Morris M. Joselow

Absorption and excretion of mercury in man. XV. Occupational exposure among dentists.

To evaluate the occupational hazard of the use of mercury by dentists, determinations were made of 1) the total mercury and vapor concentrations in a group of urban dental offices; and 2) the urinary excretion of mercury by the dentists. In a small but significant proportion (14%) of these offices, mercury concentrations were found in excess of the threshold limit value, implying a lack of care in handling mercury. The average total mercury concentration was more than twice the average vapor concentration, clearly inferring that mercury particulates cannot be ignored in assessing the dental work environment. Absorption of mercury was evidenced by higher than normal urinary mercury levels, which correlated well with both the total ambient air concentrations and estimated exposure times. 28 references, 5 tables.

Lead absorption in children and its relationship to urban traffic densities.

The relationship between blood-lead levels in children and household location with respect to distances from major arterials and traffic density in the city of Newark, NJ, is examined. The findings confirm that the occurrence of excessive lead absorption in children is increased by household proximity to major urban highways or heavy traffic density. The inhalation of automobile exhausts is thus imputed as an important factor in the etiology of childhood lead poisoning in urban areas.

Absorption and excretion of mercury in man. XIV. Salivary excretion of mercury and its relationship to blood and urine mercury.

The relationships among the mercury contents of salivary (parotid gland) secretions and simultaneously obtained blood and urine specimens were examined quantitatively among a group occupationally exposed to several mixed mercurials. Mercury concentrations in saliva averaged 1/4 and 1/10 of the blood and urinary concentrations, respectively. A high correlation was observed between blood and parotid fluid mercury contents, inferring that the readily obtainable parotid secretion may be of diagnostic value as an indirect monitor of blood mercury as well as other other foreign substances in the blood.

Absorption and excretion of mercury in man. XI. Mercury content of " normal" human tissues.

Mercury analyses were performed on 236 samples of tissues removed at autopsy from 39 normal human subjects. The samples represented 12 different tissues or organs. The highest values were found in the kidneys. Age did not appear to be a factor in the mercury levels. 14 references, 2 tables.

Absorption and excretion of mercury in man. XII. Relationship between urinary mercury and proteinuria.

Using a sensitive method for the quantitative determination of total urinary protein, a mild proteinuria has been demonstrated in a working population chronically exposed to a relatively high concentration of the vapors and dusts of mixed organic (phenyl) and inorganic mercury compounds. The mean urinary protein content (9 mg/100 ml) of this exposed group was significantly higher than the mean urinary protein content (5.3 mg/100 ml) of a control unexposed group. For the exposed group, the urinary protein levels correlated well with the urinary mercury contents (with a statistical probability of such correlation less than 1%, as determined by the Spearman rank order correlation method). For the exposed group, the urinary protein levels showed a weak correlation (significance between 5% and 10%) with blood mercury contents. In both instances the correlation was found only on a group basis.

Application of the zinc protoporphyrin (ZP) test as a monitor of occupational exposure to lead

Zinc protoporphyrin, the predominant abnormal metabolite that appears in whole blood as a result of chronic lead absorption, can be assayed fluorometrically in diluted whole blood with great sensitivity. An extremely simple and rapid test for the effects of lead absorption is described that is based on this assay. Results of a field trial show a characteristic dose-response relationship between zinc protoporphyrin and lead, and indicate that this test should be seriously considered as a monitor for the effects of chronic lead adsorption.

A Micro-Method for the Collection and Analysis of Trace Metals by Paper-in-a-Cup Atomic Absorption Spectrophotometry

Concentrations of toxic metals can be determined in a drop of blood, such as might be obtained from a finger-prick, by spotting the blood onto filter paper, drying it, and then burning a standard size disc punched from the filter paper in an atomic absorption spectrophotometer. Results for lead, cadmium and zinc determined in this manner compare favorably with accepted macro-methods of analysis. The advantages of this procedure, namely the ease of specimen collection and the simplicity of the analysis, may make this the method of choice in biochemical monitoring for trace metal absorption by workers.

Distribution of thallium and lead in children's blood.

Mean whole blood concentrations for lead and thallium were determined by atomic absorption spectrophotometric analysis for children residing in Newkark, NJ. Frequency distributions for the various concentration ranges for both metals were recorded. There is no noticeable correlation between the lead and thallium content of whole blood, which suggests that exposure to and/or absorption of these substances are different.

Micro analysis for lead in blood with built-in contamination control.

A built-in check for false positives for the determination of lead in microliter blood specimens is available through the quantitative measurement of free erythrocyte protoporphyrin (FEP), a metabolite that is closely and directly correlated with the lead content of blood. The measurement of FEP, which is not an environmental contaminant, can thus serve as a check on the validity of findings of high lead content. The paper-in-a-cup system for the collection and atomic absorption determination of lead on finger-prick blood specimens lends itself readily to the determination of FEP, since spots collected on the filter paper can also be analyzed for FEP. Such analyses, limited only to blood specimens showing high lead values, have helped considerably in eliminating the false positives due to contamination, and permit reliance on blood lead determinations wth a high degree of confidence.