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Scrotal ultrasonography was performed in 888 testes of 444 randomly selected men appearing before the medical board prior to military service (Mili group, 287 men, median age 18.8 years), and in employees from an industrial company (Empl group, 157 men, median age 35.6 years). The ultrasonic volume of each testis was calculated from 3 perpendicular measurements. The ultrasonic texture on sectional planes was scored using a scale from 1 to 5, 1 being very regular, 2 slightly irregular, 3 moderately irregular, 4 very irregular or with bright echogenic points, and 5 with demarcated tumor suspicious areas. Orchidometer measurements were performed in 258 men in Mili group, and semen samples were obtained from 121 men in Empl group. The ultrasonic volume of the right testis (median 14.1 ml, range 3.0-31.4 ml) was bigger than that of the left testis (median 13.0 ml, range 3.5-35.2). The volume was dependent on age for men under 20 years, but not for men aged 20 years or more. The subgroup of men with a history of cryptorchidism had a smaller average testicular volume (median 10.5 ml) compared with men with normal descent (median 14.1 ml). Ultrasonic volume was positively correlated to the total sperm count in the ejaculate, to sperm penetration in egg white, and to normal sperm morphology. The echo score distribution showed slightly higher scores in Empl for both the right and the left testis. Men in Empl group were older, and it could not be precluded that this difference was due to age.(ABSTRACT TRUNCATED AT 250 WORDS)

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A biosurvey in the Danish metal industry measured the genotoxic exposure from stainless steel welding. The study comprised measurements of chromosomal aberrations (CA), sister-chromatid exchanges (SCE), unscheduled DNA synthesis (UDS) in peripheral lymphocytes and serum immunoglobulin G. Environmental monitoring of welding fumes and selected metal oxides, biomonitoring of chromium and nickel in serum and urine and mutagenic activity in urine, and evaluation of semen quality were also done. Manual metal arc (MMA) welding and tungsten inert gas (TIG) welding were the dominant welding processes. A higher frequency of chromosomal aberrations, classified as translocations, double minutes, exchanges and rings, was observed in stainless steel welders than in non-welders. SCE was lower in welders working with both MMA and TIG welding than in reference persons. N-Acetoxy-N-acetylaminofluorene (NA-AAF)-induced UDS was lower in 23 never-smoking welders than in 19 unexposed never-smokers. Smoking was a confounding factor resulting in significantly higher CA, SCE, NA-AAF binding to DNA and mutagenic activity in urine. Age was also a confounder: CA, SCE, NA-AAF binding to DNA and UDS increased significantly with age. No significant correlation between SCE and CA or between CA and UDS was found. UDS decreased significantly with increasing lymphocyte count and a higher lymphocyte count was seen in MMA welders than in reference persons and in smokers than in non-smokers. Differences in the composition among lymphocytes in exposed persons compared with non-exposed are suggested. MMA welding gave the highest exposure to chromium, an increased number of chromosomal aberrations and a decrease in SCE when compared with TIG welding. Consequently improvements in the occupational practice of stainless steel welding with MMA is recommended.

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Many new materials and processes are about to find their way from the research laboratory into industry. The present paper describes some of these processes and provides an overview of possible occupational hazards and a list of chemicals used or produced in the processes. The technological areas that are considered are metal surface treatment (ion implantation, physical and chemical vapor deposition, plasma spraying), powder metallurgy, advanced technical ceramics, and fiber-reinforced plastics.

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A comparison of semen parameters from 25 workers at a reinforced plastic production plant and from 46 age-matched male fertility patients was carried out. For a period of more than three months before the semen analyses, the 25 workers had been exposed to styrene and acetone in concentrations exceeding the Danish threshold limit values. Serum concentrations of follicle stimulating and luteinizing hormones, semen sample volume, and concentration of sperm showed no differences between the two groups. Significant differences between the two groups were found in the percentage of live sperm, immotile sperm, and normal sperm. The reinforced plastic plant workers showed, in terms of semen quality, better values in the percentages of live sperm and immotile sperm, whereas they had a reduced percentage of normally shaped sperm. It was found that the reinforced-plastic workers had increased percentages of the amorphous and the pyriform sperm head shapes as compared to the fertility clientele. In sperm midpiece and sperm tail defects, the two groups showed similar values. From the data it could be concluded that work with production of reinforced plastic might result in an increase in the number of abnormal sperm heads.

