PubMed Health⌕ Search

Biomedical subjects

S B Larsen

Publications and source records attributed to S B Larsen.

At least 19 recordsLinked to original sources
PubMed1999

[Pesticides and time to pregnancy among Danish farmers].

The aim of this study was to examine time to pregnancy among farmers who used pesticides (traditional farmers) and farmers who did not (organic farmers). A total of 904 men, selected from the Danish Ministry of Agriculture lists of traditional and organic farmers, participated in telephone interviews. The participation rate was 84%. Information was collected on "time to pregnancy" for the youngest child, exposure to pesticides and potential confounders. Using the discrete analogue of the Cox Regression Model (including potential confounders: male and female smoking, female age, parity and contraceptive method), the fecundability ratio between traditional farmers using pesticides and organic farmers was 1.03 (95% CI: 0.75-1.40). In the group of farmers who sprayed with pesticides, none of the characteristics related to the use of pesticides could account for the variation in time to pregnancy. No overall effect of pesticides on male fecundability could be demonstrated in this retrospective study among Danish farmers.

Adult↗
PubMed1999

Effects of pesticide exposure on time to pregnancy: results of a multicenter study in France and Denmark. ASCLEPIOS Study Group.

The aim of this study was to determine whether there was a relation between male exposure to pesticides and the amount of time needed to conceive (time to pregnancy) for farmers and agricultural workers in France and Denmark. The authors used retrospective studies to compare the time to pregnancy of couples in which the man was exposed to pesticides during the year before the birth of their youngest child with that of couples in which the man was not exposed. In 1995 and 1996, the authors studied 362 French rural workers (142 exposed to pesticides and 220 not exposed), 449 Danish farmers (326 conventional farmers exposed to pesticides and 123 nonexposed organic farmers), and 121 Danish greenhouse workers exposed to pesticides. The fecundability ratio for exposure to pesticides (Cox model, before and after adjustment for confounding factors) did not differ from 1 in any of the three populations. In France, the adjusted fecundability ratio was 1.17 (95% confidence interval (CI) 0.89-1.55) for exposed and nonexposed agricultural workers. In Denmark, it was 1.09 (95% CI 0.82-1.43) for exposed and nonexposed farmers and 0.83 (95% CI 0.69-1.18) for greenhouse workers and nonexposed farmers. Thus, this study found no relation between fertility (time to pregnancy) and male exposure to pesticides.

Adult↗
PubMed1999

Aneuploidy in sperm and exposure to fungicides and lifestyle factors. ASCLEPIOS. A European Concerted Action on Occupational Hazards to Male Reproductive Capability.

Fungicides include chemicals that are known aneugens. The purpose of the present study was to investigate whether occupational exposure to these and other agricultural pesticides induces aneuploidy in human sperm. The contribution of lifestyle factors (smoking and alcohol consumption) to the frequency of aneuploid sperm was evaluated as well. The effects of age and sperm concentration were analyzed as confounders. Spermatozoa from 30 healthy farmers were studied before and after exposure to fungicides, using fluorescence in situ hybridization (FISH). Ten thousand spermatozoa were scored per semen sample to determine the disomy and diploidy frequencies for chromosomes 1 and 7. Exposure to fungicides was not associated with sperm aneuploidy. Smoking was significantly associated with sperm carrying an extra chromosome 1 and with diploid sperm as well as with the aggregate frequency of aneuploid sperm. Alcohol consumption, sperm concentration, and age showed inconsistent results before and after the season of exposure to fungicides. For low-level exposures, such as occupational exposures, the sensitivity of the sperm-FISH method may not be sufficient. The present study supports earlier ones showing that smoking can increase aneuploidy in human sperm.

Adult↗
PubMed1999

Human semen quality in relation to dietary pesticide exposure and organic diet.

