Occupational risk of COVID-19 in foreign-born employees in Denmark

BACKGROUND

Foreign-born workers in high-income countries experience higher rates of COVID-19 but the causes are only partially known.

AIMS

To examine if the occupational risk of COVID-19 in foreign-born workers deviates from the risk in native-born employees in Denmark.

METHODS

Within a registry-based cohort of all residents employed in Denmark (n = 2 451 542), we identified four-digit DISCO-08 occupations associated with an increased incidence of COVID-19-related hospital admission during 2020-21 (at-risk occupations). The sex-specific prevalence of at-risk employment in foreign born was compared with the prevalence in native born. Moreover, we examined if the country of birth modified the risk of a positive SARS-CoV-2 polymerase chain reaction (PCR) test and COVID-19-related hospital admission in at-risk occupations.

RESULTS

Workers born in low-income countries and male workers from Eastern Europe more often worked in at-risk occupations (relative risks between 1.16 [95% confidence interval {CI} 1.14-1.17] and 1.87 [95% CI 1.82-1.90]). Being foreign-born modified the adjusted risk of PCR test positivity (test for interaction P < 0.0001), primarily because of higher risk in at-risk occupations among men born in Eastern European countries (incidence rate ratio [IRR] 2.39 [95% CI 2.09-2.72] versus IRR 1.19 [95% CI 1.14-1.23] in native-born men). For COVID-19-related hospital admission, no overall interaction was seen, and in women, country of birth did not consistently modify the occupational risk.

CONCLUSIONS

Workplace viral transmission may contribute to an excess risk of COVID-19 in male workers born in Eastern Europe, but most foreign-born employees in at-risk occupations seem not to be at higher occupational risk than native born.

Occupational exposure to whole body vibrations and birth outcomes - A nationwide cohort study of Swedish women

BACKGROUND

More women in reproductive ages are entering occupations where exposure to whole body vibrations (WBV) is common (e.g. in transportation and construction). Previous studies based on self-assessed exposure suggest increased risks of adverse birth outcomes, but it is unclear at what exposure levels and if the current exposure guidelines are appropriate during pregnancy.

OBJECTIVES

To investigate whether occupational WBV-exposure increases the risk of preterm birth, low birth weight, and/or small-for-gestational age, in a large, nationwide, prospective, cohort study.

DESIGN

The Fetal Air Pollution Exposure cohort (FAIR) was formed by merging data from multiple, national registers, and the present study includes singletons born 1994-2014 to working women in Sweden (n = 1,091,080 births). WBV-exposure was assessed quantitatively using a job-exposure matrix based on measurements, and calculated odds ratios were adjusted for potential confounders such as smoking and BMI, and other occupational exposures like noise, combustion particles, and physically and psychologically strenuous work. Data on absence from work (full-/part time, sick leave, parental leave, etc.) was also used.

RESULTS

Exposure to WBV during pregnancy, among women with low absence from work (n = 476,419), was associated with an increased risk of preterm birth, below the occupational exposure limit (1.15 m/s²). Compared to unexposed mothers, the OR was 1.38 (95% CI: 1.05, 1.83) for exposure ≥0.5 m/s², corresponding to an increase from 47/1000 cases to 65/1000 cases. No increased risk was found for small-for-gestational age.

CONCLUSIONS

Exposure to WBV was associated with an increased risk of preterm birth. The results suggest that the current permissible exposure and action levels for WBV-exposure do not adequately protect pregnant women with continuous exposure.

Association between semen parameters and chance of fatherhood - a long-term follow-up study

BACKGROUND

Evaluation of male fertility includes standard semen analysis; however, there is uncertainty about the value of sperm parameters in predicting fertility.

OBJECTIVE

To evaluate the association between semen parameters and fatherhood during a long-time period.

MATERIALS AND METHODS

Semen parameters (total sperm count, concentration, motility, and morphology) and sperm DNA fragmentation Index (DFI) assessed on samples collected from 195 Norwegian men from the general population in 2001/2002 were matched with information about fatherhood until 2015, obtained from the Medical Birth Register. The parameters were dichotomized as normal vs. abnormal according to the WHO reference values from 1999 and 2010. Cut-offs at 20% and 30% were used for DFI.

RESULTS

Among men who had no children before 2003, those with normal progressive sperm motility had more often become fathers (WHO 1999, cut-off ≥50%, adjusted OR 2.8, 95% CI 1.3-6.1 and WHO 2010, cut-off ≥32%; aOR 4.2, 95% CI 1.1-15). Based on the WHO 1999 reference value, men with normal sperm concentration (≥20 × 10⁶ /mL) had more often become fathers (aOR 3.1, 95% CI 1.1-8.6). Men with progressive sperm motility ≥50% and concentration ≥20 × 10⁶ /mL did more often achieve fatherhood (aOR 8.4, 95% CI 2.1-34). For DFI, there was a borderline significance at cut-off 20% in the group of men who had ever been fathers (OR 2.7, 95% CI 1.0-7.0 p < 0.05).

DISCUSSION

The results indicate that sperm progressive motility, sperm concentration, and DFI are associated with fatherhood during a longer time period, with sperm motility being most consistent. Although the sample size is relatively small and our results should be replicated in larger studies, they may be of clinical relevance.

CONCLUSION

Semen parameters may have a diagnostic value not only in a short time frame but also for predicting future fertility potential.

Microstructural white matter alterations and hippocampal volumes are associated with cognitive deficits in craniopharyngioma

CONTEXT

Patients with craniopharyngioma (CP) and hypothalamic lesions (HL) have cognitive deficits. Which neural pathways are affected is unknown.

OBJECTIVE

To determine whether there is a relationship between microstructural white matter (WM) alterations detected with diffusion tensor imaging (DTI) and cognition in adults with childhood-onset CP.

DESIGN

A cross-sectional study with a median follow-up time of 22 (6-49) years after operation.

SETTING

The South Medical Region of Sweden (2.5 million inhabitants).

PARTICIPANTS

Included were 41 patients (24 women, ≥17 years) surgically treated for childhood-onset CP between 1958-2010 and 32 controls with similar age and gender distributions. HL was found in 23 patients.

MAIN OUTCOME MEASURES

Subjects performed cognitive tests and magnetic resonance imaging, and images were analyzed using DTI of uncinate fasciculus, fornix, cingulum, hippocampus and hypothalamus as well as hippocampal volumetry.

RESULTS

Right uncinate fasciculus was significantly altered (P ≤ 0.01). Microstructural WM alterations in left ventral cingulum were significantly associated with worse performance in visual episodic memory, explaining approximately 50% of the variation. Alterations in dorsal cingulum were associated with worse performance in immediate, delayed recall and recognition, explaining 26-38% of the variation, and with visuospatial ability and executive function, explaining 19-29%. Patients who had smaller hippocampal volume had worse general knowledge (P = 0.028), and microstructural WM alterations in hippocampus were associated with a decline in general knowledge and episodic visual memory.

CONCLUSIONS

A structure to function relationship is suggested between microstructural WM alterations in cingulum and in hippocampus with cognitive deficits in CP.

Maternal smoking during pregnancy and daughters' risk of gestational diabetes and obesity

AIMS/HYPOTHESIS

The primary aim of the study was to investigate the risk of developing gestational diabetes in women who were exposed to tobacco smoke in utero. Secondary aims were to assess the risk of obesity and non-gestational diabetes.

METHODS

Data were retrieved from the Medical Birth Register of Sweden for women who were born in 1982 (when smoking data were first registered) or later and who had given birth to at least one child; 80,189 pregnancies were included. The associations between in utero smoking exposure (three categories: non-smokers, 1-9 cigarettes/day [moderately exposed] and >9 cigarettes/day [heavily exposed]) and subsequent gestational diabetes (n = 291), non-gestational diabetes (n = 280) and obesity (n = 7,300) were assessed.

RESULTS

The adjusted ORs (aORs) of gestational diabetes were increased among women who were moderately (1.62, 95% CI 1.24, 2.13) and heavily (1.52, 95% CI 1.12, 2.06) exposed. The corresponding aORs of obesity were 1.36 (95% CI 1.28, 1.44) and 1.58 (95% CI 1.48, 1.68), respectively. A reduced OR for non-gestational diabetes was seen in the offspring of heavy smokers (aOR 0.66, 95% CI 0.45, 0.96).

