Mutagenicity of urine from greenhouse workers.

The mutagenicity of urine from spray applicators in 12 greenhouses in 1986 has been evaluated. The workers served as their own controls. Urine samples reflecting pesticide exposure were collected at the end of the day of application and a corresponding control sample was collected 3 d later. Using Salmonella typhimurium bacterial tester strains TA98 and TA100 with and without S9 activation, seven workers showed no significant differences (p less than 0.05) in the mutagenicity of their exposed and control urine. Of the five remaining workers, three, who wore no respirators, showed significantly higher (p less than 0.05) concentrations of mutagens in their exposed urine sample as compared to their respective controls. The mutagenicity of certain of the compounds applied by these latter workers is discussed.

Health among municipal sewage and water treatment workers.

Municipal sewage treatment plant workers are potentially exposed to a multitude of industrial chemicals and pathogenic microorganisms. A questionnaire survey of working habits, lifestyle and symptoms of illness was conducted among 189 municipal sewage treatment plant workers processing between three and ten million gallons of wastewater daily in 16 plants in New York State between March and July of 1984. Water treatment plant workers in the same cities comprised the comparison group. Sewage workers reported a significantly higher frequency of headache, dizziness, sore throat, skin irritation and diarrhea within the month immediately preceding receipt of the questionnaire, after controlling for various possible confounders. Eye and skin irritation were significantly associated with exposure to mutagens. The health significance of these findings and possible sources of error in assessing risk are discussed.

An introduction to the use of epidemiologic research methods in dairy science.

Many dairy scientists are not familiar with epidemiologic study designs and measures. The various designs (cross-sectional, case-control, cohort) are reviewed with special reference to their strengths and weaknesses. Epidemiologic measures (incidence and prevalence rates, relative risk, odds ratio, attributable fraction, and population attributable fraction) are defined, and their validity in the contexts of the different study designs is discussed. Incidence rate (risk of disease) is the number of new cases of a disease divided by the population at risk during a specified time period. Prevalence rate is the frequency of both new and old cases in a population at a specified point or period in time divided by the average population during that same period. Both incidence and duration of disease contribute to prevalence. Odds ratios and relative risks are measures of association (how much disease the exposed group experienced relative to the nonexposed group) and are used to assess the relative importance of risk factors. Attributable fraction is the proportion of the incidence in the exposed group that can be attributed to the specific exposure. Population attributuable fraction is the expected reduction in incidence in the whole population if the specific exposure were prevented. The attributable fractions are useful in planning preventive and herd health programs.

Urinary mutagens in municipal sewage workers and water treatment workers.

In view of the potential exposure of sewage treatment workers to a multitude of mutagenic substances, the frequency of urinary mutagens was measured by the Ames test among a sample of 164 sewage treatment workers employed in 14 sewage treatment plants which processed between 3 and 10 million gallons of sewage daily in New York State between March and July, 1984. The frequency was compared to that observed in 72 water treatment employees in the same municipalities. Sewage workers had a significantly higher risk for urinary mutagens after controlling for smoking, using the Ames test, both with and without the addition of the liver microsomal homogenate, S-9. More precise methods of measuring exposure in epidemiologic studies, particularly in environmental and occupational epidemiology, are in various stages of development. The application of one of these methods, the Ames test, to an occupational group (sewage workers) with potentially high exposure to mutagenic substances is described and the strengths and limitations of this application are discussed.

Toxic and protective constituents in pet foods.

An analytical survey of mutagens, nitrosamines, polychlorinated biphenyls, toxic elements, and gamma-emission, as well as the toxicologically protective constituents zinc, selenium, and vitamin C, in 48 pet foods was conducted. Aside from high concentrations of fluoride and iodide in some samples and the expectedly higher concentrations of mercury and selenium in certain cat foods containing fish, the samples were notably free of the other toxic constituents. Direct-acting and promutagens and nitrosamines were not detectable in any of the samples. gamma-Emission was very low in all of the foods. Polychlorinated biphenyls were only detected in one cat food.

External transcutaneous pacemaker for profound bradycardia associated with spinal cord trauma.

The successful use of external transthoracic pacing is described in a case of spinal cord trauma with profound bradycardia. This modality achieved blood pressures equal to transvenous pacing. In patients in whom venous access is difficult or represents a risk of infection, transthoracic pacing may offer a worthwhile alternative.

Toxicologic studies associated with the agricultural use of municipal sewage sludge and health effects among sewage treatment plant workers.

The proposed use of municipal sewage sludges as soil amendments on agricultural land involves potential health risks. Sludges may contain toxic heavy metals, synthetic organics, and pathogens. Studies of animals inhabiting sludge-amended soils, or foraging on crops grown on such soils, have shown an increased deposition of cadmium and polychlorinated biphenyls in animal tissues, hepatic microsomal enzyme induction, altered blood profiles, appearance of mutagens in blood and excreta, and lowered feed intake, feed efficiency, and milk production. Epidemiologic evidence of possible adverse health effects among sewage plant workers exposed to aerosolized pathogens or synthetic organic vapors during wastewater treatment or land spreading of sludge is still inconclusive. Other possible deleterious environmental effects include pollution of groundwater and toxicity to birds consuming worms or insects inhabiting sludge-treated soils.

Defining and measuring exposure in epidemiologic studies of potential zoonoses.

Articles suggesting the zoonotic potential of certain human diseases (eg, multiple sclerosis, rheumatoid arthritis, and leukemia) periodically appear in the literature and frequently receive considerable attention in the popular press. Although various epidemiologic study designs have been utilized to test these hypotheses, defining and accurately measuring animal exposure has been a problem common to most of these studies and in some instances has limited their usefulness. The relative strengths and limitations of the definitions and measurements used most commonly by investigators evaluating potential zoonoses are discussed. In addition, several recommendations for assessing animal exposure in future studies are made.

An alternative to routine operative cholangiography.

The use of the Fogarty biliary balloon catheter has added to the safety of common duct exploration. Review of our own series seems to support this concept. With this adjunct adn a careful anatomic dissection of the biliary system, one can decide to do cholangiography or common duct exploration based on carefully considered clinical factors when stones are suspected. Perhaps neither need to be done in many instances. Without trying to question the virtures of operative cholangiography, we believe that it can be used selectively rather than routinely.