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H A Kolstad

Publications and source records attributed to H A Kolstad.

At least 19 recordsLinked to original sources
PubMed2004

Surveillance of noise exposure in the Danish workplace: a baseline survey.

AIMS: To evaluate an epidemiological approach to a national noise hazard surveillance strategy, and report current exposure levels in the Danish workplace. METHODS: A study base of 840 companies in 10 selected high risk industries in the largest county in Denmark was identified from a national register. Noise exposure was measured among manual workers recruited from a random sample of workplaces in each industry. For reference, financial companies and a sample of residents were investigated according to the same protocol. The A-weighted equivalent sound level (L(Aeq)) for a full shift was measured by portable dosimeters worn by 830 workers employed at 91 workplaces (67% of 136 eligible companies). RESULTS: The epidemiological design proved feasible and established a baseline for future noise surveillance. Substantial resources were needed to motivate workplaces to enlist and the final participation rate was less than optimal (66.9%). The L(Aeq (8)) values in the selected industries were highly elevated (mean 83.7 dB(A) (95% CI 83.3 to 84.1) in comparison with residents and office workers (mean 69.9 dB(A), 95% CI 68.8 to 71.0). Some 50% of the workers were exposed to more than 85 dB(A) and some 20% to more than 90 dB(A) in several industries. CONCLUSION: Noise levels in Danish high risk industries remain high. A substantial proportion of workers are exposed to noise levels above the current threshold limit of 85 dB(A). Ongoing surveillance of noise exposure using full shift dosimetry of workers in random samples of workplaces most at risk to high noise levels may help reinforce preventive measures. Such a programme would benefit from compulsory workplace participation.

Adult↗
PubMed2001

[Audiometric surveillance of occupational environment].

Noise levels in Danish workplaces at which hearing impairment will occur in more than 10% of the workers are still frequent. Annually 300 cases are compensated for noise induced hearing loss at a national level. This may indicate that the current national hearing protection strategy, which relies on noise reduction only, is insufficient. By audiometric screening early hearing loss will be detected and further progression may be halted. This paper reviews the methods of continuous audiometric screening of noise exposed worker populations. Reliability and validity are discussed, and an overview of quality assurance programmes is given. It is concluded that a national hearing conservation program should be implemented in Denmark.

Audiometry↗
PubMed2001

Medical risk factors for small-bowel adenocarcinoma with focus on Crohn disease: a European population-based case-control study.

BACKGROUND: Crohn disease and biliary diseases have been associated with small-bowel adenocarcinoma (SBA). We examined how medical conditions affect the risk of SBA. METHODS: A population-based European multicentre case-control study during the period 1995-97 including 95 histologically verified cases of SBA along with 3335 population controls; 70 cases (74%) and 2070 (62%) controls were interviewed about previous medical conditions. RESULTS: Crohn disease was identified in two SBA cases (both located in ileum) and two controls; odds ratio (OR) 53.6 (6.0-477) (95% CI in parentheses). Only one case and no controls had had long-standing Crohn disease. Coeliac disease was associated with SBA (2 cases, 0 controls), but one of the cases was diagnosed at the same time as the SBA. Overall, people with a history of gallstones had no increased risk of SBA. The OR was exclusively increased during the 3-year period preceding the SBA diagnosis. Previous gallstone surgery, which may be a sign of severe gallstone disease, was not associated with SBA. Liver cirrhosis, hepatitis or medical treatments with radioactive substances or corticosteroid tablets were not associated with this disease. Cases with SBA had an increased prevalence of anaemia; OR 15.3 (2.5-92.1). An association between low educational level and SBA was found; OR 1.75 (1.0-3.0). CONCLUSION: This study supports Crohn disease and coeliac disease being strong but rare risk factors for SBA. Previous gallstones were unrelated to SBA, and detection bias may account for the findings in earlier studies.

Adenocarcinoma↗
PubMed2000

[Stress and fertility. A follow-up study among couples planning the first pregnancy].

