Bernard E. Saltzman

Measurements of airborne aflatoxins during the handling of contaminated corn

Sample of airborne dust generated the handling of aflatoxin-contaminated corn were collected and analyzed to assess potential exposures of farmers and other agricultural workers to these mycotoxins. Using high volume total dust samplers and a high volume Andersen sampler, downwind dust samples were collected on glass filter when contaminated corn was transferred by augers from a storage bin into a wagon and back into the storage bin. The aflatoxin B1 content of the 15 dust samples ranged from 12.5 to 204.3 ppb, with an average of 138 ppb; the aflatoxin B2 content ranged from 1.1 to 41.6 ppb, with an average of 24.6 ppb. The B1 and B2 levels of contamination in the bulk corn were 223.9 and 17.5 ppb, respectively. The gravimetric dust concentration in the air ranged from 7 mg/m3 to 417 mg/m3. The samples taken with an Andersen sampler indicate the dust is relatively coarse with only approximately 17% less than 7 micrometer. An analysis of the dust from each stage showed higher levels of aflatoxins in the larger first-stage particles than in the finer particles on the succeeding stages. The results of this study indicate that the dust generated when handling contaminated commodities also may be contaminated and represent a potential inhalation hazard. This fact, coupled with the extreme toxicity and carcinogenicity previously demonstrated in animal studies, suggests that appropriate measures be taken to prevent worker exposure during handling of contaminated materials.

Total body burdens and tissue concentrations of lead, cadmium, copper, zinc, and ash in 55 human cadavers.

Trace metal contents of human tissues and total body burdens are useful for studies of nutrition and certain diseases. Data are summarized and analyzed for individuals exposed to the normal Cincinnati environment, for 29 tissues from 55 cadavers for lead and ash concentrations, and from 26 cadavers for cadmium, copper, and zinc concentrations. Total body burdens also were calculated and correlated against each other and age. The distributions for ash, copper, and zinc were close to normal, but those for lead and cadmium were closer to lognormal. Bone lead increased with age, whereas soft tissue lead did not. The calculated mean percentage of total body lead in the bones ranged from 78% at age 20 to 96% at age 80. Correlations of blood concentrations with total body burdens were negligible for cadmium and zinc. For copper the correlation coefficient was a poor 0.54. For lead in blood vs soft tissue burden it was a very poor 0.37, and vs total body lead it was negligible. Thus the use of blood samples as a convenient clinical measure of body burdens for these metals may be of limited value. These and other findings provide a useful bank of information for health studies.

Design and performance of miniature cyclones for respirable aerosol sampling.

Fifteen miniature cyclone presamplers were studied, each with a different combination of one of 3 outlet lengths, 3 outer tube inside diameters, and 3 outer tube outside diameters. A single simple generalized equation with one constant for each cyclone accurately represented the effects of flow rate upon cut size for all 15, and also for 3 dual inlet stainless steel cyclones. Another single generalized equation accurately represented pressure drops for all. Normalized particle sizes for all 15 plotted as a single straight line from 5 to 80% efficiency when plotted on log probability paper. These equations should be useful for accurate design and prediction of performance of miniature cyclones.

The Determination of Fluoride in Urine Using a Fluoride-Specific Ion Electrode

A specific, economical, and fast method of analysis for fluoride in urine was developed which employs a fluoride-specific ion electrode. Former distillation or diffusion steps required for separation from interferences have been bypassed. A total ionic strength urinary buffer (TISUB) was formulated for this application.

Concentrations of six metals in the air of eight cities

During 1968-1971, 8763 samples were collected at 59 sites in US cities for a study of particulate lead concentrations in air. Each site was sampled continuously for a full year. These samples have been analyzed for total suspended particulate matter and for cadmium, chromium, lead, manganese, nickel, and zinc. Results of over 42,000 analyses are summarized in convenient graphical form, showing geometric means, geometric standard deviations, maxima, and minima. Supplementary tables present these data and cumulative frequency distributions. This historical data base should be a useful reference to determine effects of changes in fuel consumption patterns and trends. It presents a uniquely extensive cross-sectional picture of trace metal concentrations determined by a single highly experienced laboratory. Results were compared with available recent data for 17 identical sites. Recent lead concentrations averaged 35% of the older values, and some reductions occurred in concentrations of other metals.

