Organic dust is associated with adverse effects on human airways. This study was done to investigate whether the addition of beta-(1,3)-D glucan or aldehydes to office dust causes enhanced inflammation in human airways.
Thirty-six volunteers were exposed randomly to clean air, office dust, dust spiked with glucan, and dust spiked with aldehydes. The three dust exposures contained between 332 and 379 microg dust/m(3). Spiking with 1 gram of dust was done with 10 milligrams of glucan or 0.1 microliters of aldehydes. Acoustic rhinometry, rhinostereometry, nasal lavage, and lung function tests were applied.
After the exposures to dust spiked with the glucan and aldehydes, the nasal volume decreased (-1.33 and -1.39 cm(3) (mean), respectively) when compared with the -0.9 cm(3) after clean air or office dust (P=0.036 for a difference in decrease between exposures). After 2-3 hours the aldehyde-spiked dust caused a 0.6-mm swelling of the inferior turbinate, and glucan-spiked dust produced a 0.7-mm swelling (P=0.039 for a difference in the swelling between the four exposures). The preexposure nasal lavage cleaned off the mucosa, and lower cytokine concentrations were found after all of the exposures. For interleukin-8, this decrease in concentration was smaller after the dust exposures spiked with glucan and aldehydes (-2.9 and -25.8 pg/ml, respectively) than after office dust or clean air (-65.9 and -74.1 pg/ml, respectively) (P=0.042). The nasal eosinophil cell concentration increased after exposure to dust spiked with glucan (P=0.045).
beta-(1,3)-D glucan and aldehydes in office dust enhance the inflammatory effects of dust on the upper airways.
The number of children in daycare centers (DCCs) is rising. This increases exposure to microorganisms and infectious diseases. Little is known about which bacteria and viruses are present in the DCC environment and where they are located. In the study described in this article, the authors set out to determine the prevalence of pathogenic bacteria and viruses and to find the most contaminated fomites in DCCs. Fifteen locations in each DCC were sampled for bacteria, respiratory viruses, and gastrointestinal viruses. The locations were in the toilet, kitchen, and playroom areas and included nursery pillows, toys, and tables, among other things. Coliform bacteria were primarily found in the toilet and kitchen areas whereas nasopharyngeal bacteria were found mostly on toys and fabric surfaces in the playroom. Respiratory viruses were omnipresent in the DCC environment, especially on the toys.
Multi-component interventions combining educational and environmental strategies have proved effective in increasing children and adolescents' fruit and vegetable intake. However such interventions are complex and difficult to implement and several studies report poor implementation. There is a need for knowledge on the role of dose for behaviour change and for assessment of intervention dose to avoid conclusions that intervention components which are not implemented are ineffective. This study aimed to examine 1) the association between dose of a class curriculum and adolescents' fruit and vegetable intake in a school-based multi-component intervention, 2) if gender and socioeconomic position modify this association.
We carried out secondary analysis of data from intervention schools in the cluster-randomized Boost study targeting 13-year-olds' fruit and vegetable intake. Teacher- and student data on curriculum dose delivered and received were aggregated to the school-level and class-level (only possible for student data). We analysed the association between curriculum dose and students' (n 995) self-reported fruit and vegetable intake (24-h recall questionnaire) after finalization of the intervention using multi-level analyses. Potential moderation was examined by analyses stratified by gender and socioeconomic position.
Average dose received at class-level was significantly associated with students' fruit and vegetable intake (10 g (CI: 0.06, 20.33) per curricular activity received). In stratified analyses the association remained significant among boys only (14 g (CI: 2.84, 26.76) per curricular activity received). The average dose delivered and received at the school-level was not significantly associated with students' intake.
We found a dose-response relationship between number of curricular activities received and adolescents' fruit and vegetable intake. The results indicate that curriculum dose received only mattered for promotion of fruit and vegetable intake among boys. Future studies should explore this gender difference in larger samples to guide the planning of school-based curricular interventions with regards to the optimal number of curricular activities required to promote behavioural change in subgroups with low fruit and vegetable intake at baseline.