CONCLUSIONS/INTERPRETATION

Women exposed to smoking during fetal life were at higher risk of developing gestational diabetes and obesity.

Non-linear association between androgen receptor CAG and GGN repeat lengths and reproductive parameters in fertile European and Inuit men

Recently the dogma that there is an inverse linear association between androgen receptor (AR) CAG and GGN polymorphisms and receptor activity has been challenged. We analysed the pattern of association between 21 male reproductive phenotypes and AR CAG/GGN repeat lengths in 557 proven-fertile men. A linear association was only found between sperm DNA fragmentation index (DFI) and CAG length, and between inhibin B and GGN length. Men with longer CAG then the reference (22-24), had higher oestradiol levels, whereas men with shorter CAG stretches had a higher DFI and a higher proportion of Fas-positive germ cells. Subjects with either short or long CAG had increased seminal levels of prostate-specific antigen and neutral α-glucosidase activity. Compared to men with the median GGN length of 23, those with shorter GGN repeats had higher levels of inhibin B, higher proportions of normal and progressive sperm, and a higher fraction of Fas-positive sperm, while men with longer GGN had higher oestradiol levels. These data indicate that at least for some markers of male reproductive function the association with CAG or GGN repeat length is curvilinear.

No secular trend over the last decade in sperm counts among Swedish men from the general population

INTRODUCTION

Based on historical data, a decline in sperm counts during the years 1940-1990 has been suggested and aetiologically linked to a concomitant increase in the incidence of testicular cancer. This study, focusing on possible changes in sperm parameters among young Swedish men, during the past 10 years, was specifically designed in order to answer the question of whether there is a continuing decline in sperm counts.

METHODS

During the period 2008-2010, 295 young (17-20 years; median 18) men born and raised in Sweden were recruited at the age they were supposed to undergo medical examination prior to military service. The participants filled in questionnaires, underwent andrological examination and delivered an ejaculate. Their semen parameters were compared with those of a similar cohort of men (n = 216) recruited in the year 2000-2001.

RESULTS

No significant changes (means; 2000-2001 versus 2008-2010) in sperm concentration (78 × 10⁶/ml versus 82 × 10⁶/ml; P = 0.54), semen volume (3.1 ml versus 3.0 ml; P = 0.26) or total sperm counts (220 × 10⁶ versus 250 × 10⁶; P = 0.18) were found. The proportion of progressively motile spermatozoa also remained unchanged.

CONCLUSIONS

Between the years 2000 and 2010 we found no evidence of time-related deterioration of semen parameters among young Swedish men from the general population. This finding does not exclude that such a decrease may have taken place before year 2000. If the risk of testicular cancer is linked to the sperm counts, the increase in incidence of this malignancy should be levelling off in southern Sweden in the next 10-15 years.

Modifying effect of the AR gene trinucleotide repeats and SNPs in the AHR and AHRR genes on the association between persistent organohalogen pollutant exposure and human sperm Y : X ratio

Persistent organohalogen pollutants (POPs) have been suggested to be involved in changing the proportion of ejaculated Y-bearing sperm. The androgen receptor (AR), aryl hydrocarbon receptor (AHR) and aryl hydrocarbon receptor repressor (AHRR) may modulate the effect of POPs with regard to previously observed sperm Y:X ratio changes. The objective of this study was to investigate whether sperm Y:X ratio changes in subjects exposed to 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p'-DDE) were modified by polymorphisms in the AR, AHR and AHRR genes. Semen for analysis of Y- and X-bearing sperm by two-colour fluorescence in situ hybridization and blood for leukocyte DNA genotyping and analysis of CB-153 and p,p'-DDE concentrations were obtained from 195 Swedish fishermen. The polymorphic CAG and GGN repeats in the AR and the R554K and P185A single-nucleotide polymorphisms in the AHR and AHRR genes, respectively, were determined by direct sequencing and allele-specific PCR. The effect of p,p'-DDE was modified by CAG or GGN repeat category in relation to the proportion of Y-bearing sperm (P = 0.005 and 0.02 for CAG and GGN, respectively). Moreover, p,p'-DDE, but not CB-153, levels were associated with Y-sperm proportion in men with CAG < 22 (P < 0.001), but not in those carrying CAG > or = 22 (P = 0.73). This association was even more pronounced in subjects carrying a short CAG repeat in combination with an AHRR G-allele. The association in regard to p,p'-DDE was found for GGN = 23 but not for the GGN < 23 or GGN > 23 subgroups (P = 0.01, 0.44 and 0.99, respectively). In conclusion The endocrine-disrupting action of POPs, in relation to the observed changes in sperm Y:X ratio, may be modulated by the genes involved in sex steroid and dioxin-mediated pathways.

Relationships between sperm DNA fragmentation, sperm apoptotic markers and serum levels of CB-153 and p,p′-DDE in European and Inuit populations

Persistent organochlorine pollutants (POPs) are suspected to interfere with hormone activity and the normal homeostasis of spermatogenesis. We investigated the relationships between sperm DNA fragmentation, apoptotic markers identified on ejaculated spermatozoa and POP levels in the blood of 652 adult males (200 Inuits from Greenland, 166 Swedish, 134 Polish and 152 Ukrainian). Serum levels of 2, 2′, 4, 4′, 5, 5′-hexachlorobiphenyl (CB-153), as a proxy of the total POP burden, and of 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene (p,p′-DDE), as a proxy of the total DDT exposure were determined. Sperm DNA fragmentation was measured by using the TUNEL assay, whereas immunofluorescence methods were utilized for detecting pro-apoptotic (Fas) and anti-apoptotic (Bcl-xL) markers. Both TUNEL assay and apoptotic markers were statistically differed across the four populations. No correlation between neither sperm DNA fragmentation nor apoptotic sperm parameters and the large variations in POPs exposure was observed for the separate study groups. However, considering the European populations taken together, we showed that both %TUNEL positivity and Bcl-xL were related to CB-153 serum levels, whereas our study failed to demonstrate any relations between DDE and %TUNEL positivity and apoptotic sperm biomarkers (Fas and Bcl-xL) in any region or overall regions. These results suggest that CB-153 and related chemicals might alter sperm DNA integrity and Bcl-xL levels in European adult males, but not in the highly exposed Inuit men. Additional issues (genetic background, lifestyle habits and characterization of total xeno-hormonal activities) need to be investigated in order to fully assess the population variations observed.

Androgen receptor gene GGN repeat length and reproductive characteristics in young Swedish men

BACKGROUND

The human androgen receptor (AR) gene contains two polymorphisms of CAG and GGN repeats respectively. The GGN repeat function is still largely unknown and to date there are no in vivo data on this segment with respect to the general population.

METHODS

We investigated the impact of CAG and GGN repeats on male reproductive function, one by one and in interaction with each other, in 220 adolescent men from the general Swedish population. Physical examination and semen analysis, including accessory sex gland markers and measurement of reproductive hormone levels, were performed. Lifestyle-associated factors, including maternal smoking during pregnancy, were recorded. GGN and CAG repeat lengths were determined by sequencing.

RESULTS

GGN<23 was associated with lower semen volume when compared to GGN=23 (mean difference -0.6 ml, P=0.02) and GGN>23 (mean difference -0.9 ml, P=0.002). Men with GGN<23, exposed to maternal smoking during pregnancy, had higher body mass index compared to men with other GGN lengths, no matter whether their mother had smoked or not during pregnancy (mean difference 4.8 kg/m2, P<0.001).

CONCLUSIONS

Short GGN repeats seem to be associated with decreased semen volume, possibly due to suboptimal AR activity. Body composition may be influenced by the combination of fetal exposure to maternal smoking and certain AR genotypes.

Ocular and airway symptoms related to organic acid anhydride exposure--a prospective study

BACKGROUND

Organic acid anhydrides (OAA) are used as hardeners in epoxy resin systems. They are powerful sensitizers giving frequent rhinitis and asthma in exposed workers. Incidence of symptoms is unknown. Here we present the first prospective study on the associations between OAA exposure, symptoms, and effects of confounding factors.

METHODS

All new employees in three plants handling OAA were followed for up to 8.5 years. Before the employment, a questionnaire reporting about symptoms of eyes and airways, smoking habits, and atopy was answered. The subjects were asked at regular medical examinations about work tasks and work-related symptoms. Serum was analysed for specific OAA antibodies.

