Biomedical subjects
Publications and source records attributed to L Ritter.
Authors report their case of Fournier's gangrene on the basis of their own observations and relying on data of the literature. Complete healing can be expected of immediate radical surgery and of aggressive intensive and antibiotic treatments.
No standard methods presently exist for measuring air and surface residues in indoor environments following pesticide applications. Four studies of chlorpyrifos broadcast applications for flea control were conducted to test preliminary sampling guidelines developed by Health and Welfare Canada. Air and wipe samples were collected for 24 hr following 0.5% or 0.48% chlopryifos applications. Ventilation from open doors or windows reduced air concentrations substantially. Air concentrations also varied with sampler height; i.e., greater near the floor than at one m above the floor. Wipe sampling from aluminum foil exhibited high precision (less than 10% coefficient of variation), and wipe sampling of carpets and other surfaces did not show variability in excess of the variability in initial pesticide deposits produced by the application procedures. Residues recovered from treated surfaces decreased by 60-70% over 24 hr, while residues on untreated surfaces increased 200-300% over this period. The Guidelines for Assessment of Indoor Occupant Exposure to Pesticides developed by Health and Welfare Canada have been revised in light of these findings, and provide a set of standard procedures for monitoring indoor air and surface residues. Further studies will be required to determine human exposures and health risks resulting from indoor pesticide applications.
A cohort study of the mortality experience (1971-1985) of male Saskatchewan farmers has been conducted. This study involved linkage of records of the almost 70,000 male farmers identified on the 1971 Census of Agriculture and the corresponding Census of Population to mortality records. Pesticide exposure indices for individual farm operators for the year 1970 were derived from the 1971 Census of Agriculture records. Although the cohort as a whole had no excess mortality for any specific causes of death, including non-Hodgkin's lymphoma, significant dose-response relationships were noted between risk of non-Hodgkin's lymphoma and acres sprayed in 1970 with herbicides, as well as with dollars spent on fuel and oil for farm purposes in 1970. Using Poisson regression modeling, we found that relative risks for the highest level of herbicide use (greater than or equal to 250 acres sprayed) and fuel purchased in 1970 (greater than or equal to $900) on farms less than 1,000 acres total area were 2.2 (95% confidence interval = 1.0-4.6) and 2.3 (95% confidence interval = 1.1-4.7), respectively.
Dermal absorption of the 14C-ring-labeled phenoxy herbicides 2,4-D [(2,4-dichlorophenoxy)acetic acid], 2,4-D amine (2,4-dichlorophenoxyacetic acid dimethylamine), 2,4-D isooctyl (2,4-dichlorophenoxyacetic acid isooctyl ester), and 2,4,5-T amine (2,4,5-trichlorophenoxyacetic acid trimethylamine) was examined following topical applications of the herbicides to the back of rabbits, the back and tail of rats, the forearm and forehead of rhesus monkeys, and the forehead of human volunteers. The effect of three pesticide vehicles (water, acetone, and Esteron LV96) was also investigated. The total percent dermal absorption was calculated from the mean percent urinary recoveries from the animal tests and corrected for nonurinary excretion of the radiolabel using data from intramuscular (im) injections. The human data are reported without im correction. The reliability of animal data for modelling human dermal absorption of pesticides is highlighted.
Various methods of preparing dermal application sites in Fischer 344 rats prior to exposure to 2,4-dichlorophenoxyacetic acid dimethylamine salt (2,4-D amine) and the effect of various cleansing agents following exposure were examined by measuring recoveries of 14C-labeled 2,4-D amine in skin, postapplication cleansing solution, blood, and urine. The middorsal area of the rat was the site of application for four treatments tested: (1) hair clipping only, (2) hair clipping followed by an epilatory cream, (3) hair clipping plus shaving with an electrical razor, and (4) as in treatment 3 followed by washing with soap and water. A last preparation was the rat's tail thoroughly brushed with soap and water. The results indicated that the tail retained greater than 75% of the material, thus preventing its absorption into the blood stream and subsequent removal by cleansing. With treatment 1 the dense short hair remaining after clipping impaired the absorption of 2,4-D as evidenced by considerably lower blood and urinary levels than treatments 2-4. With preparations 1-4, 45-61% of the dose was removed with the 7-h postapplication cleansing and a further 5-6% with the subsequent 23-h cleansing. In other studies using preparation 3 above, the following cleansing agents were tested: soap and water, water, isopropanol, acetone, and Rad-Con, a foam-producing cleanser. Rad-Con removed more 2,4-D from the skin than other cleansing agents after 7 h of exposure and more than soap and water after 23 h. The percentages of 2,4-D left on the skin following either 7- or 23-h cleansing with Rad-Con were 8-12%, nearly half those following the other cleansing agents. Cleansing agents other than Rad-Con presented little advantage over soap and water. With all cleansing agents, delaying cleansing from 7 to 23 h after exposure resulted in higher blood and urinary levels of 2,4-D measured 24 h after application.
