Richard D. Stewart

Experimental Human Exposure to Methylene Chloride

Inhalation of methylene chloride vapor In concentrations of 500 to 1,000 ppm for one to two hours was followed promptly by a sustained elevation of carboxyhemoglobin level in all 11 subjects studied. The evidence suggests that carbon monoxide may fee a metabolite of methylene chloride and that exposure to concentrations of methylene chloride that do not exceed the Industrial Threshold Limit Value for that solvent may result in a carboxyhemoglobin saturation level in excess of that allowable from carbon monoxide itself. In addition, methylene chloride produced signs and symptoms of central nervous system depression in subjects exposed to vapor concentrations of 1,000 ppm.

Carboxyhemoglobin Elevation after Exposure to Dichloromethane

Inhalation of dichloromethane vapor in concentrations of 500 to 1000 parts per million for 1 to 2 hours promptly initiated the formation of significant quantities of carbon monoxide in human subjects. The evidence suggests that carbon monoxide may be a metabolite of dichloromethane and, that exposure to concentrations of dichloromethane below the industrial threshold limit values may result in the formation of carbon monoxide in amounts that exceed the allowable limits.

Expired-Air Acetone in Diabetes Mellitus

SINCE Lerch suggested in 1874 that the characteristic odor in a diabetic patients breath was acetone several methods for measuring this compound in breath have been devised.1 2 3 4 5 In the small ...

Use of breath analysis to monitor trichloroethylene exposures.

Triehloroethylene (TCE) postexposure breath decay curves were obtained from ten male and ten female volunteers who were exposed daily in a controlled-environment chamber to TCE vapor, 20, 100, or 200 ppm for one, three, or 71/2 hours. Alveolar breath samples were collected in glass pipettes for TCE analysis by gas chromatography. The series of TCE breath decay curves obtained was highly reproducible and the narrow range of TCE in the breath at a specific time in the early postexposure period of persons identically exposed indicated that breath analysis could be used as a rapid method with which to estimate the magnitude of recent TCE exposure. The TCE breath concentration in the immediate postexposure period accurately reflected the vapor concentration to which the subject had been most recently exposed. Breath samples collected eight to 24 hours following exposure were accurate indicators of the time-weighted average vapor exposure experienced by the subject on the previous day.

Experimental human exposure to propylene glycol dinitrate

Abstract Human volunteers were exposed in a controlled-environment chamber to propylene glycol dinitrate vapor at concentrations of 0.03, 0.1, 0.2, 0.35, 0.5, and 1.5 ppm. Physiological and central nervous system responses to the exposures were monitored. Exposure to concentrations of 0.2 ppm or greater produced disruption of the organization of the visual evoked response (VER) and headache in the majority of subjects. Subjects repeatedly exposed to 0.2 ppm for 8 hr on a daily basis developed a tolerance to the induction of headaches, but the alteration in VER morphology appeared cumulative. Marked impairment in balance became manifest after exposure to 0.5 ppm for 6.5 hr, while 40 min of exposure to 1.5 ppm added eye irritation to the list of symptoms.

The Effect of Carbon Monoxide on Time Perception, Manual Coordination, Inspection, and Arithmetic

The first untoward effect of carbon monoxide (CO) upon healthy man is reported to be a gross impairment in his ability to distinguish between short intervals of time and to estimate 30-sec intervals (Beard and Wertheim, 1967). Alarmingly, these decrements in time perception are reported to be produced by exposures to CO at concentrations as low as 50 parts per million (ppm) for 90 min, exposures which are currently acceptable in American industry (ACGIH, 1972), commonly encountered by urban populations, and much lower than those experienced by the average adult smoking one pack of cigarettes per day (Surgeon General, 1972).

Absence of Circulating Interferon in Patients with Malaria and with American Trypanosomiasis

Summary Interferon could not be detected in 50 sera obtained during the acute illness from 42 patients with clinical malaria. Similarly negative results were obtained when 40 sera from patients with subclinical T. cruzi infection were studied. The authors thank Dr. Wendell H. Hall from the Minneapolis V.A. Hospital who provided some of the malarial sera. Miss J. Balay provided capable technical assistance. Studies of Chagas disease were supported in part by a grant-in-aid from the S. C. Johnson Foundation.

Methods developed for the mass sampling analysis of CO and carboxyhemoglobin in man

Gas chromatography was used to quantitate CO in air and also as an indirect means of determining %COHb in blood. The blood was then used to calibrate four CO-Oximeters used in a survey to determine average COHb levels in various segments of the U.S. population. Mean differences, both between the two methods of analysis and between pairs of CO-Oximeters were less than 0.1% COHb saturation. COHb values obtained on consecutive days using one CO-Oximeter were repeatable within a S.D. +/- 0.13% COHb.

Human Absorption of Carbon Monoxide from High Concentrations in Air

Six healthy males were exposed to carbon monoxide concentrations ranging from 1000 ppm to 35,600 ppm for periods of controlled duration and the rate of rise of carboxyhemoglobin concentrations in blood was determined. The rate of increase was found to be accurately predicted by the relationship, log (δ% COHb/liter) equals 1.036 log (ppm CO inhaled) minus 4.4793. This relationship may be used to determine the carbon monoxide absorbed in brief exposures to high concentrations.

Improved Neurological Hammer

To the Editor:— Many clinicians desiring a softer, more compressible rubber head for their neurological hammers than those of standard models, hand carve the heads from soft rubber stock such as that used for lead pencil erasers. In an attempt to fashion a neurological hammerhead with the desired softness but which also would be durable, a series of heads were made from various silicone-rubber formulations. Twelve hammerheads with initial durometer measurements of 24 were hand-fashioned from the bulk polymer and have been kept in constant clinical use for six years. Six of the hammers were used in an isolation unit where they have been subjected to over 100 routine autoclavings. Durometer measurements remained constant. Silicone rubbers for neurological hammerheads provide the clinician with a durable instrument with properties of compressibility and softness which are not altered by time or autoclaving.