RESULTS

Mean exposures varied between 6 and 39 microg/m3. The incidence for work-related symptoms of the eyes, nose, pharynx, and lower airways was 91, 64, 46, and 31 per 1000 years of exposure, respectively. Symptoms were found frequently, even at mean exposure level at <10 microg/m3. Smoking and atopy increased the risk of symptoms. Immunoglobulin (Ig)E sensitized workers had a significant increased risk for symptoms of the eyes and pharynx and for running nose/sneezing.

CONCLUSIONS

Organic acid anhydrides exposure is associated with frequent ocular and airway symptoms even at mean exposure levels at <10 microg/m3. There is an important need for establishment of an occupational threshold limit. A limit value of below 5 microg/m3 is proposed.

Factors affecting time to pregnancy

BACKGROUND

Both lifestyle factors and occupational and environmental factors have been suggested to affect the female reproductive system. In the present study, the separate and joint effects of several such factors are investigated.

METHODS

Information on time to pregnancy (TTP) was available for 1578 women randomly selected from the general Swedish population. The information was collected retrospectively by using self-administered questionnaires. By means of logistic regression of survival data, fecundability odds ratios were determined for many factors. Multivariate models were used to determine which factors had the most impact on TTP.

RESULTS

Several lifestyle factors were found to associate with TTP. However, only use of oral contraceptives prior to attempting to conceive, menstrual cycle length, age at conception and parity remained in the multivariate models. Together, these factors explained 14% of the variance in TTP. Excluding first and second month conceptions, only age at conception and menstrual cycle length remained in the multivariate models, together explaining only 8% of the variance in TTP.

CONCLUSIONS

Although information on several factors was available, the multivariate model explained only a small fraction of the variation in the observed time to pregnancies. Furthermore, female biological factors seemed more important predictors of TTP than lifestyle factors.

Exposure to persistent organochlorine pollutants and seminal levels of markers of epididymal and accessory sex gland functions in Swedish men

BACKGROUND

A major exposure route for persistent organochlorine pollutants (POPs) in Sweden is through consumption of fatty fish from the Baltic Sea. Endocrine disruptors, such as POPs, may have a negative impact on sperm quality. The present study aimed to investigate whether exposure to 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE) affects epididymal and accessory sex gland function.

METHODS

157 fishermen from the coastal stretches of Sweden, aged 27-67 years, provided semen samples which were analyzed for prostate-specific antigen (PSA), neutral alpha-glucosidase (NAG), fructose and zinc levels. Serum levels of CB-153 and p'p-DDE were determined.

RESULTS

The median CB-153 serum level was 189 ng/g lipid (range 40-1460) and a median p,p'-DDE serum level 231 ng/g lipid (range 40-2252). There was a significant linear association between CB-153 and total amount of PSA (slope [beta] = -2.5, 95% confidence interval [CI] -4.0, -0.9; P = 0.02). With age, abstinence time and smoking included in the model the association became non-significant (beta = -1.4, 95% CI-3.0, 0.1; P = 0.07). There were no significant associations between CB-153 and zinc, fructose and NAG. As for the exposure variable p,p'-DDE and the outcome variables, no significant associations were found.

CONCLUSIONS

The study gives only very limited support of an association between CB-153 in serum and total PSA, and a random finding cannot be excluded.

Exposure to CB-153 and p,p'-DDE and male reproductive function

BACKGROUND

During the last decades, there has been concern that exposure to endocrine disruptors, such as persistent organochlorine pollutants (POPs), may contribute to an impairment of male reproductive function. To investigate whether exposure to 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE) affects semen quantity and quality and reproductive hormones, 195 Swedish fishermen, aged 24-65 years, were investigated.

METHODS

The men provided semen samples which were analysed in a mobile laboratory unit. Blood samples and information relating to lifestyle, medical and reproductive history were obtained.

RESULTS

The subjects had a median CB-153 serum level of 193 ng/g lipid (range 39-1460) and a median p,p'-DDE serum level of 240 ng/g lipid (range 334-2251). When CB-153 was categorized into quintiles, the subjects in the quintile with the highest concentration (> 328 ng/g lipid), tended to have decreased sperm motility compared with the subjects in the lowest quintile (< 113 ng/g lipid). The age-adjusted mean difference was 9.9% (95% confidence interval -1.0 to 21% P = 0.08). We found no significant associations between p,p'-DDE and semen characteristics or reproductive hormones.

CONCLUSION

The association between CB-153 and sperm motility, although not formally significant, is of interest considering the possible endocrine-disrupting effects of polychlorinated biphenyls (PCBs).

Pooled analysis of clinical and cytogenetic features in treatment-related and de novo adult acute myeloid leukemia and myelodysplastic syndromes based on a consecutive series of 761 patients analyzed 1976-1993 and on 5098 unselected cases reported in the literature 1974-2001

To ascertain the frequency of treatment-related acute myeloid leukemias and myelodysplastic syndromes (t-AML/t-MDS) in an unselected series, we have identified all adult cases analyzed in our department from 1976 to 1993. Further aims were to compare karyotypic features of t-AML/t-MDS with de novo AML/MDS, in our material as well as in 5098 unselected, cyto- genetically abnormal, published cases, and to analyze associations between type of prior therapy and karyotype. Among our 372 AML and 389 MDS, 47 (13%) were t-AML and 62 (16%) were t-MDS. Clonal abnormalities were significantly more common in t-AML and t-MDS than in de novo disease (68% vs 50%, P < 0.05 and 84% vs 45%, P < 0.001, respectively). Among the available 4230 AML and 1629 MDS (the present series and published cases), 14% were t-AML and 15% were t-MDS. In t-AML/t-MDS, the number of anomalies and the ploidy levels differed significantly from de novo cases, with complex and hypodiploid karyotypes being more common in t-AML/t-MDS. In t-AML, unbalanced changes in general, t(1;3), der(1;7), 3p-, -5, 5q-, -7, 7q-, t(9;11), t(11;19), t(11q23), der(12p), -17, der(17p), -18, and -21 were significantly more frequent than in de novo AML. In t-MDS, -5, -7, 7q-, 13q-, der(17p), and -18 were significantly more common. Type of prior treatment correlated significantly with number of anomalies in t-AML and with ploidy levels in t-AML/t-MDS. The frequencies of several aberrations varied with type of therapy, eg, 5q- was more frequent in radiotherapy-associated t-MDS, monosomy 7 was more common in t-AML and t-MDS after treatment with alkylators, and t(11q23) in t-AML was associated with topoisomerase II inhibitors. Abnormalities significantly more common in de novo disease were +8 as a sole anomaly, balanced changes in general, t(8;21), t(9;22), t(15;17), inv(16), and t(21q22) in AML, and -Y, 5q-, and 20q- as sole anomalies and +8 in MDS. The results emphasize the strong association between previous genotoxic exposure and karyotypic features.

Higher sperm counts in Southern Sweden compared with Denmark

BACKGROUND

A common aetiology behind time-related deterioration of male reproductive function, including decline of sperm concentration and rising incidence of testicular cancer and cryptorchidism, has been suggested. Accordingly, a high incidence of testicular cancer and low sperm counts have been observed in Denmark, while in Finland opposite figures were found. This may be due to genetic factors. The incidence of testicular cancer is 50% lower in Sweden than in Denmark. Data on sperm counts in a population of Danish military conscripts have been published and we wished therefore to compare them with semen parameters in a corresponding cohort from Southern Sweden, geographically and genetically very closely related to Denmark.

METHODS

A total of 305 military conscripts was recruited and investigated in an identical way as those in the Danish study including a questionnaire, physical examination and semen analysis.

RESULTS

Men born and raised in Sweden had a 23% higher mean sperm concentration, a 31% higher mean total sperm count and a 14% higher seminal volume compared with their Danish counterparts.

CONCLUSIONS

The differences in reproductive parameters between the two genetically very similar populations could not be explained by possible confounders and may be due to unknown environmental or lifestyle-related factors.

Reproductive outcome among female hairdressers

BACKGROUND

Working as a hairdresser involves exposure to a variety of chemical agents.

AIMS

To estimate the risk of such exposure in relation to reproductive outcome.