The results of two methods of analysis for measuring glove permeability to pesticides are reported. The standard ASTM F739-85 testing procedure was used to determine breakthrough times and permeation rates for four protective glove materials for two commercially available pesticide formulations. The same glove materials and pesticides then were tested using an in-house developed automated in-vitro diffusion analysis (AIDA) procedure. The ASTM and AIDA procedures both demonstrated no detectable breakthrough of Sevin 50W or 2,4-D Amine 96% for nitrile butyl rubber and polyvinyl chloride gloves. Although no breakthrough of Sevin 50W or 2,4-D Amine 96 was detected for natural rubber or neoprene gloves following the ASTM procedure, permeation was observed in 2 of 3 replicate tests for both rubber and neoprene gloves when using the AIDA method. The observed discrepancy may have been caused by a longer sampling duration for the AIDA method (16 hr) than the ASTM procedure (8 hr). Advantages of the AIDA procedure are discussed.
Dermal absorption of the insecticide lindane (1 delta, 2 delta, 3 beta, 4 delta, 5 delta, 6 beta-hexachlorocyclohexane) was determined in rats and rhesus monkeys. Lindane is in widespread use as a 1% cream or lotion scabicide formulation and as a 1% miticide shampoo for body lice control in humans. Results obtained following our in vivo dermal absorption procedure demonstrated that 18 +/- 4.1%, 34 +/- 5.2%, and 54 +/- 26.3% of the applied dose was absorbed following topical applications at a rate of 1.5 micrograms/cm2 (6.2 micrograms/100 microliters of acetone) of the 14C-labeled pesticide to 4.2-cm2 regions of the forearm (n = 8), forehead (n = 7), and palm (n = 4) of rhesus monkeys, respectively. Dose sites were washed with soapy water 24 h posttreatment. Comparative studies in rats (n = 5) dosed middorsally demonstrated 31 +/- 9.5% absorption. Statistical analysis of the 14C excretion kinetics demonstrated slower clearance of lindane from rats than monkey forearm, forehead, or palm. Intramuscular (im) injections of 14C-lindane gave 52 +/- 7.1% recovery in monkey (n = 8) and 64 +/- 5.9% in rats (n = 5), suggesting body storage of this lipophilic chemical.
Dermal absorption of the insecticide lindane was determined following topical application of ring 14C-labeled lindane to the tail of Sprague-Dawley rats. The tail was tested as a practical alternative to the rat mid-dorsal (back) region, and the data obtained were compared to those with rat back and with those of rhesus monkeys in our previous reports. There was no significant difference between total percentage urinary 14C recovery for rats dosed on the tail with occlusive tail covers (52 +/- 6.2%; t1/2 = 2.7 d) compared to those with nonocclusive covers (55 +/- 4.4%; t1/2 = 2.9 d). Neither the total percentage urinary recovery nor the t1/2 values obtained for the rat tail and rat back models differed significantly. Carbon-14 activity was still detectable in urine samples taken after 72 d post-treatment. However, an extensive tissue analysis failed to demonstrate 14C activity persisting at 72 d, with the exception of trace levels detected in blood serum and tail tissue. Advantages of the rat tail model are highlighted.
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The case of a patient is reported, who developed a squamous cell cancer in a long standing anal fistula track. The observations seem to prove that irritated epithelium of chronic anal fistulas may be the source of a malignant disease.
Photomirex (8-monohydromirex) is a demonstrated environmental contaminant and was observed in previous short-term studies to produce lesions in the liver, thyroid and testes of male rats. The present study was undertaken to confirm those observations and to determine the effects after a longer period of exposure. Male rats were fed photomirex for 13 weeks at levels of 0.20, 1.0, 5.0, 25 and 125 ppm in the diet. Deaths were observed in animals receiving the highest dose. Decreased body weight gain and food intake were also observed in that group. Liver weights were increased at 5.0 ppm photomirex and higher. Photomirex caused changes in several biochemical parameters including serum sorbitol dehydrogenase and hepatic aniline hydroxylase activities. Dose-related histological abnormalities were observed in the thyroid and liver starting at the lowest dose level. These results confirm earlier findings and show that photomirex is a potent hepato- and thyrotoxin.
The hemostatic efficacy of ethamsylate studied by a matched-pair analysis was not proved to be statistically significant. The appearance of bleeding signs as well as the frequency of platelet transfusions have been examined. An important side-effect was found in patients receiving ethamsylate: severe leucocytopenia (less than 1000 leucocytes/microliters) was noticed more frequently followed by an enhanced susceptibility to infections. The incidence of septic infections was proved to be significantly increased in an extended sample of 100 patients.
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The present investigation involved an analysis of approximately 70,000 male Saskatchewan farm operators, a subset of the 365,000 Canadian farm operators to be investigated in the Canadian Farm Operator Mortality Study. The results of the Saskatchewan analysis indicate that during the interval studied, overall mortality among Saskatchewan farmers was 25% lower than that for all Saskatchewan men, and that, during the same time interval, the risk of death from all types of cancer was also about 25% lower among Saskatchewan farmers than to all Saskatchewan men. Although the present study indicates that overall mortality of death from cancer was 25% lower among Saskatchewan male farmers, there was a relationship between non-Hodgkin's lymphoma mortality and acres sprayed for weeds; a similar risk relationship between expenditures on fuel oil and risk of death from non-Hodgkin's lymphoma was also evident. The magnitude of risk for Saskatchewan farmers is probably greater than that reflected in the estimates in this study, due to the likelihood of misclassification of exposure. There is a particular need for further studies in this area to improve the quantification of farming-related exposures, and to study the exposure history of individuals who develop non-Hodgkin's lymphoma.