Larry L. Hall

Dermal irritancy of metal compounds. Studies with palladium, platinum, lead, and manganese compounds.

Dermal irritancy of 14 materials, including several compounds of palladium, platinum and lead, and methylcyclopentadienyl manganese tricarbonyl, plus deionized water (negative control) and glacial acetic acid (positive control), was tested on male albino rabbits weighing 2 to 3 kg. Procedures and evaluation criteria were adopted from those in use by the National Institute for Occupational Safety and Health. Five materials were evaluated as unsafe for intact or abraded skin contact as judged by severity of responses: glacial acetic acid (C3H5PDCl)2, (NH4)2PdCl4, (NH4)2PdCl6, and PtCl4; one as safe for intact, but not for abraded, skin: K2PdCl6; and two as safe for intact skin but not for abraded skin unless protected: K2PdCl4 and PdCl2. The remainder were evaluated as safe for intact or abraded skin contact (irritancy grade less than 1 on a scale of 4): H2O, Pd(NH3)2Cl2, PdO, PtO2, PtCl2, PbCl2, PbO, MMT.

Use of exposure databases for status and trends analysis

Exposure databases are useful for monitoring status and trends in environmental health. However, other supporting data are usually needed to infer human exposure or internal dose. Program planning and evaluation, environmental health surveillance, epidemiologic research, and contributions to international efforts are four major purposes for monitoring environmental exposure status and trends. Although databases play an important role in monitoring human exposure, certain methodological problems need to be overcome. The work group developed six criteria for meeting information needs for human exposure assessment. Areas that need attention are (1) specification of location, (2) specification of facility and chemical identifiers, (3) documentation of special populations at risk, (4) provision of early warning of new problems, (5) monitoring changes over time, and (6) enhancement of documentation. We tested these criteria by examining six available databases that might be used for monitoring exposure to contaminants in drinking water. Available data fell short of information needs. We drew four conclusions and offered several recommendations for each. First, available data systems lack adequate measures of human exposure. Second, data for monitoring exposures for many important population subgroups and environmental settings are inadequate. Third, an early warning system that monitors human exposures is needed. Fourth, designers of data-collection systems should consider the needs of users who monitor status and trends of human exposure.

Defluorination of fluoroacetate in the rat.

Abstract Rats given 5 ppm F as FAc (equivalent to 26 ppm of NaFac) in the drinking water for approximately four months deposited as much fluoride in the skeletal system as did rats receiving 5 ppm F as NaF in the water. Little evidence could be found for the presence of organically bound fluoride in bone after ingesting FAc, though an appreciable proportion of skeletal fluoride deposited when NaF was ingested was shown not to respond to the fluoride ion electrode. The daily urinary excretion of total fluoride after FAc was somewhat greater than after NaF; about two thirds of this fluoride responded to the electrode, whereas more than 90 percent of the total fluoride after NaF was ionic in nature. The data are interpreted as showing that the rat is capable of splitting the C-F bond in FAc and/or in its fluoride-containing metabolites, with subsequent skeletal storage and renal excretion of the released fluoride ion. The chronic administration of this low level of FAc caused an early but temporary retardation of growth. The Krebs cycle was interfered with, as evidenced by increased concentrations of citrate in the kidney and urine. At termination of the experiment, histological examination of the testes showed that the FAc had induced severe damage characterized by massive disorganization of the tubules, nearly total loss of functional cells, absence of sperm, and damage to the Sertoli cells.

Metabolic aspects of methylcyclopentadienyl manganese tricarbonyl in rats.

Whole-body retention, excretion, and tissue distribution of 54Mn were studied in rats following oral and intravenous dosing of methylcyclopentadienyl 54manganese tricarbonyl (MMT). An initial rapid excretion of most of the 54Mn occurred following both routes of exposure. Extraction of the urine and feces after dosing indicated that the MMT was metabolized and that the 54Mn was excreted in the inorganic form. The high levels of 54Mn found in the urine after MMT dosing are not typical of normal Mn excretion. The liver, kidneys, and lungs contained the highest concentrations of 54Mn following administration of MMT. n nIn vitro experiments indicated that MMT was metabolized in the liver, lung, kidney, and to a small extent in the brain. Metabolism of MMT by kidney homogenate supported the hypothesis that biotransformation occurred in the kidney and explains the high levels of urinary excretion of inorganic 54Mn. n nThe whole body retention curves for 54Mn labeled MMT and 54Mn Cl2 were very similar and are consistent with the hypothesis that MMT is rapidly metabolized. Both curves for 54Mn reflect the kinetics of inorganic Mn.