[Occupational reproduction epidemiology on the basis of the Danish National Birth Cohort. The Danish Society of Occupational Medicine].
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Biomedical subjects
Publications and source records attributed to Jens Peter E Bonde.
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Some people react to smells or chemicals at levels far below toxicological thresholds with nonspecific symptoms, fear and social isolation. They may be diagnosed with multiple chemical sensitivity. There is no empirical evidence indicating that this condition is explained by toxicological mechanisms, even though a number of theories have been proposed. The authors of this review conclude that this is a functional condition. These patients need information and treatment in accordance with this fact. Instead of being advised how to avoid exposure to chemicals, they should be properly trained in appropriate confrontation with the chemicals encountered in everyday life.
OBJECTIVES: Male psychologic stress can affect semen quality and couple fecundability. METHODS: We conducted a prospective study of 430 Danish couples who were trying to become pregnant for the first time. In each menstrual cycle, both partners filled out a 12-item version of the General Health Questionnaire (GHQ-12), an assessment of psychologic stress. A blood sample was drawn from both partners. The men collected a semen sample at enrollment and each month during follow up. RESULTS: Semen quality was not related to the man's GHQ score in either within-subject analyses or between-subject analyses. There were no consistent associations between stress and serum concentration of luteinizing hormone, follicle-stimulating hormone, inhibin B, testosterone, or estradiol. The pregnancy rate was 14% in cycles with an absolute GHQ-12 score in the highest quartile, compared with 18% in low-stress cycles. Odds of pregnancy decreased moderately with increasing score. The effect was confined to 77 men with a sperm density below 20 million/mL (adjusted odds ratio = 0.06; 95% confidence interval = 1.01-0.58 for highest distressed quartile vs. lowest distressed quartile in this low sperm density group). In within-subject analyses, cycle-specific changes in male stress did not change the odds of pregnancy. High absolute score was associated with a lower frequency of sexual intercourse, but adjustment for frequency had little effect. CONCLUSION: The effect of a man's daily life psychologic stress on his semen quality is small or nonexistent. Our results indicate an effect of stress only on fecundability, and this only among men with low sperm concentration.
BACKGROUND: Job strain, defined as high job demands and low job control, has not previously been explored as a possible determinant of male fertility. We collected prospective data on job strain among men, and describe the associations with semen quality and probability of conceiving a clinical pregnancy during a menstrual cycle. METHODS: Danish couples (N = 399) who were trying to become pregnant for the first time were followed for up to 6 menstrual periods. All men collected semen samples, and a blood sample was drawn from both partners. Job demand and job control were measured by a self-administered questionnaire at entry, and in each cycle the participants recorded changes in job control or job demand during the previous 30 days. RESULTS: In adjusted analyses, no associations were found between any semen characteristic or sexual hormones and any job strain variable. The odds for pregnancy were not associated with job strain. CONCLUSIONS: Psychologic job strain encountered in normal jobs in Denmark does not seem to affect male reproductive function.
BACKGROUND: Few studies relate the occurrence of shoulder disorders to quantified ergonomic exposures. This study evaluates the hypothesis that shoulder loads in repetitive work might contribute to the occurrence of shoulder tendinitis. METHODS: This is a cross-sectional study of 1961 workers in repetitive work and 782 referents. Shoulder loads were quantified at task level and measures of exposures were assigned based on task distribution. Symptoms in combination with clinical criteria defined shoulder tendinitis. RESULTS: The prevalence of shoulder tendinitis was higher among exposed workers (adjusted OR 3.1, 95% CI 1.3-3). Neither frequency of movements (ranging 1-36/min) nor lack of micro-pauses in shoulder flexion (ranging 0-100% of cyclus time) was related to disease prevalence. Increasing force requirements (categorized as light = 1, somewhat hard = 2, hard = 3 or very hard = 4) increased risk slightly (OR 1.6, 95% CI 1.0-2.6 per unit). CONCLUSIONS: The results indicate that workers with repetitive tasks have increased risk of shoulder tendinitis, which partially can be attributed to force requirements.
BACKGROUND: Scrotal temperature and semen quality have been found to be inversely correlated in several studies, and variation in scrotal temperature may contribute to the well known variation in semen quality. The reason for the variation in scrotal temperature is not well understood although determinants could be of a genetic nature. METHODS: We monitored scrotal skin temperature for 24 h in a group of monozygotic and dizygotic twins and single-born brothers (n = 48 males). A thermistor was attached to the underwear and the temperature of the scrotal skin was recorded every 5 min using a small portable data logger. RESULTS: A correlation in median scrotal temperature was found among monozygotic twins (r = 0.64, P = 0.01), but not in dizygotic twins and single-born brothers (r = 0.17, NS). Similar results were found for other percentiles of temperature. CONCLUSIONS: The results suggest a genetic component to the variation in scrotal temperature. An hereditary element in male fecundity may be expressed through scrotal temperature, which constitutes a mechanism independent of those responsible for the development of the sperm producing epithelium.