Mental distress has often been suggested as a cause of unexplained infertility. However, the causal direction may well be from infertility to distress, and prospective data are needed. We therefore followed 393 couples, who were planning their first pregnancy, with prospective collection of information on distress from termination of birth control until pregnancy for a maximum of six menstrual cycles. The analyses included 1,475 menstrual cycles, and mental distress was measured in each cycle by the General Health Questionnaire (GHQ). Urine samples from each period of vaginal bleeding were analyzed for human chorionic gonadotrophic hormone, indicating early embryonal loss. We found that for cycles with the highest distress score (GHQ score above the 80 percentile) the probability of conception per cycle was 12.8% compared to 16.5% in other cycles (adjusted OR 0.6; 95% CI 0.4-1.0). The effect of distress was almost exclusively found among women with long menstrual cycles (OR 0.1; 95% CI 0.01-0.4 and OR 0.9; 0.5-1.4 for women with cycles > or = 35 and < 35 days, respectively). An increased incidence of early embryonal loss was also found among highly distressed women with long cycles, but was based on a small number of observations. It is concluded that psychological distress may be a risk factor for reduced fertility in women with long menstrual cycles.

Adult↗
PubMed2000

Sperm chromatin damage impairs human fertility. The Danish First Pregnancy Planner Study Team.

OBJECTIVE: To examine the relationship between sperm chromatin defects, evaluated by the flow cytometric (FCM) sperm chromatin structure assay (SCSA), and the probability of a pregnancy in a menstrual cycle (fecundability). DESIGN: Follow-up study. SETTING: The Section of Toxicology and Biomedical Sciences, ENEA Casaccia, Rome, Italy, and the Department of Occupational Medicine, Aarhus University Hospital, Aarhus, Denmark. PATIENT(S): Two hundred fifteen Danish first pregnancy planners with no previous knowledge of their fertility capability. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Semen samples were collected at enrollment to measure semen volume, sperm concentration, motility, and morphology (by microscopy), as well as chromatin susceptibility to in situ, acid-induced partial denaturation by the FCM SCSA. Time to pregnancy was evaluated during a 2-year follow-up period. Demographic, medical, reproductive, occupational, and lifestyle data were collected by questionnaire. Fecundability was correlated with SCSA-derived parameters. RESULT(S): Fecundability declines as a function of the percentage of sperm with abnormal chromatin and becomes small when aberrant cells are >40%. CONCLUSION(S): Optimal sperm chromatin packaging seems necessary for full expression of the male fertility potential. The SCSA emerged as a predictor of the probability to conceive in this population-based study.

Chromatin↗
PubMed2000

Is there an association between alcohol intake or smoking and small bowel adenocarcinoma? Results from a European multi-center case-control study.

OBJECTIVE: To discover whether tobacco smoking and intake of different types of alcoholic drinks are associated with small bowel adenocarcinoma (SBA). METHODS: A population-based European multi-center case-control study was conducted from 1995 to 1997. RESULTS: After a histological review using uniform diagnostic criteria, 47 (33%) of the 142 identified cases of SBA were excluded due to reclassification as either tumors of the papilla of Vater (n = 22), stromal tumors, or metastases; 95 cases were accepted for study. In all, 70 cases of SBA together with 2070 controls matched by age, sex, and region were interviewed. A high intake (more than 24 g alcohol per day) of beer or spirits was associated with SBA, an odds ratio (OR) of 3.5 and 95% confidence intervals (CI) of 1.5-8.0 and 3.4 (95% CI 1.3-9.2), respectively). There was no association with wine intake or total alcohol intake. Tobacco smoking was probably unrelated to SBA. CONCLUSIONS: A high intake of beer or spirits seems to be a risk factor for SBA. Since this association was not seen for wine drinkers, protective components of wine may counterbalance a carcinogenic effect of alcohol on the small bowel. Alternatively, the result may be confounded by other factors, e.g. dietary factors.

Adenocarcinoma↗
PubMed2000

Spontaneous abortion and physical strain around implantation: a follow-up study of first-pregnancy planners.

Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short time periods are the relevant measure. We followed a cohort of first pregnancy planners from termination of birth control until pregnancy for a maximum of six menstrual cycles. The analyses include 181 pregnancies, of which 32 were subclinical pregnancies detected by hCG analysis only. During early pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date of ovulation was 2.5 (95% CI = 1.3-4.6).