METHODS

A cohort of hairdressers, certified in Sweden from 1970 onwards, and a referent cohort of women from the general population were established and linked to the Swedish Medical Birth Register for the period 1973 to 1994. In the cohort of hairdressers 3706 women gave birth to 6960 infants. The corresponding numbers among the referents were 3462 and 6629. Questionnaires were sent to all hairdressers to obtain individual exposure data. The response rate was 65%.

RESULTS

Compared with the referents, the hairdressers more often gave birth to infants that were small for gestational age (SGA). In addition, a higher fraction of the infants born to a hairdresser had a major malformation (2.8% v 2.1%). Frequent permanent waving and spraying tended to be associated with increased risk of having an SGA infant, whereas no clear association could be seen between the individual exposure assessments and malformation risk.

CONCLUSIONS

Results indicated that hairdressers have a slight increased risk of having intrauterine growth retarded infants and infants with major malformation compared with women from the general population. However, no clear associations were seen between individual exposure assessments and these outcomes.

Cytogenetic features of multiple myeloma: impact of gender, age, disease phase, culture time, and cytokine stimulation

Relatively little is known about the cytogenetic features of multiple myeloma (MM) when compared to other hematologic malignancies. The reasons for this are most likely manifold, and include a low mitotic index of the malignant cells and the presence of cytogenetically cryptic abnormalities as well as of complex karyotypes with poor chromosome morphology. In the present study, we have investigated whether various culture conditions may influence the yield of abnormal metaphases in MM and, in the related plasma cell dyscrasias, monoclonal gammopathy of undetermined significance (MGUS) and plasmacytomas (PC). In addition, the possible impact of age, gender, and disease phase on the cytogenetic features has been analyzed. A total of 95 samples from 74 cases (68 MM, three PC, and three MGUS patients) were obtained for cytogenetic analysis. The samples were cultured either in conventional medium or in medium containing IL-6 and GM-CSF, and the culture times varied from 24 to 120 h. In total, 186 cultures were analyzed. Metaphase fluorescence in situ hybridization analysis using probes specific for 14q32, i.e. IGH rearrangements, could be performed in 57 of the 74 cases, and revealed 14q32 aberrations in 10 cases not seen by conventional G-banding. Abnormal karyotypes were detected in 77 (41%) of the 186 cultures, 46 (48%) of the 95 samples, and in 41 (55%) of the 74 patients, revealing a total of 20 chromosomal aberrations previously not reported in plasma cell dyscrasias. We found no evidence that gender, age, disease phase, culture time, or cytokine stimulation significantly influences the karyotypic features of MM.

Risk factors for developing systemic lupus erythematosus: a case-control study in southern Sweden

OBJECTIVE

To explore the risk factors that have been suggested to be associated with the development of SLE.

METHODS

A case-control study was performed and a questionnaire was developed to obtain the data. Consecutive female incident cases diagnosed between 1981 and 1999 in a defined geographical area in southern Sweden were included. Controls, matched for calendar year of birth, were selected randomly from the same area. In total, 85 cases and 205 controls agreed to participate. The questionnaire included questions about formal education, body weight and height, medical history, family history of autoimmune diseases, exposure to ultraviolet radiation, animals, hair-colouring dyes, alfalfa (lucerne) sprouts, smoking and alcohol habits, history of physical traumata, blood transfusion, silicone breast implants, exogenous oestrogens, other medication, and significant negative life events.

RESULTS

Using a multivariate model, a history of hypertension [odds ratio (OR)=3.7, 95% confidence interval (CI) 1.4-9.8], drug allergy (OR=3.6, 95% CI 1.4-9.5), a type I/II sun-reactive skin type (OR=2.3, 95% CI 1.1-4.8) and a family history of SLE (OR=6.8, 95% CI 1.4-32) were all significantly associated with an increased risk of developing SLE, whereas consumption of alcohol was inversely associated with the risk of SLE (use of alcohol very seldom, OR=1.0; 1-150 g/month, OR=0.4, 95% CI 0.2-1.0; >150 g/month, OR=0.2, 95% CI 0.1-0.5). A suggested association with increased SLE risk was seen for smoking (OR=1.8, 95% CI 0.9-3.6) and blood transfusions (OR=2.3, 95% CI 0.9-5.8). Neither exposure to exogenous oestrogen nor exposure to hair-colouring dyes was associated with SLE.

CONCLUSIONS

Risk factors of both exogenous and endogenous origin were identified in this population-based series of SLE patients.

Incidence of asthma in female Swedish hairdressers

OBJECTIVE

To investigate the risk of asthma in hairdressers.

METHODS

The incidence of asthma was retrospectively estimated in a Swedish nationwide study including all female hairdressers certified from vocational schools from 1970 to 1995, and a stratified sample of women from the general population were referents. A postal questionnaire included questions on respiratory tract symptoms, atopy, smoking, working periods as a hairdresser, and number of specific hair treatments performed/week. Reported exposures were validated by occupational hygienists. Rate ratios of incidence (IRRs) of asthma were estimated by Poisson regression, adjusted for calendar year of observation, hay fever, smoking, and region of domicile.

RESULTS

The crude incidences of asthma/1000 person-years were: 3.9 during active years as a hairdresser, 2.8 among the hairdressers when not working in the profession, and 3.1 among the referents. The corresponding IRR for being an active hairdresser compared with the referents was 1.3 (95% confidence interval (95% CI) 1.0 to 1.6). Moderate effects on risk of asthma were found both from hairdressing work (IRR=1.6 (1.1 to 2.2) among never-smokers) and from smoking (IRR=1.6 (1.2 to 2.2) among referents). However, the combined effect from hairdressing work and smoking (IRR=1.5 (1.0 to 2.1)) was less than expected (p=0.02). No effect modification by respiratory atopy was found. The hairdressers most often performing hair bleaching treatments (IRR=1.5 (0.7 to 3.0)) or using hair spray (IRR=1.4 (0.8 to 2.4)) had, compared with the most infrequent users, a slightly, but not significantly higher incidence of asthma. Exposure to persulphates in hair bleach was estimated to be 0.04-0.15 mg/m(3) during mixing of the powder. Reported average number of bleaching treatments agreed well with those performed according to a diary.

CONCLUSIONS

Active hairdressing work was associated with a moderately increased incidence of asthma among lifelong non-smokers. The results are moderately supportive, but not conclusive, of associations between asthma and exposure to hair bleach or hair spray.

Polychlorinated biphenyls in blood plasma among Swedish female fish consumers in relation to time to pregnancy

The purpose of this study was to assess the association between 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma, a biomarker of exposure to polychlorinated biphenyls (PCB), and time to pregnancy (TTP) in a group of women with a varying dietary exposure to PCB. For 121 Swedish east coast fishermen's wives (median year of birth 1956, range 1945-1968), information on selt-reported TTP for the first planned pregnancy (median 2 mo, range 0-48) and CB-153 concentrations from blood samples drawn in 1995 (median 144 ng/g lipid, range 16-566) were available. Each woman's CB-153 concentration in plasma at the time immediately preceding her pregnancy was estimated, taking into account reduction of body burden of CB-153 due to lactation, the yearly reduction of PCB in Baltic Sea fish, as well as the biological half-life of CB-153. Based on the estimated CB-153 concentrations, subjects were categorized into tertiles as low (37-206 ng/g lipid), medium (207-330 ng/g lipid), and high (331-,1036 ng/g lipid) exposure groups. TTP in the medium- and high-exposure groups were then compared to TTP in the low-exposure group by estimating the corresponding success rate (i.e., the number of pregnancies per person month) ratios (SuRR) using discrete Cox regression, taking into account essential confounders. No obvious association between estimated CB-153 concentration and TTP was observed (medium vs. low: SuRR 0.77 [95% CI 0.47-1.28] and high vs. low: SuRR 0.95 10.74-1.23]). The present data give no support for a negative association between the plasma CB-153 concentrations observed in the present study and TTP. It should, however, be borne in mind that the study group was rather small and mainly included relatively young women, likely to have been only moderately exposed.

Plasma concentrations of persistent organochlorines in relation to thyrotropin and thyroid hormone levels in women

OBJECTIVES

There is a concern that persistent organohalogen toxicants, such as polychlorinated biphenyls (PCBs), might display endocrine-disrupting effects in exposed populations. In this study the correlations between PCBs and thyrotropin (TSH) and thyroid hormone concentrations in plasma were assessed in adult women.

