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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.

A new type of personal sampler for gases in air, originally reported from this laboratory, has been adapted to measurement of NO2. The sampler depends on the transfer of NO2 by diffusion to a triethanolamine coated collector at the sealed end of a tube; the open end of the tube is exposed to the test environment. The devices are accurate, light, simple to use and have very good shelf life before and after sampling.

A personal sampler system for NOx (NO + NO2) and NO2 has been developed for monitoring workplace air. The NO2 sampler previously reported from this laboratory uses triethanolamine to trap NO2 which diffuses through a tube of appropriate dimensions. The NOx sampler contains the same elements as the NO2 device, but it is also fitted with a chromic acid impregnated disc; this disc converts NO to NO2 which is then trapped by the triethanolamine along with preformed NO2. The trapped NO2 in all cases is determined as nitrite colorimetrically and NO is measured by difference between the NOx and NO2 values. The NOx sampler gives accurate and reproducible results if the chromic acid disc is in place for 24 hours or less; it is necessary, therefore, to insert and remove the disc within reasonably short times before and after sampling. We believe, however, that this operation will not be a serious problem for the user.

All diffusional samplers use the laws of gas diffusion as the basis for the assumption that there is no change in sampling efficiency due to changes in pressure. The objective of this study was to examine experimentally the effect of atmospheric pressure on the collection efficiency of a simple diffusional sampler. The results indicate that the sampler efficiency is actually dependent on atmospheric pressure, with a decrease in efficiency with each decrease in pressure. While this loss in efficiency would be very significant at great altitudes, the loss is less than 7% at 18 000 feet, which would include any altitude likely to be sampled in industrial hygienic practice. This makes a pressure correction unnecessary at or near the earth's surface, but the requirement for correction increases markedly as pressure is greatly reduced. It was also shown that, for a diffusion path of constant diameter, the shorter the path length, the greater the effect of pressure on collection efficiency.

A rapid air titration method for determining SO2 concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO2 for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data.

When nitrogen dioxide (NO2) samplers were exposed at several reduced pressures, it was found that the sampling rate was correspondingly decreased; that finding did not agree with accepted diffusional theory. When the experiments were repeated using water vapor as the gas and molecular sieve as the sorbent, the observed sampling rates were in very good agreement with diffusional theory. These findings demonstrated that the pressure effect was not common to all diffusional samplers and suggested that there might be an alternate explanation for the results with NO2-triethanolamine (TEA). The best possibility appeared to be the dehydration of TEA that takes place at reduced pressures. That this is a very significant factor was demonstrated by simultaneous exposure to identical concentrations of NO2 at 1 atm and 50% or 0% relative humidity. In dry air the sampling rate was equivalent to that found previously at about 1/10 atm. The earlier results can be satisfactorily explained as indirect rather than direct effects of reduced pressure.

Four stable laboratory mouse populations were established; each contained approximately 400 mice of both sexes and all ages postweaning living in a single cage, as well as neonates caged in separate nesting boxes with their dams. Two were used to determine the effects of continuous exposure to a dietary level of 100 ppm DDT while the other two served as controls. The results indicated a significant decrease (p < 0.05) in neonatal survival (lactation index) within 20 wk after the beginning of exposure to the toxicant in one of the exposed populations and by 30 wk in the other. This deleterious effect of the DDT continued through each succeeding generation. On the other hand, improved postweaning survival in DDT-fed mice was noted. Histological examination showed no tumors in test or control animals; other pathology was seen more frequently in control than in test animals.

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.

A simple mathematical model of the molecular basis for the function of a diffusional sampler for dilute mixtures of gaseous contaminants in supporting gases is presented. The model is based on the movement of single molecules of the contaminant between sections of a tubular diffusion path on a step-by-step basis; the length of the step and of each section of the tube are equal to the mean free path, λ, under the specified conditions. When the model is used, the coefficient of diffusion, D, can be calculated from λ and the average velocity, v, of the contaminant molecule. Both λ and v were calculated independently using equations which involved the minimum number of assumptions. The value of D so estimated was of the same order as that in the literature, differing by a factor of <2. It should be emphasized that the model represents a statistical, thermodynamic approach to understanding diffusional samplers, and its utility is independent of the means of estimating λ and v for specific gas pairs.

A field test of two sampling methods for the determination of NO2 concentration in air is reported. All samples were collected in an underground salt mine in which diesel equipment is operated. Although each method has its own advantages, both appear to be suitable for most industrial hygiene applications.