Abortion, Spontaneous↗
PubMed2000

Occupation and small bowel adenocarcinoma: a European case-control study.

OBJECTIVES: Because of the rarity of small bowel adenocarcinoma (SBA), little is known about the aetiology of this disease. This study aimed to identify occupational clustering of cases SBA as a systematic approach to new hypotheses on the aetiology of this disease. METHODS: A European multicentre case-control study was conducted in 1995-7, inclusive. Incident cases aged 35-69 years with SBA (n=168) were recruited before acceptance by a pathologist. Altogether 107 cases and 3915 controls were accepted, of which 79 cases, 579 colon cancer controls, and 2070 population controls were interviewed. RESULTS: The strongest industrial risk factors for SBA taking account of 10 years' exposure lag were dry cleaning, manufacture of workwear, mixed farming (women), and manufacture of motor vehicles (men). A significantly increased risk of SBA (odds ratio (OR) and 95% confidence interval (95% CI)) was found among men employed as building caretakers, OR 6.7 (1.7 to 26.0) and women employed as housekeepers, OR 2.2 (1.1 to 4.9); general farm labourers, OR 4.7 (1.8 to 12.2); dockers, OR 2.9 (1.0 to 8.2); dry cleaners or launderers, OR 4.1 (1.2 to 13.6); and textile workers (sewers or embroiderers), OR 2.6 (1.0 to 6.8). For the last four groups, together with welders OR 2.7 (1.1 to 6.6) (men) an exposure-response pattern was found when calculating the ORs for jobs held 1-5 years and >5 years, with never having held the job as reference. The ORs (95% CIs) for 1-5 years and >5 years were 4.3 (0.4 to 44.0) and 3.5 (0.9 to 13.7), 3.0 (0.3 to 26.2) and 4.3 (0.9 to 21.2), 4.6 (0.4 to 48.1) and 11.0 (2.0 to 60.4), 1.3 (0.2 to 11.0) and 5.8 (2.0 to 17.2), and 2.8 (0.3 to 23.8) and 4.6 (1.3 to 16.6), respectively, for each of these occupations. Among welders, people performing semiautomatic arc welding (MIG/MAG) were identified as a high risk group (OR 5.0 (1.3 to 19.6)). CONCLUSIONS: This explorative study suggests an increased occurrence of SBA in certain occupations, which needs further evaluation.

Adenocarcinoma↗
PubMed2000

Male-mediated spontaneous abortion among spouses of stainless steel welders.

OBJECTIVES: Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among spouses of stainless-steel welders. METHODS: A cohort of first-pregnancy planners was recruited from members of the union of metal workers and 3 other trade unions. The cohort was followed for 6 menstrual cycles from the cessation of contraceptive use. Altogether, 280 pregnancies were conceived, of which 35 were detected by human chorionic gonadotrophic hormone analysis and did not survive to a clinically recognized pregnancy. Information on exposure was collected prospectively in relation to the outcome and was available for all cycles resulting in a pregnancy. Information on pregnancy outcome was collected for all 245 clinically recognized pregnancies. RESULTS: Increased risk of spontaneous abortion was found for pregnancies with exposure to paternal stainless-steel welding (adjusted relative risk 3.5, 95% confidence interval 1.3-9.1). The results were consistent in analyses of both biochemically and clinically recognized abortions. There was no increased risk for spontaneous abortion in pregnancies with paternal exposure to the welding of metals other than stainless steel. CONCLUSIONS: Male welding of stainless steel was associated with an increased risk of spontaneous abortion in spouses. A mutagenic effect of hexavalent chromium has been found previously in both somatic and germ cells, and the findings could be due to mutations in the male genome.

Abortion, Spontaneous↗
PubMed2000

Time to pregnancy among male workers of the reinforced plastics industry in Denmark, Italy and The Netherlands. ASCLEPIOS.