The objective of the study was to corroborate or refute the hypothesis that farmers having a high intake of organic grown commodities have a high semen quality due to their expected lower level of dietary pesticides intake. Food frequency data and semen were collected from 256 farmers (171 traditional farmers and 85 organic farmers, overall participation rate: 32%) who were selected from central registers. Each farmer delivered one semen sample before the spraying season started. The farmers were divided into three groups where the commodities from organic production contributed no (N, 0%), medium (M, 1-49%), or a high (H, 50-100%) proportion of the fruit and vegetables consumed. Farmers having a high relative intake of organically grown fruit and vegetables also had a high relative consumption of organically produced meat, milk, and bread, and differences were observed comparing the actual mean intake of single commodities, such as rice, potato, and pork meat. The current individual dietary intake of 40 pesticides was estimated using food frequencies and generalized serving size data in combination with data on pesticide concentrations in food commodities as obtained from the National Danish Food Monitoring Program. The estimated pesticide intake was significantly lower among farmers of group H, but for all three groups of farmers the average dietary intake of 40 pesticides was at or below 1% of the acceptable daily intake (ADI) except for the dithiocarbamates (max = 0.21 microg/kg day = 2.2% ADI), methidathion, (max = 0.01 microg/kg day = 1.4% ADI), and 2-phenylphenol (max = 0.21 microg/kg day = 1.1% ADI). The median sperm concentration for the three groups of farmers was not significantly different (p = 0.40, median sperm concentration was N = 62, M = 44, and H = 75 million/ml). The group of men without organic food intake had a significant lower proportion of morphologically normal spermatozoa, but in relation to 14 other semen parameters no significant differences were found between the groups. Intake of 40 individual pesticides was correlated with four semen parameters (concentration, percentage dead spermatozoa, percentage normal sperm heads, and motility [VCL]). Five significant correlations (p value 0.01) were found among the 160 comparisons in relation to percentage dead spermatozoa: azinphos-methyl, carbaryl, chlorfenson, fenitrothion, and tetradifon. For all of them a lower percentage of dead spermatozoa were found in the groups with a high dietary intake of the specific pesticide. In contrast, for all pesticides evaluated only minor differences were found between the groups when considering spermatozoa concentration, morphology, and motility. In conclusion, the estimated dietary intake of 40 pesticides did not entail a risk of impaired semen quality, but precautions should be taken when generalizing this negative result to populations with a higher dietary exposure level or an intake of other groups of pesticides.

Adult↗
PubMed1999

Semen quality and sex hormones among organic and traditional Danish farmers. ASCLEPIOS Study Group.

OBJECTIVES: To confirm or refute the hypothesis that organic farmers have higher sperm concentrations than traditional farmers. METHODS: Traditional and organic farmers were selected randomly from central registers, and 171 traditional farmers and 85 organic farmers delivered one semen sample before the start of the spraying season. The participation rate was 28.8% among traditional farmers and 42.9% among organic farmers. RESULTS: The median sperm concentration for traditional and organic farmers was 58 million/ml and 64 million/ml, respectively. After adjustment for several confounders, sperm concentration, total count, proportion of non-vital spermatozoa, sperm chromatin structure, and motility variables did not differ significantly between the two groups. The traditional farmers had a significantly lower proportion of normal spermatozoa, but this result was not confirmed in a second sample. Organic farmers had slightly higher inhibin B concentration and testosterone/sex hormone binding globulin ratio. CONCLUSION: Despite slight differences in concentrations of reproductive hormones, no significant differences in conventional measures of semen quality were found between organic and traditional farmers.

Adult↗
PubMed1999

Environmental semen studies--is infertility increased by a decline in sperm count?

The objective of the studies was to evaluate infertility according to sperm count shifts. The distribution of the sperm count of 1024 Danish men (median 56 million/ml) served as reference. The data were transformed with multiplicative or additive models to create alternative distributions with median sperm count values changed by 25-100%. Sperm-count-specific fecundabilities were provided from a follow-up of first-pregnancy planners in a Danish population. The estimated average fecundability of the 1024 Danish men was 16.9% [95% confidence interval (95% CI) 16.7-17.2], and the proportion of cohabiting men with spouses pregnant within 1 year was 86.0% (95% CI 84.1-87.8). Simulations of alternative sperm count distributions indicated that the relationship between sperm count shift and fertility strongly depends on the median level of the sperm count at onset and the type of shift, a dramatic decline from a high level in a multiplicative model indicating a marginal change and a minor decline from a low level in an additive model representing a strong decrease in fertility. In some cases sperm count, therefore, may be an early warning of changes in fertility.

Adult↗
PubMed1999

Change in semen quality and sperm chromatin structure following occupational styrene exposure. ASCLEPIOS.