METHODS

The study group consisted of 182 fishermen's wives from the Swedish east coast, with a median age of 42 years (range 23-62) and a median current consumption of contaminated fatty fish from the Baltic Sea of two meals per month (range 0-12). TSH, free (FT3) and total (TT3) triiodothyronine and free (FT4) and total (TT4) thyroxin in plasma were analyzed by immunofluorometric assays, and 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma was analyzed by gas chromatography with electron capture detection. Twenty other PCB and two hydroxy-PCB congeners were analyzed in subgroups of the women. Plasma lipid analyses were performed with enzymatic techniques.

RESULTS

The CB-153 concentration in plasma (range 16-776 ng/g lipid) was negatively correlated with the TT3 concentrations (range 1.0-3.0 nmol/l, rs = -0.29, P < 0.001). This association remained after age adjustment.

CONCLUSIONS

The present study gives some support for the notion that dietary exposure to persistent organochlorine compounds (POCs) might weakly affect peripheral thyroid hormone concentrations in adult women.

Exposure to hexahydrophthalic and methylhexahydrophthalic anhydrides--dose-response for sensitization and airway effects

OBJECTIVES

This study clarified the exposure-response relationships for the organic acid anhydrides (OAA) hexahydrophthalic (HHPA) and methylhexahydrophthalic (MHHPA) anhydrides and the development of specific immunoglobulin (IG) E and G antibodies and work-related symptoms.

METHODS

In an epoxy resin-using factory, air levels of OAA were determined by gas chromatography-mass spectrometry. Occupational, smoking, and medical histories (questionnaire) were obtained for 154 exposed workers and 57 referents. Work-related symptoms of the eyes and airways were recorded, and OAA metabolites were analyzed in urine. A skin-prick test with common allergens and conjugates of OAA were performed. Specific IgE (radioallergosorbent test) and IgG (enzyme-linked immumosorbent assay) antibodies were determined in serum, and spirometry was performed.

RESULTS

Air levels of the OAA were low (HHPA < 1 to 94, MHHPA < 3 to 77 microg/m3) and associated with the concentrations of the OAA metabolites in urine. Furthermore, for the exposed workers, there were high prevalences of sensitization (IgE 22%, IgG 21%), which correlated with the exposure. Neither atopy nor smoking increased this risk significantly. Furthermore, work-related symptoms were more prevalent among the exposed workers than among the referents (eyes 23% versus 14%, nose 28% versus 16%, nose bleeding 8% versus 0%, lower airways 10% versus 4%), and they were related to the exposure (adjusted prevalence odds ratios (POR) in the highest group 7.7, 3.6 and 17, respectively) and the IgE levels (POR 4.9, 3.1 and 5.6, respectively).

CONCLUSIONS

In spite of the very low OAA levels in the air and metabolites in the urine, there were high and exposure-related risks of specific IgE and IgG sensitization and of work-related symptoms for the eyes, nose (especially bleeding), and lower airways.

Effects of lead on the endocrine system in lead smelter workers

In this study of the effects of lead on the endocrine system, 77 secondary lead-smelter workers (i.e., 62 active and 15 retired) were compared with 26 referents. Lead concentrations were determined in plasma with inductively coupled plasma mass spectrometry (i.e., index of recent exposure), in blood with atomic absorption spectrophotometry, and in fingerbone with K x-ray fluorescence technique (i.e., index of long-term exposure). In addition, pituitary hormones were determined in serum by fluoroimmunoassay, and thyroid hormones and testosterone in serum were determined with radioimmunoassay. Nine lead workers and 11 referents were challenged with gonadotrophin-releasing hormone and thyrotrophin-releasing hormone, followed by measurements of stimulated pituitary hormone levels in serum. Median levels of lead in plasma were 0.14 microg/dl (range = 0.04-3.7 microg/dl) in active lead workers, 0.08 microg/dl (range = 0.05-0.4 microg/dl) in retired lead workers, and 0.03 microg/dl (range = 0.02-0.04 microg/dl) in referents (1 microg/dl = 48.3 nmol/l). Corresponding blood lead concentrations were 33.2 microg/dl (range = 8.3-93.2 microg/dl), 18.6 microg/dl (range = 10.4-49.7 microg/dl), and 4.1 microg/dl (range 0.8-6.2 microg/dl), respectively. Respective bone lead levels were 21 microg/gm (range = -13 to 99 microg/gm), 55 microg/gm (range = 3-88 microg/gm), and 2 microg/gm (range = -21 to 14 microg/gm). Concentrations of basal serum hormone (i.e., free thyroid hormones, thyrotrophin, sex hormone binding globulin, and testosterone) were similar in the 3 groups. There were no significant associations between the hormones mentioned herein and blood plasma, blood lead, and bone lead levels. In the challenge test, stimulated follicle-stimulating hormone levels were significantly lower in lead workers (p = .014) than in referents, indicating an effect of lead at the pituitary level. Also, there was a tendency toward lower basal stimulated follicle-stimulating hormone concentrations in lead workers (p = .08). This effect, however, was not associated with blood plasma level, blood lead level, or bone lead level. In conclusion, a moderate exposure to lead was associated with only minor changes in the male endocrine function, particularly affecting the hypothalamic-pituitary axis. Given that sperm parameters were not studied, the authors could not draw conclusions about fertility consequences.

Lung cancer risks among lead smelter workers also exposed to arsenic

Recent publications indicate an increased incidence of lung cancer in non-ferrous smelter workers exposed to lead. The present study provides further data on selected subgroups in one such cohort. The cohort was based on 3979 smelter workers employed for at least 1 year between 1928 and 1979, and also exposed to lead and included in the Blood Lead Register that was started at the smelter in 1950. Two subcohorts were formed from the original cohort. One consists of 710 workers employed at the lead departments (Lead subcohort 1), and the other of 383 workers employed at the lead departments (Lead subcohort 2), but never at other works where an excess lung cancer risk was previously identified. Standardized Cancer Incidence Rates (SIR) 1958-1987 were calculated relative to county rates. In the subcohorts, arsenic exposure in lung cancer cases was assessed in detail based on occupational hygiene information from the company. Lung cancer incidence was raised in both subcohorts (Lead subcohort 1: SIR 2.4; 95% CI 1.2-4.5; Lead subcohort 2: SIR 3.6; 95% CI 1.2-8.3). Total cancer incidence in the cohorts was not increased. A detailed study of arsenic exposure in the 10 lung cancer cases in these two subcohorts revealed that all but one of these cases had a significant exposure also to arsenic. An elevated incidence of lung cancer was observed in smelter workers exposed to lead. However, considerable arsenic exposure also occurred in a majority of the lung cancer cases in the investigated subcohorts. In this multifactorial exposure situation it has not been possible to separate the carcinogenic effects of lead and arsenic, but a possible interaction between these metals may be involved in explaining the carcinogenic risks.

A prospective study of the relationship between exposure and specific antibodies in workers exposed to organic acid anhydrides

BACKGROUND

The exposure-response relationships for the induction of specific IgE and IgG were evaluated in a prospective study of workers exposed to organic acid anhydrides (OAAs). Special attention was paid to the modifying effects of atopy and smoking.

METHODS

The subjects were 163 previously unexposed persons exposed to epoxy resins with hexahydro-, methylhexahydro-, and methyltetrahydrophthalic anhydride as curing agents. The levels of OAAs in air and of specific IgE and IgG in serum were recurrently monitored. The mean observation time was 32 (1-105) months.

RESULTS

The mean combined OAA exposure of the subjects was 15.4 (< 1-189) microg/m3. Positive specific IgE was demonstrated by 21 (13%) subjects with a mean induction time of 8.8 (1-35) months. The incidence of sensitization was 4.1 cases/1000 months at risk. The relative risk (OR) for atopics was 5.4 (1.9-15.3; 95% CI). An exposure-response relationship was demonstrated by an increasing risk of sensitization with increasing exposure.

CONCLUSION

An association between exposure and atopy, respectively, and the induction of specific antibodies against OAAs were observed. The risk for atopics was comparable with the risk for the subjects in the most exposed group.