OBJECTIVES: The relationship between occupational styrene exposure and male fecundity was examined. METHODS: Among 1560 Danish, Italian, and Dutch reinforced plastics workers, 220 styrene-exposed workers and 382 unexposed referents who had fathered a child were identified. A total of 768 historical styrene measurements conducted in 1970-1996 in the study companies formed the basis for semiquantitative exposure assessment in combination with measurements of urinary styrene metabolite levels. All the subjects were interviewed about work conditions and other factors potentially related to reduced fecundity. Fecundity was measured as the reported time to pregnancy (number of months a couple needed to conceive their youngest child). RESULTS: A statistically nonsignificantly reduced fecundity was observed for the styrene-exposed workers [fecundity ratio 0.79, 95% confidence interval (95% CI) 0.59-1.05]. But no consistent pattern of a detrimental effect on fecundity was found when time to pregnancy was related to worktasks indicating higher styrene exposure levels or semiquantitative or quantitative measures of styrene exposure. The workers with high exposure showed a fecundity ratio of 1.09 (95% CI 0.69-1.72). CONCLUSIONS: It is unlikely that styrene exposure has a strong effect on male fecundity.

Adult↗
PubMed1999

[Semen quality and fertility in a population-based follow-up study].

Little is known about the importance of semen quality in male infertility. We followed 430 first pregnancy planners with no previous reproductive experience recruited among more than 50,000 cohabiting trade-union members. The couples were consecutively enrolled into the study as they discontinued contraception and were followed up for six month menstrual cycles or until a pregnancy was verified. Each man provided a semen sample at enrollment. Women kept daily record of vaginal bleeding and sexual activity. The probability of conception increased with increasing sperm concentration up to 40 x 10(6)/ml, but any higher sperm density was not associated with additional likelihood of pregnancy. The proportion of sperm with normal morphology was strongly related to likelihood of pregnancy, independently of sperm concentration. In conclusion, sperm concentration and morphology are valuable biological markers of male fecundity. Reference values for semen quality based on biological knowledge can be established.

Biomarkers↗
PubMed1999

Why do short term workers have high mortality?

Increased mortality is often reported among workers in short term employment. This may indicate either a health-related selection process or the presence of different lifestyle or social conditions among short term workers. The authors studied these two aspects of short term employment among 16,404 Danish workers in the reinforced plastics industry who were hired between 1978 and 1985 and were followed to the end of 1988. Preemployment hospitalization histories for 1977-1984 were ascertained and were related to length of employment between 1978 and 1988. Workers who had been hospitalized prior to employment showed a 20% higher risk of early termination of employment than those never hospitalized (rate ratio (RR) = 1.20, 95% confidence interval (CI) 1.16-1.29), and the risk increased with number of hospitalizations. For workers with two or more preemployment hospitalizations related to alcohol abuse or violence, the rate ratios for short term employment were 2.30 (95% CI 1.74-3.06) and 1.86 (95% CI 1.35-2.56), respectively. An unhealthy lifestyle may also be a determinant of short term employment. While it is possible in principle to adjust for lifestyle factors if proper data are collected, the health-related selection of workers requires careful consideration when choosing a reference group for comparative studies of cumulative occupational exposure.

Adult↗
PubMed1999

Menstrual cycle pattern and fertility: a prospective follow-up study of pregnancy and early embryonal loss in 295 couples who were planning their first pregnancy.

OBJECTIVE: To characterize how the menstrual cycle pattern relates to fertility regardless of potential biases caused by inappropriate coital timing during the menstrual cycle or early embryonal loss. DESIGN: Prospective follow-up study. SETTING: Healthy couples recruited throughout Denmark. PATIENT(S): Two hundred ninety-five couples who were planning their first pregnancy were followed up from the discontinuation of birth control until a pregnancy was recognized within six menstrual cycles. Early embryonal losses were detected by changes in urinary hCG levels. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The probability of pregnancy occurring within one menstrual cycle (fecundity). RESULT(S): In women who had a cycle length that differed by >10 days from the usual cycle length, fecundity was approximately 25% that of women who had no variation (odds ratio 0.25, 95% confidence interval 0.09-0.68). When the combined effect of cycle variation and cycle length was assessed, cycle variation was a persistent strong predictor of fecundity. CONCLUSION(S): The mechanisms of the present findings probably are female functional disturbances in ovulation, conception, implantation, or sustained pregnancy, linked with variable menstrual cycle length. Thus, identification of medical and environmental causes of abnormal menstrual cycle patterns may provide clues to the causes of infertility. Moreover, the menstrual cycle pattern also should be taken into consideration in the clinical decision-making process.

