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Plasma S-sulfonate was measured in human subjects exposed continuously under controlled conditions to sulfur dioxide for periods up to 120 hours. Subjects were exposed to chamber SO2 concentrations of 0.3, 1.0, 3.0, 4.2, and 6.0 ppm and to a control exposure with ambient air. Plasma levels of S-sulfonate showed positive correlation with atmospheric sulfur dioxide; the regression line fitted to all 80 data points determined in this experiment resulted in a highly significant correlation (correlation coefficient = 0.61, p < 0.001). The slope of the regression line was an estimated increase of 1.1 ± 0.16 (S.E.) nmoles of S-sulfonate per milliliter of plasma for each ppm increment in chamber sulfur dioxide concentration.

Skin irritation and skin tumors were produced by application of beta propiolactone to mouse skin. Short term application of undiluted BPL or of its solutions in acetone or corn oil produced reactions varying from erythema to hair loss and scarring with one to six applications of 0.8 to 100 mg BPL. Lifetime painting of acetone and corn oil solutions ranging from 0.25 to 5 per cent BPL produced both papilloma and cancer on mouse skim. Tumor production was concentration related; this relationship was more sharply defined when adjustment for mortality was made by a life-table technique. Tumorigenesis by benzpyrene and BPL applied successively appeared additive.

Single breath studies designed to measure deposition of monodisperse aerosols in human subjects required specialized apparatus for the measurement of inhaled and exhaled aerosol. An apparatus was constructed consisting of a three-way valve system and anesthesia bags to contain aerosol before inhalation and after exhalation. The bags were enclosed in boxes which were connected to a spirometer which recorded volumes. The entire system was automated so that the subject inhaled (mouth breathing) a preset volume of aerosol and exhaled a preset, larger volume of air from his lungs. Volumes were controlled by a rider on the spirometer wire which activated a group of solenoid driven valves. Quantities of aerosol in the bags were determined by integrating the photocurrent from an aerosol photometer when a bag was emptied through the photometer.

A passive sampling unit based on molecular diffusion of the gas to be measured has been designed for use as a personal monitoring device. To demonstrate the applicability of the approach, the sampler was initially used to measure water vapor concentration in the air; the results showed good accuracy and reproducibility. It was then tested with sulfur dioxide as a means of measuring time-weighted average exposure to this gas. The quantity of gas transferred by diffusion from the environment through an orifice of known dimensions into a chamber maintained at substantially zero concentration by a suitable collecting medium can be used as the basis for calculating average concentration during the time the sampler is in the environment. Calculated and observed values for chamber sulfur dioxide concentrations from 10 ppm to about 0.1 ppm agreed very well over a considerable range of orifice dimensions.

During investigation of the relationship of aerosol persistence in the human respiratory tract to the dimensions of the air spaces, procedures were developed in which the subject inhaled a fixed volume of aerosol and held his breath at known lung volumes for a series of times prior to exhalation. With appropriate correcting, the persistence of aerosol could be measured as a function of time of breath holding. The distance that particles must be moved during breath holding by sedimentation or diffusion to reach a wall of the respiratory tract is determined by the size of the air spaces; the time required to reach the wall also depends on this distance. The persistence of aerosol, therefore, provides an index of the size of the air spaces containing aerosol during breath holding.

Emergency Exposure Limits are not hygienic standards to be applied to normal operations; they are intended for use in emergency planning by specialists in industrial hygiene, as described in the statement of General Principles, American Industrial Hygiene Association Journal, Vol. 25, page 579 (November-December, 1964).

The Sullivan colorimetric method can be applied satisfactorily to hydrolysates of tobacco mosaic virus if humin formation is inhibited by hydrolyzing with hydrochloric acid-titanous chloride, or better with hydriodic acid.