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Questionnaire studies of patients from fertility clinics suggest that welders may have an increased risk of reduced semen quality. In this study, welders and nonwelders from the same plants were asked to provide blood, urine, and semen samples. Urine was analyzed for chromium and nickel, and for mutagenic activity and metal concentration; blood for metal concentrations, immunoglobulin G, total protein, and measures of genotoxicity in lymphocytes; and semen was evaluated by standard semen analysis. Results of the semen evaluation, presented here, showed no difference in semen quality between welders and nonwelders. Because the metal dust exposure of nonwelders in the plant may be higher than that in the general population, welders were also compared to referents not working in the metal industry. Again, no decrease in semen quality associated with welding was demonstrated.

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Survivors of Bulinus truncatus from one exposure to niclosamide (Bayluscide) were used to establish the next generation in a five generation long laboratory selection for increased tolerance to niclosamide. In a comparison of the tolerance to the molluscicide between two original and two selected strains about 150 snails of each strain, divided into four size-groups, were exposed to aliquots of the same niclosamide solution on the same day and during the same time of the day. It was shown that five generations of relatively mild selection (30-50% survival) resulted in a significant increased tolerance to niclosamide in snails with only one exposure before start of the selection procedure. A comparison with published data indicated that the unselected strains did not change their tolerance to niclosamide during seven years of laboratory breeding. The strain exposed to niclosamide once in each of 16 generations showed an avoidance reaction to the chemical by crawling out of the water.

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Based on a study of one laboratory culture of each of the three species Bulinus forskalii, B. obtusispira and B. liratus it is shown that the two last mentioned species differ in enzyme mobility in seven out of eight enzymes investigated. It is pointed out, that, prior to using enzyme characters for identification purposes, a study of the intra- and interpopulation variation should be carried out. It is mentioned, that the difference in absolute mobility, the quality of the bands and the price for the enzyme stainings should be taken into consideration, when enzymes are used for identification of Bulinus species. For the specific problem of separating B. liratus and B. obtusispira it is suggested to study the intra- and interpopulation variation in the enzymes alpha-glycerophosphate dehydrogenase, phosphoglucose isomerase, hydroxybutyrate dehydrogenase and esterase-d with the aim of finding one or more enzymes usable for distinguishing these two, morphologically similar, species.

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The enzyme phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), hexokinase (HK), adenylate kinase (AK), fructokinase (FK), mannose-6-phosphate isomerase (MPI), glucose-6-phosphate dehydrogenase (G-6-PDH) and malate dehydrogenase (MDH) were chosen to study the variation between isolates, cercariae and adults, individuals, and sexes of Schistosoma mansoni and S. rodhaini, using horizontal polyacrylamide gel electrophoresis. The method described allows combinations of six of the eight enzymes to be scored in the homogenate from one adult worm. In adult S. mansoni one phenotype of the eight enzymes was observed in all isolates. In addition, the enzyme PGI showed polymorphism in the isolates from Tala, Kenya and Uganda. PGM in the isolates from Tala, Kenya and South Africa showed polymorphism. The cercarial phenotype differs from the adult phenotype in G-6-PDH, where the cercarial enzyme mobility is slower than that in the adult worm. The low amount of intrastrain variation observed in this species is explained by the limited amount of material used to establish the laboratory stocks, whereas the genetic similarity between geographically widely separated stocks does suggest that only limited geographical variation is likely to occur in S. mansoni. It is suggested that the gene controlling the PGI polymorphism is located on the sex chromosomes of S. mansoni. Mobility differences were observed between S. mansoni and S. rodhaini in the enzyme PGI and PGM, and these characteristics might be useful for a quick identification of schistosome cercariae emerging from Biomphalaria sp. in Africa.U

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A major factor in the geographical distribution of endemic schistosomiasis in Kenya is the discontinuous distribution of intermediate hosts. Biomphalaria pfeifferi is the main transmitter of S. mansoni and is found in the altitude zone 300-2,300 m; its absence from the costal region results in the absence of endemic schistosomiasis mansoni amongst the large human population in the coastal region. Snails belonging to the Bulinus africanus group appear to be responsible for all transmission of S. haematobium; they occur from near sea-level to an altitude of about 1,800 but are discontinuously distributed. There appears to be considerable potential for increase in the areas in which each form of schistosomiasis is endemic, taking into account existing patterns of snail distribution and likely developments in irrigation and water conservation. New localities reported here considerably extend the known distribution in western Kenya of B. truncatus, which could serve as an effective intermediate host for S. haematobium if a suitable strain were to become established in Kenya.

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