OBJECTIVES: Organic solvents have been suspected to exert detrimental effects on human spermiogenesis. Styrene, which is both mutagenic and neurotoxic, was selected as a suitable organic solvent for further assessment of a possible effect on semen quality and sperm DNA damage. SUBJECTS AND METHODS: Semen samples were collected from 23 reinforced plastics workers at the time of employment and after 6 months of styrene exposure and from 21 nonexposed farmers. Intra-individual changes in conventional semen parameters and sperm-DNA denaturation patterns were related to the internal dose of styrene exposure as measured by postshift urinary mandelic acid. RESULTS: A statistically significant decline in sperm density was seen during styrene exposure from 63.5 to 46.0 million sperm/ml, whereas no decline was seen in the nonexposed subjects. The total sperm count was almost halved from an initial value of 175 million sperm/ejaculate. However, no relationship was apparent when the sperm parameters were related to internal levels of exposure. However, an exposure-response relationship was shown for DNA-denaturation patterns, but the numbers were small. CONCLUSION: A declining sperm count following styrene exposure is suggested. However, the findings of the internal and external comparisons are inconsistent, and this may be due to the high intraindividual variability of semen parameters and the limited study size but may also be attributable to a weak internal exposure gradient. Spermatogenesis may be vulnerable to styrene exposure. However, due to the small numbers these findings are only preliminary.

Adult↗
PubMed1998

Selection bias in occupational sperm studies.

Participation rates in sperm studies are typically 25-50%, and therefore it is a matter of concern whether the men who provide semen samples truly reflect the parent population. The authors analyzed data from three Danish occupational sperm studies and evaluated the relation between age and occurrence of subfertility to participation and provision of semen samples. Age and subfertility were found to be rather strong determinants of participation. Willingness to provide semen samples was greater among men aged <40 years (odds ratio (OR) = 1.8, 95% confidence interval (CI) 1.3-2.6) and among men who had experienced an infertile period (OR = 1.7, 95% CI 1.3-2.1). Furthermore, the effect of infertility was modified by occupational exposure status, thus resulting in a tendency to differential selection and possibly biased risk estimates. In a cross-sectional study, the authors recommend that priority be given to a high participation rate and that data on the basic variables be collected from the entire study population, so that it is possible to make a nonresponder analysis and evaluate bias. Such an analysis can be carried out by means of questions enquiring about infertility, genital disorders, and earlier seminal examinations. Although the longitudinal study design is without many of the limitations of the cross-sectional study, a longitudinal study is usually not feasible.

Adolescent↗
PubMed1998

A follow-up study of semen quality and fertility in men with varicocele testis and in control subjects.

OBJECTIVE: To evaluate semen quality and fecundity in a group of men with initially untreated varicocele testis, in comparison with control subjects. PATIENTS, SUBJECTS AND METHODS: In a prospective, longitudinal study, 77 men (39 with varicocele and 38 control subjects) were evaluated in 1989 and re-investigated after 8 years. Fifty-seven men (29 with varicocele, 28 controls) were available for evaluation and they all completed a questionnaire. Semen from a total of 46 men (24 with varicocele) was compared with findings in 22 men from the control group. RESULTS: There was a decline in sperm count in the control group from 80 x 10(6)/mL to 55 x 10(6)/mL over the 8-year period, but nearly no change in the sperm count in the men with varicocele. The withdrawal rate from each group was the same and included both men with and without reduced semen quality. There were no differences between the groups in sperm motility values (straight-line velocity, curvilinear velocity) evaluated using computer-assisted semen analysis. Paternity was achieved by 10 of 14 men in the varicocele group, compared with 14 of 16 in the control group. CONCLUSIONS: There was no evidence that varicocelectomy might benefit patients, because the sperm concentration did not decline among men with varicocele over time. Computer-assisted semen analysis provided a good assessment of various sperm motility characteristics and we recommend evaluation using such objective methods, to allow comparison among studies

Adult↗
PubMed1998

The applicability of the flow cytometric sperm chromatin structure assay in epidemiological studies. Asclepios.