The prognostic impact of karyotypic subgroups in myelodysplastic syndromes is strongly modified by sex

The prognostic impact of karyotypic patterns in a consecutive series of 389 adult myelodysplastic syndromes (MDS) was investigated. Time period did not significantly influence the survival times. In the analyses, the MDS cases were subdivided into the cytogenetic subgroups used in the International Prognostic Scoring System, i.e. favourable [-Y, del(5q) or del(20q) as single aberrations or normal karyotype, n = 241], poor [-7, del(7q), der(1;7) or complex karyotypes, i.e. > or = three abnormalities, n = 89] and intermediate (other aberrations, n = 59). The survival times correlated well with the prognostic subgroups, confirming that the cytogenetic classification was valid. Expressed as hazard ratios (HRs), with the favourable subgroup as the reference, the intermediate and poor subgroup HRs increased to 1.5 (95% confidence interval, 1.1-2.1) and 3.2 (2.4-4.1) respectively. Sex, age, morphological subtype and smoking habits significantly modified this prognostic impact. Shorter survival was detected for men in the favourable and the intermediate subgroups, but not in the poor prognosis subgroup. Using women in the favourable subgroup as the reference and adjusting for age, the HR for men was 1.6 (1.2-2.1) in the favourable subgroup. Adjusting for smoking habits as well decreased the HR to 1.4 (1.1-2.0) and, when also excluding cases with del(5q) as the sole anomaly, no significant difference could be discerned [HR 1.2 (0.9-1.6], suggesting that the better outcome for women in the favourable subgroup was mainly as a result of the '5q-syndrome' and to smoking habits. In the intermediate subgroup, the corresponding HRs were 3.0 (1.5-6.0) when adjusted for age and 2.7 (1.3-5.5) when also adjusted for smoking habits. Different survival times between men and women have never previously been reported for this MDS group. Although it remains to be elucidated whether environmental and/or constitutional factors cause the observed sex-related difference, these observations have obvious clinical ramifications, not least in designing and evaluating therapy protocols.

Questionnaire versus direct technical measurements in assessing postures and movements of the head, upper back, arms and hands

OBJECTIVES

This study compares questionnaire-assessed exposure data on work postures and movements with direct technical measurements.

METHODS

Inclinometers and goniometers were used to make full workday measurements of 41 office workers and 41 cleaners, stratified for such factors as musculoskeletal complaints. The subjects answered a questionnaire on work postures of the head, back, and upper arms and repeated movements of the arms and hands (3-point scales). The questionnaire had been developed on the basis of a previously validated one. For assessing worktasks and their durations, the subjects kept a 2-week worktask diary. Job exposure was individually calculated by time-weighting the task exposure measurements according to the diary.

RESULTS

The agreement between the self-assessed and measured postures and movements was low (kappa = 0.06 for the mean within the occupational groups and kappa = 0.27 for the whole group). Cleaners had a higher measured workload than office workers giving the same questionnaire response. Moreover, the subjects with neck-shoulder complaints rated their exposure to movements as higher than those without complaints but with the same measured mechanical exposure. In addition, these subjects also showed a general tendency to rate their postural exposure as higher. The women rated their exposure higher than the men did.

CONCLUSIONS

The questionnaire-assessed exposure data had low validity. For the various response categories the measured exposure depended on occupation. Furthermore, there was a differential misclassification due to musculoskeletal complaints and gender. Thus it seems difficult to construct valid questionnaires on mechanical exposure for establishing generic exposure-response relations in epidemiologic studies, especially cross-sectional ones. Direct technical measurements may be preferable.

Muscular rest and gap frequency as EMG measures of physical exposure: the impact of work tasks and individual related factors

Owing to an orderly recruitment of motor units, low threshold type I fibres are presumed to be vulnerable in contractions of long duration. To study load on these fibres muscular rest was registered as the time fraction of electromyographic (EMG) activity below a threshold. Moreover, the frequency of periods with muscular rest, EMG gaps, was derived, since a low gap frequency has been shown to be a risk factor for musculoskeletal disorders. Trapezius EMG was registered in 24 female hospital cleaners, 21 female office workers and 13 male office workers during one working day. Cleaners have a high risk of neck/shoulder pain and had much less muscular rest than office workers measured as a percentage of total registered time (median value = 1.5%, range = 0.2-13% vs. median value = 12%, range = 0.0-32%, respectively). Gap frequency showed no difference between the two occupational groups. Both measures displayed a wide inter-individual variation. For the cleaners, some of the variance was explained by body mass index (BMI) and age, with lower values of muscular rest for older subjects with a high BMI. Among the office workers, low values of muscular rest and a high gap frequency were registered in subjects with a low subjective muscular tension tendency. Gender, strength, smoking, job strain, employment time and musculoskeletal symptoms had no impact on either EMG measure.

Exposure biomarkers and risk from gluing and heating of polyurethane: a cross sectional study of respiratory symptoms

OBJECTIVES

To define the relation between exposure to polyurethane (PUR) glue, biomarkers of exposure and effect, and work related symptoms that occur at least once a week.

METHODS

In a cross sectional study, 152 workers and 14 clerks in a factory with exposure to sprayed and heated PUR glue containing 4, 4'-diphenylmethane (MDI) or 1,6-hexamethylene (HDI) di-isocyanate were examined with gas chromatography-mass spectrometry (GC-MS) for metabolites of MDI in plasma (P-MDX) and urine (U-MDX), 2,4- and 2, 6-toluene di-isocyanate (TDI; P-TDX, U-TDX) and HDI in plasma and urine, specific serum IgG (S-IgG-MDI, S-IgG-HDI, and S-IgG-TDI, respectively) and IgE (S-IgE-MDI). Work related symptoms of the eyes and airways (nose or lower airways, or both), and lung function were also evaluated.

RESULTS

P-MDX was detected in 65% of the workers, U-TDX in 47%, HDX in none. Three per cent were positive for S-IgE-MDI, 33% for S-IgG-MDI, 32% for S-IgG-TDI, and 12% for S-IgG-HDI. A few clerks had metabolites, and some had antibodies. Most metabolites and immunoglobulins were slightly correlated-for example, P-MDX v S-IgG-MDI: r(s)=0.21. Workers who heated glue had increased P-MDX (odds ratio (OR)=12 for a value above the median) and S-IgG-MDI (OR=3.7), sprayers P-2,4-TDX (OR=6.2) and P-2,6-TDX (OR=16). Twenty six per cent of the workers had work related symptoms of the airways, 21% from the nose, 11% from the lower airways. Spraying of glue increased the risk of work related symptoms and slightly decreased lung function. U-MDX was associated with work related symptoms from the airways (OR=3.7) and P-2,6-TDX with work related symptoms from the lower airways (OR=6.6). S-IgG-MDI was related to work related symptoms from the airways (OR=2.6).

CONCLUSIONS

There were relations between exposures to sprayed and heated PUR glue based on MDI and HDI, concentrations of metabolites of MDI and TDI in plasma and urine, specific IgG serum antibodies against MDI, TDI, and HDI, and work related symptoms.

Time to pregnancy and infertility among women with a high intake of fish contaminated with persistent organochlorine compounds

OBJECTIVES

The purpose of this study was to assess the effect of persistent organochlorine compounds through the dietary intake of fatty fish from the Baltic Sea on human fertility.

METHODS

Information on time to pregnancy, subfertility, and infertility was collected retrospectively by self-administered questionnaires in 2 cohorts of fishermen's wives from the Swedish east (by the Baltic Sea) and west coasts. In addition to cohort affiliation, current fish consumption and growing up in a fishing village were used as proxies for exposure within the eastcoast cohort.

RESULTS

A decreased success (ie, pregnancy) rate and a tendency towards increased subfertility was found for heavy smokers (> or =10 cigarettes/day) in the eastcoast cohort as compared with the westcoast cohort [success rate ratio 0.66, 95% confidence interval (95% CI) 0.49-.89; subfertility odds ratio 1.64, 95% CI 0.91-2.91). However, internal analyses within the eastcoast cohort did not show that growing up in a fishing village or high current fish consumption decreased the success rate. Eastcoast cohort affiliation showed an increased risk for infertility (odds ratio 2.49, 95% CI 1.05-5.92).