Generalized Performance Characteristics of Miniature Cyclones for Atmospheric Particulate Sampling

Small cyclones are advantageous for size selective sampling of atmospheric particulate matter because they are capable of collecting large samples and are less subject than impactors to particle bounceoff and reentrainment. However, there has been a lack of an accurate generalized quantitative description of their performance, which has necessitated extensive calibrations of each design. Collection efficiency data for 30 cyclones have been accurately fitted by two simple equations using outlet Reynolds number as a variable rather than flow rates. They also fitted the limited available data for the effects of temperatures ranging from 25 to 204 °C. Normalized particle sizes plotted on log probability paper vs collection efficiency as a single straight line for all experimental flow rates. Three constants fully described the performance of each cyclone, and these constants could be estimated since they varied over a small range for most of the cyclones. The new generalized empirical equations should facilit...

Reproducibility and Quality Control in the Analysis of Biological Samples for Lead and Mercury

A simple statistical calculation was applied to 8 years of data on routine control sample and duplicate analyses from a laboratory quality control program. This provided standard deviations truly representative of this laboratory at no additional analytical expense, and accurate information on how they varied with concentrations. From these, the detection limit of the method, upper warning limits, and upper control limits for differences between duplicate analyses were calculated. These values were conveniently used for quality control in determinations of lead in blood and of mercury in urine.

Significance of Sampling Time in Air Monitoring

More efficient air sampling programs can be designed, and clearer interpretations of their data made, if important theoretical aspects are clearly understood. The choice of a sampling time is an important decision affecting the results. Empirical and theoretical calculations show that the averaging effect of sampling time attenuates responses to short period fluctuations in pollutant concentrations. Data for sulfur dioxide concentrations in six cities are examined. The body acts as a sampling mechanism also, and concentrations inside the body fluctuate less than those outside. These damping processes are quantitatively described. A significant biological parameter is the product of the biological half-life of a pollutant and the fraction of entrance to total resistance for its passage through the body. When sampling time is four times this parameter, attenuation of significant fluctuations is about the same in both samples and the body; when it is twice the parameter, the “sampling window” transmits all s...

Health risk assessment of fluctuating concentrations using lognormal models.

A mathematical model is proposed for assessing health risk rates of fluctuating concentrations. Each time-averaged concentration may be regarded as a dose that, when applied to the dose-response curve, produces a risk of an adverse effect. A theoretical derivation shows that the dose-response pattern is a cumulative lognormal curve because of the diversity of the individuals in the exposed population. Similarly, the concentration pattern is a log-normal distribution because of the diversity of emission sources and dispersive processes. The health risk is produced by the overlapping of the right tail of the concentration distribution and the left tail of the dose-response curve. The evaluation of the joint probability in this region has been performed by numerical integration by computer in terms of two generalized parameters. One represents the geometric standard deviation of the concentration distribution relative to that of the dose-response curve, and the other represents the distance between the geometric mean concentration and the concentration producing an adverse response in 50% of the exposed population. These results are presented graphically and in tabular form. If the two parameters of the dose-response curve are known, the health risk of the concentration pattern may be calculated conveniently for any geometric mean and geometric standard deviation values.

Linear Pharmacokinetic Models for Evaluating Unusual Work Schedules, Exposure Limits and Body Burdens of Pollutants

The adverse effects of workplace exposures to pollutants relate more accurately to the concentrations of pollutants in the body than in the environment. In many cases pharmacokinetic models may represent the external to internal concentration relationships with useful accuracy. Simplified equations are presented for stepwise calculations on a series of time-averaged, external concentrations to give a corresponding series of internal concentrations. Accurate results were obtained for averaging times not exceeding one-fourth of the biological half-life of the pollutant. A convenient measure of internal concentration is the external concentration that would be at in vivo equilibrium with it (termed biologically effective concentration). Three measures of damage burden are proposed, each appropriate for different toxic mechanisms. The calculations readily may be carried out on a programmable calculator or microcomputer. Illustrative examples show how unusual work schedules may be compared with an 8 hr/day, 5 days/week schedule and how appropriate short- and long-term exposure limits may be determined. Other examples, illustrated for lead, relate absorbed mass rates to body concentrations and body burdens in a two-compartment kinetic model. These calculations should provide a more accurate evaluation of fluctuating concentrations, which can be handled easily.