Abortion, Spontaneous↗
PubMed1999

Distress and reduced fertility: a follow-up study of first-pregnancy planners.

OBJECTIVE: To assess the effect of psychological distress on time to first pregnancy. DESIGN: A follow-up study of time to pregnancy with prospective data on distress, with controlling for potential confounding variables. SETTING: Two university hospitals. PATIENT(S): Danish couples (n = 430) who were planning their first pregnancy and had no previous reproductive experience were followed for six menstrual cycles. Psychological distress was measured in each menstrual cycle by the General Health Questionnaire. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): A clinically recognized pregnancy or a biochemical pregnancy detected in urine samples from each period of vaginal bleeding. RESULT(S): For cycles with the highest distress score (General Health Questionnaire score >80th percentile), the probability of conception per cycle was 12.8%, compared with 16.5% in other cycles (adjusted odds ratio [OR] 0.6; 95% confidence interval [CI] 0.4-1.0). The effect of distress was found almost exclusively among women with long menstrual cycles (OR 0.1; 95% CI 0.01-0.4 and OR 0.9; 95% CI 0.5-1.4 for women with cycles of > or =35 and <35 days, respectively). An increased incidence of early embryonal loss was also found among highly distressed women with long cycles, but was based on a small number of observations. CONCLUSION(S): Psychological distress may be a risk factor for reduced fertility in women with long menstrual cycles.

Abortion, Spontaneous↗
PubMed1999

Extremely low frequency magnetic fields and fertility: a follow up study of couples planning first pregnancies. The Danish First Pregnancy Planner Study Team.

OBJECTIVES: To evaluate the impact of extremely low frequency (ELF) magnetic fields on markers of human fertility. METHODS: A follow up study of time to pregnancy, semen quality, and reproductive hormones was conducted among couples planning first pregnancies (36 males were welders and 21 were non-welders). The male and the female partner were monitored for exposure to ELF magnetic field by personal exposure meters. As summary measures of exposure the median value was calculated together with the 75 percentile value and the proportion of measurements exceeding 0.2 and 1.0 microT, respectively. Each summary measure was divided in three categories: low, medium, and high. RESULTS: Couples in which the man had a medium or a high proportion of measurements > 1.0 microT had a reduced probability of conception per menstrual cycle compared with the men with low exposure, but the result was only significant for the men with medium exposure. This finding was partly attributable to a high probability of conception per menstrual cycle among the men with low exposure compared with non-welders in the original cohort of 430 couples. Other summary measures were not related to probability of conception or other markers of fertility. A possible negative association was found between high probability of conception and female exposure measures based on the median, the 75 percentile, and the proportion of measurements > 0.2 microT, but no association was found with the proportion of measurements > 1.0 microT. CONCLUSIONS: The findings provide no consistent support for a hypothesis of a deleterious effect of low level ELF magnetic fields on markers of human fertility. However, due to the relatively small size of the studied population only large associations would be detected.

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

Objectives, designs and populations of the European Asclepios study on occupational hazards to male reproductive capability.

The main objective of the Asclepios program was to examine occupational risk factors for the male reproductive system. The program focused on occupational exposure to fungicides (farmers, greenhouse workers, and vineyard workers), styrene (laminators in the reinforced plastics industry) and inorganic lead (battery workers, foundry workers, and lead smelters). Questionnaire studies of time to pregnancy were combined with longitudinal and cross-sectional studies of semen quality. The 8 data-collecting centers addressed 6553 male workers and contributed time-to-pregnancy values on the 3077 most recent pregnancies. Data collection was by interview or self-collection. The average response rate across all exposures and centers was 69.8%. The Asclepios project is the first international multicenter research project on environmental risks to male reproductive function. A protocol for epidemiologic research on occupational risk factors to the male reproductive system was developed, and links between epidemiologic and experimental units were established. The majority, but not all, of the studies was completed within the given time frame.

Adult↗