CONCLUSIONS

The present data give some support for a negative association between exposure to persistent organochlorine compounds and fertility among heavy smokers. However, when the proxy exposure measures are also considered, the findings are not consistent. Better individual exposure assessments should be used before more firm conclusions are drawn.

Medical and psychometric examinations of conscripts born to mothers with a high intake of fish contaminated with persistent organochlorines

OBJECTIVES

The present study aimed to investigate whether boys who had been pre- and postnatally exposed to persistent organochlorine compounds through the consumption of contaminated fatty fish from the Baltic Sea (on the east coast of Sweden) had medical or psychometric impairments in the compulsory conscript examination at 18 years of age.

METHODS

Boys born in 1973 to 1975 to fishermen's wives and fishermen's sisters from the Swedish east coast were examined at 18 years of age. For relevant comparisons a corresponding group from the Swedish west coast, where the fish are less contaminated, were used. In addition, comparisons were made with expected values based on conscript examination data for the general population in the same geographic areas.

RESULTS

The boys in the 2 cohorts did not, during the conscript testing, significantly differ in the results of the psychometric tests. On the other hand, the boys from the eastcoast cohort were somewhat shorter and had more visual and hearing impairments than the boys from the west coast. However, the eastcoast boys did not differ from the regional reference population with respect to visual and hearing ability.

CONCLUSIONS

Although no individual exposure data were available, the present results do not support any harmful long-term impact of pre- and postnatal exposure to persistent organochlorine compounds from mothers' fish consumption on the psychometric functions of boys in their conscript examinations.

Survival time in a population-based consecutive series of adult acute myeloid leukemia--the prognostic impact of karyotype during the time period 1976-1993

A consecutive population-based series of 372 adult acute myeloid leukemias, successfully cytogenetically investigated at a single center between 1976 and 1993, is reported. All medical records were reviewed in order to ascertain the prognostic impact of karyotype, divided into three groups; favorable (t(8;21), t(15;17), and inv(16) irrespective of karyotypic complexity; n = 40), poor (der(1;7), inv(3), -5, del(5q), -7, t(9;22), and complex karyotypes including whole or partial losses of chromosomes 5 and/or 7; n = 56), and intermediate (other abnormalities or normal karyotype; n = 276). The possible modification by age, gender, time period, morphologic subtype, and bone marrow transplantation (BMT) on this prognostic impact was also determined. The chemotherapy regimens used were heterogeneous over time but principally the same at any given point in time. The majority of the patients were treated with combinations including an anthracycline and cytarabine with curative intent. Gender, morphology, and BMT did not significantly modify the effect of cytogenetic patterns on survival time, whereas age and time period did. The hazard ratios for the subgroups favorable, intermediate, and poor were 1.0, 1.2 and 1.9 at age 20-49; 1.0, 2.5 and 4.5 at age 50-64; 1.0, 4.1 and 11.4 at age 65-74; 1.0, 1.4 and 2.2 for the time period 1976-1987 and 1.0, 2.0 and 6.7 for 1988-1993. The salient feature of the Kaplan-Meier curves was the improved survival during the later time period for patients with favorable and intermediate cytogenetic abnormalities. The present findings thus suggest that it is mainly these patient groups that have benefited from advances in therapy, including supportive care.

Impact of physical exposure on neck and upper limb disorders in female workers

Physical workload [muscular load of the trapezius and infraspinatus muscles using electromyography (EMG), wrist positions and movements by electrogoniometers] and neck and upper limb disorders (from, for example, a physical examination) were studied in women with repetitive industrial work (n = 95) and referents (n = 74). The repetitive work displayed higher ratings for wrist movements, but not for EMG. The prevalences of neck, shoulder and wrist/hand disorders were elevated for women with repetitive work [age-adjusted prevalence odds ratios (PORs) 2.0-7.5]. For the left hand, high frequency of wrist movements (mean power frequency 0.53 Hz) was associated with a high prevalence of disorders (56%), as compared to low (0.28 Hz and 26%; POR 3.5). We found no consistent and significant effect of muscular load, on either neck or shoulder disorders. However, selection and other bias may have diminished our possibility to observe such effects. Psychosocial work environment factors were not confounding the results. Measurements of wrist movements may be used for identification of high-risk work tasks.

Lowered birth weight among infants born to women with a high intake of fish contaminated with persistent organochlorine compounds

In Sweden fatty fish from the Baltic Sea (at the Swedish east coast) constitute the main exposure route for persistent organochlorine compounds (POC). The present study assessed reproductive outcomes among fishermen's sisters from the Swedish east coast, who were shown to had had a relatively high consumption of contaminated fish in early life. For relevant comparison, we used a similar cohort from the Swedish west coast, where the contamination of fish is considerable less. The east coast cohort women had an increased risk of having an infant with low birth weight (LBW; <2500 g) as compared with the west coast cohort women (odds ratio (OR) 1.6. 95% confidence interval 1.1-2.3). The results strengthen the hypothesized association between exposure to POC during childhood and adolescence and an increased risk for LBW.

Miscarriages and stillbirths in women with a high intake of fish contaminated with persistent organochlorine compounds

OBJECTIVES

The purpose of the present study was to assess the effect, on miscarriages and stillbirths, of persistent organochlorine compounds (POC) through dietary intake of fatty fish from the Baltic Sea.

METHODS

Information on miscarriages and stillbirths was collected retrospectively by a self-administered questionnaire in a cohort of fishermen's wives from the Swedish east coast (by the Baltic Sea) and in a referent cohort of west coast fishermen's wives. Current fish consumption was used as a proxy for exposure within the east coast cohort.

RESULTS

No increase in miscarriages or stillbirths was found in the east coast cohort compared with the west coast group, in fact a decrease in early miscarriages was found (OR 0.48 [95% CI 0.26-0.92]). Moreover, no increase in risk was found for current high consumers of fatty fish within the east coast cohort.

CONCLUSIONS

The present data provided no evidence that dietary POC exposure increases miscarriage and stillbirth rates.

Musculoskeletal disorders among female dental personnel--clinical examination and a 5-year follow-up study of symptoms

OBJECTIVES

To explore the natural course of musculoskeletal disorders during a 5-year period among dental personnel, to survey findings and diagnoses according to a standardized protocol, and to compare and evaluate different methods for the detection of musculoskeletal disorders in a population.

METHODS

In a 5-year follow-up study, dental personnel (n = 90) and referents (n = 30) were studied. The Nordic questionnaire (years 0 and 5), the present pain rating according to the Borg category ratio scale, and physical examination (year 5) were used.

RESULTS

In year 0 the prevalence of symptoms in the shoulders, the wrists/hands, and, unexpectedly, the hips was higher in the dental personnel as compared with the referents. Furthermore, those (16%) who had left the dental profession during the observation period showed a higher prevalence of and, often, combined symptoms from several body regions in year 0 than did those who stayed. Dental personnel who remained in the profession tended to have an increased risk of developing more symptoms in the shoulders and the elbows/wrists/hands in year 5 as compared with year 0 and at year 5 were in more pain and had received more diagnoses for the neck/shoulder region relative to the referents. Furthermore, there was a considerable variation in symptoms during the follow-up period. The sensitivity of the pain rating and of the Nordic questionnaire in detecting musculoskeletal disorders was high for the neck and shoulders but was not as high for the elbow, wrists/hands, or hips. The association was better for diagnoses than for findings. The opposite patterns were observed for specificity.

CONCLUSIONS

Dental personnel had an increased risk of developing musculoskeletal disorders as verified by symptoms and diagnoses and more painful or persistent conditions. This led to a selection out of work. The questionnaire and the present pain rating gave a relatively good picture of the prevalence of musculoskeletal disorders arising from the neck, shoulders, and hips and would be useful as screening tools. Their sensitivity in detecting disorders was higher for diagnoses than for findings. However, these methods were not as sensitive for disorders involving the elbows/wrists/hands. Physical examinations gave more detailed information.

Fish processing work: the impact of two sex dependent exposure profiles on musculoskeletal health

OBJECTIVES

To evaluate the impact of work tasks, physical exposure, and psychosocial factors on the risk of musculoskeletal disorders in men and women, in a defined industrial setting.

METHODS

116 male and 206 female fish industry workers were compared with 129 men and 208 women with more varied work. Physical and psychosocial work load as well as musculoskeletal complaints were recorded by a questionnaire. A physical examination was performed and an observation method was used for work evaluation. 196 male and 322 female former fish processing workers received a postal questionnaire.

