination of floors.

Precision of analysis for waterborne chrysotile asbestos by transmission electron microscopy.

Detailed examinations of water samples were carried out to determine the precision of analysis for chrysotile asbestos by transmission electron microscopy (TEM). Since the frequency distribution of counts fits a Poisson distribution, several statistical inferences were made, including (1) an estimate of precision, and (2) a model for determining the probability of observing chrysotile as a function of its concentration in water and magnitude of area scanned by TEM.

A review of the health effects of ingested asbestos.

Occupational studies indicate that a human health hazard may exist for ingested asbestos since the death rates due to digestive system cancers are elevated in asbestos workers. This finding may be related to the swallowing of asbestos that was inhaled and cleared from the respiratory system via the respiratory clearance mechanism. Published animal ingestion experiments have serious shortcomings in their design and execution which make their interpretation very difficult. Animal ingestion and human autopsy studies suggest that asbestos fibers may penetrate the digestive tract and migrate to other locations in the body.