The impact of demographic, lifestyle, and seminal factors on the sperm chromatin structure assay (SCSA) parameters was evaluated in a population of 277 healthy Danish men. This cohort was established within the framework of a European Concerted Action on occupational hazards to male reproductive capability in order to examine the possible reproductive effects of exposure to styrene or pesticides. The SCSA measures the susceptibility of sperm DNA to in-situ acid-induced denaturation, by multiparameter flow cytometric analysis after staining with the DNA-specific fluorescent dye acridine orange. The green versus red bivariate cytogram patterns were quite variable among donors, showing a wide heterogeneity of sperm DNA denaturability. Nevertheless, in those cases where we had the possibility to measure two semen samples from the same donor, the cytogram pattern remained stable over time (0.64 < r < 0.78). Analysis of variance demonstrated that the SCSA results can be influenced by the age of the donor (P < 0.0001), smoking habits (P < 0.05), the presence of leukocytes and immature germ forms in the ejaculate (P < 0.0001), and the duration of sexual abstinence (P < 0.0001). Furthermore, the relationship between the SCSA data and sperm concentration, morphology, and vitality was weak (-0.22 < r < -0.46). Therefore, the SCSA provides independent and complementary measurements of semen quality and is thus a useful tool for epidemiological studies, but the effects of some confounders should be accounted for in the survey design and analysis.

Adolescent↗
PubMed1998

Time to pregnancy and exposure to pesticides in Danish farmers. ASCLEPIOS Study Group.

OBJECTIVE: Circumstantial evidence suggests that organic farmers may have higher sperm count than other men, but comprehensive epidemiological studies of male fecundity among farmers have never been carried out. A substantial increase of sperm count is expected to translate into a shorter time to pregnancy--the number of menstrual cycles or months it takes a couple to get pregnant from discontinuation of birth control. Toxicological effects on spermatogenesis in humans and animals have been described after exposure to several pesticides. The aim of this study was to examine time to pregnancy among farmers who used pesticides (traditional farmers) and farmers who did not (organic farmers). METHODS: A total of 904 (84%) men, selected from the Danish Ministry of Agriculture lists of traditional and organic farmers, participated in telephone interviews. Information was collected on time to pregnancy for the youngest child, exposure to pesticides, and potential confounders. RESULTS: With the discrete analogue of the Cox regression model (including potential confounders: male and female smoking, female age, parity, and contraceptive method), the fecundability ratio between traditional farmers who used pesticides and organic farmers was 1.03 (95% confidence interval (95% CI) 0.75 to 1.40). In the group of farmers who sprayed with pesticides, none of the characteristics related to the use of pesticides could account for the variation in time to pregnancy. CONCLUSIONS: No overall effect of pesticides on male fecundability was found in this retrospective study among Danish farmers. Also, we found no evidence of higher male fecundability in organic farmers.

Adolescent↗
PubMed1997

[Age at menarche and first sexual intercourse. A cross-sectional study of 17-year old Danish women].

The age at menarche and first intercourse was analyzed from data obtained from a questionnaire sent to 1500 17 year-old randomly selected Danish women (76% responded). The average age at menarche was 13.37 years (SD: 1.24). The median age at the time of the first intercourse was 16.6 years. Late sexual debut was observed for girls who were relatively old at menarche and for those with a higher level of education. Apparently the age at menarche and at first sexual intercourse has not changed significantly in recent years.

Adolescent↗
PubMed1995

[The first gynecologic examination. Indications, age and place].

The purpose was to investigate age, place, and indication for 17 year-old women's first pelvic examination. A postal questionnaire was sent to 1500 randomly selected 17 years-old Danish women. The response rate was 76%. The median age at which such examinations first took place was 17 years and 10 months. The majority (86%) of examinations were performed by general practitioners and 72% were performed in relation to prescription of oral contraceptives. This indication has previously been a recommendation of the Danish National Board of Health, but changes have been announced, and indications for pelvic examinations of teenagers should be discussed.

Adolescent↗
PubMed1995

Experiences of the first pelvic examination in a random samples of Danish teenagers.

OBJECTIVE: To describe Danish teenagers' experiences and preferences concerning the first pelvic examination. METHODS: Cross-sectional postal questionnaire study. A total of 1500 women, aged 17 years, were selected at random among all Danish women of that age. The response rate was 76%, and 551 had experienced their first examination. RESULTS: Thirty-two percent gave a negative general evaluation of the examination, and 13% found the examination very painful. The negative evaluation was strongly associated with the experience of pain, embarrassment, perceived impossibility of interrupting the examination, not knowing what the doctor was doing, learning nothing during the examination, indications other than oral contraception, and feeling of insufficient knowledge when arriving for the first examination. CONCLUSION: It is recommended that teenagers are given more information and realistic expectations prior to the first pelvic examination.

Adolescent↗