RESULTS

The women workers in the fish industry had worse working conditions than the men for repetitiveness, constrained neck postures, and psychosocial work environment. They also had higher prevalences of complaints of the neck and shoulder (prevalence odds ratio (POR) 1.9; 95% confidence interval (95% CI) 1.1 to 3.2), neck and shoulder and elbow and hand complaints (POR 2.9; 95% CI 1.8 to 4.7 and POR 2.8; 95% CI 1.6 to 4.7, respectively). The women more often than the men left the industry because of neck and upper limb complaints. Also, women in other work had a higher prevalence of complaints of the neck and shoulder (POR 2.3; 95% CI 1.1 to 5.1) than the men. The men in the fish processing industry had a higher prevalence of complaints of the neck and shoulder than the men in other work (POR 3.6; 95% CI 1.6 to 8.0). This difference was not shown up by the questionnaire.

CONCLUSIONS

Despite superficially similar work, there were clear sex differences in physical exposure and psychosocial work environment. Work in the fish processing industry was associated with a high risk of neck and upper limb disorders in women, which was probably mainly due to their extremely repetitive work tasks; the corresponding men had less repetitive work and less disorders. Also, a healthy worker effect on neck and upper limb disorders was found. The advantage of a physical examination compared with a questionnaire is clearly shown.

No evidence for congenital malformations or prenatal death in infants born to women with a high dietary intake of fish contaminated with persistent organochlorines

OBJECTIVES

The aim of the present study was to assess whether a high dietary intake of fatty fish from the Baltic Sea, contaminated with persistent organochlorine compounds, might increase the risk for congenital malformations and perinatal death.

METHODS

A cohort of fishermen's wives from the Swedish east coast (at the Baltic Sea) were linked to the Swedish Medical Birth Register (MBR), resulting in the identification of 1501 infants born in the period 1973-1991. A further linkage with the Swedish Registry of Congenital Malformations was performed. Similar linkages were made for a comparison group of fishermen's wives from the Swedish west coast, who gave birth to 3553 infants during the study period. The reproductive end points studied included congenital malformations, stillbirths, and early neonatal deaths. The expected numbers of these end points were calculated from the MBR data for the regional populations.

RESULTS

In the east coast cohort, 3.3% of the infants had some malformation diagnosis as compared with 5.0% of the west coast cohort. As compared with the general population, somewhat fewer malformations than expected were diagnosed in the east coast cohort (risk ratio 0.78, 95% CI 0.58-1.04). No specific malformation was overrepresented in the east coast cohort. The risk ratios for stillbirths and early neonatal deaths did not significantly differ from unity in any of the cohorts.

CONCLUSIONS

The present results exclude in an unequivocal way an association between exposure to persistent organochlorines from fatty Baltic Sea fish and an increased risk for all congenital malformations and perinatal death. The limited power of the study design, however, does not allow the exclusion of slight risk excesses for some specific types of malformation.

Polychlorinated biphenyls in blood plasma among Swedish female fish consumers in relation to low birth weight

The authors examined the hypothesized association between the body burden of polychlorinated biphenyls (PCB) in women and the risk of low birth weight for their infants. In Sweden, a main exposure route for PCBs and other persistent organochlorine compounds is through the consumption of fatty fish from the Baltic Sea (on the Swedish east coast). A previous comparison between a cohort of consumers of large quantities of fish from the Swedish east coast and a reference population, together with a following analysis based on questionnaire data from a case-control study within the east coast cohort, supported the hypothesized association. In 1995, blood samples were collected from the wives and ex-wives of fishermen from the Swedish east coast (n = 192) who had given birth during the period 1973-1991. Cases (n = 57), i.e., infants with low birth weight (1,500-2,750 g), were matched with controls (n = 135; birth weight, 3,250-4,500 g) on gender, parity, and calendar year of birth. The concentration of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma was analyzed; it has been suggested that CB-153 is a relevant biomarker of exposure to PCBs. The concentration of CB-153 in the plasma of mothers during the year of childbirth was "estimated" using some alternative plausible kinetic models. For two alternative estimated exposure datasets, which were focused on separately, an increase in the risk of a low birth weight was observed at a CB-153 concentration of 300 and 400 ng/g lipid weight, respectively (adjusted odds ratios of 2.1 (95% confidence interval (CI) 1.0-4.7) and 2.3 (95% CI 0.9-5.9)). The present results strengthen the findings reported previously for this study population.

Agreement between reported fish consumption obtained by two interviews and its impact on the results in a reproduction study

In an ongoing study of the hypothesised association between consumption of fish contaminated with persistent organochlorine compounds and low birth weight, a relevant measure of exposure is the accumulated fish consumption over long time periods. An issue of concern in this study is the quality of the retrospective exposure assessments. The present investigation was undertaken to determine the agreement between reported fish consumption in two interviews with approximately one year in between. in order to evaluate its impact on the effect estimates. The agreement decreased with increasing retrospective time interval between interview and focused time period of fish consumption. Furthermore, the exposure assessments based on the two interviews led to considerably different effect estimates.

Airway symptoms and lung function in pipelayers exposed to thermal degradation products from MDI-based polyurethane

OBJECTIVES

To study the prevalence of symptoms from the eyes and the upper and lower respiratory tract, lung function, and immunological sensitisation towards isocyanates in pipelayers exposed to thermal degradation products from methylene diphenyl diisocyanate (MDI)-based polyurethane (PUR).

MATERIAL AND METHODS

50 presently active and 113 formerly active pipelayers were examined. Also, 65 unexposed workers were investigated for comparison. The one year prevalence of symptoms and smoking history (questionnaire data), lung function (vital capacity (VC) and forced expiratory volume in one second (FEV1), and atopy (positive skin prick tests towards standard allergens) were assessed among pipelayers and controls. For the pipelayers, the presence of work related symptoms and estimates of isocyanate and welding exposure were obtained from an interview. Skin prick tests towards specific isocyanate antigens and determinations of IgE-MDI and IgG-MDI in serum were also performed.

RESULTS

The prevalence of episodes (more than once a month) of irritative eye symptoms, congestion of the nose, and soreness or dryness in the throat was much higher among the PUR pipelayers than among the controls. Most of the pipelayers with symptoms reported that these had started and occurred in relation to the PUR welding tasks. Presently active pipelayers with recent high PUR exposure showed a significant reduction of FEV1 compared with the controls. The estimated reduction, adjusted for smoking, was -0.3 l (P = 0.04). There was no confounding effect of ordinary welding. None of the pipelayers showed positive skin prick reactions against the specific isocyanate antigens used, or positive IgE-MDI, and only two had increased IgG-MDI.

CONCLUSIONS

The findings indicate that exposure to thermal degradation products from MDI-based polyurethane has adverse effects on the mucous membranes and airways.

The impact of age, lactation and dietary habits on PCB in plasma in Swedish women

The mean concentration of the chlorinated biphenyl 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma from 192 fishermen's wives from the Swedish east coast was on a fresh weight basis 960 (range 80-4300) pg/g and lipid adjusted 160 (range 20-780) ng/g lipid. The concentration of CB-153 in plasma was significantly influenced by age, total lactation time and place of living during childhood and adolescence (fishing village vs. other place). The residential variable probably reflects early life consumption of fish from the Baltic Sea (at the Swedish east coast) contaminated with persistent organochlorine compounds.

Monitoring of polychlorinated biphenyls in human blood plasma: methodological developments and influence of age, lactation, and fish consumption

Human plasma samples from 50 wives of fishermen have been analyzed with respect to PCBs. The non-ortho-substituted PCB congeners CB-126 and CB-169 were determined by mass spectrometry in negative ion chemical ionization mode, which demonstrated a limit of detection of 30 fg. The recoveries of the internal standards used for determination of ortho-substituted CBs were approximately 95%. Two methods, one gravimetric and the other based on enzymatic determinations of triglycerides, cholesterol and phospholipids, were compared for the determination of total amount of lipids in the plasma samples; the correlation coefficient was 0.82 and the slope 0.98. For practical reasons, enzymatic determinations are recommended for further use. The total, lipid-adjusted concentrations of PCBs in plasma were influenced by age, total lactation time and consumption of fatty fish from the Baltic Sea.