Adverse health effects of exposure to high levels of air pollutants from biodegradable wastes have been well-studied. However, few investigations have examined the potential effects of chronic exposure to low-to-moderate levels on non-specific health symptoms among residents. Besides, most studies have relied on distances to waste sites to assign exposure status, and have not investigated whether the exposure-symptoms associations are direct or mediated by odor annoyance. In this study, individual-level exposures to a proxy indicator of biodegradable waste pollution (ammonia, NH3) in non-urban residences (n=454) during 2005-2010 were characterized by data from emission-dispersion validated models. Logistic regression and mediating analyses were used to examine associations between exposures and questionnaire-based data on annoyance and non-specific symptoms, after adjusting by person-specific covariates. Strong dose-response associations were found between exposures and annoyance, and between annoyance and symptoms. Associations between exposures and symptoms (nausea, headache, dizziness, difficulty concentrating and unnatural fatigue) were indirect (annoyance-mediated). This study indicates that environmental exposures play an important role in the genesis of non-specific symptoms among residents exposed to low-to-moderate air pollution from biodegradable wastes, although the effects seem to be indirect, relayed through stress-related mechanisms.
Perfluorinated alkylated substances (PFAS) have been extensively used in consumer products and humans are widely exposed to these persistent compounds. A recent study found no association between exposure to perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) and miscarriage, but no studies have examined adverse effect of the more recently introduced PFASs. We therefore conducted a case-control study within a population-based, prospective cohort during 2010-2012. Newly pregnant women residing in the Municipality of Odense, Denmark were invited to enroll in the Odense Child Cohort at their first antenatal visit before pregnancy week 12. Among a total of 2,874 participating women, 88 suffered a miscarriage and 59 had stored serum samples, of which 56 occurred before gestational week 12. They were compared to a random sample (N=336) of delivering women, who had also donated serum samples before week 12. Using a case-control design, 51 of the women suffering a miscarriage were matched on parity and gestational day of serum sampling with 204 delivering women. In a multiple logistic regression with adjustment for age, BMI, parity and gestational age at serum sampling, women with the highest tertile of exposure to perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) in pregnancy had odds ratios for miscarriage of 16.5 (95% CI 7.4-36.6-36.5) and 2.67 (1.31-5.44), respectively, as compared to the lowest tertile. In the matched data set, the OR were 37.9 (9.9-145.2) and 3.71 (1.60-8.60), respectively. The association with perfluorohexane sulfonic acid (PFHxS) was in the same direction, but not statistically significant, while no association was found with PFOA and PFOS. Our findings require confirmation due to the possible public health importance, given that all pregnant women are exposed to these widely used compounds.
This study investigates the potential health risk from urban gardening. The concentrations of the trace elements arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn) in five common garden crops from three garden sites in Copenhagen were measured. Concentrations (mg/kg dw) of As were 0.002-0.21, Cd 0.03-0.25, Cr
Solar ultraviolet radiation (UVR) is known to be the most important etiological factor in skin cancer development. The main objective of this thesis was to achieve an objective, basic knowledge of the individual UVR exposure dose pattern and to reveal the factors and with which power they influence on the UVR dose among the Danes. Eight open prospective, observational studies and one study analyzing the compliance and reliability of data were performed in healthy Danish volunteers with an age range of 4-68 years. The subjects were chosen to cover an age span group of children, adolescents, and indoor workers and in addition, groups with expected high UVR exposure, sun worshippers, golfers, and gardeners. We developed a personal, electronic UVR dosimeter in a wristwatch (SunSaver). The subjects wore the UVR dosimeter that measured time-stamped UVR doses in standard erythema doses (SED) and completed diaries with data on their sun exposure behaviour. This resulted in corresponding UVR dosimeter and diary data from 346 sun-years where one sun-year is one person participating in one summer half-year (median 119 days). The annual UVR doses were calculated based on the personal and ambient measured UVR doses. We found a huge variation in annual UVR exposure dose within the total population sample, median 173 SED (range, 17-980 SED). The inter-group variation in annual UVR dose was from median 132 SED among indoor workers to median 224 SED among gardeners. No significant correlation was found between annual UVR dose and age either within the total population or among the adults. But the subjects below 20 years of age had an increase in annual UVR dose of 5 SED per year. Young people before the age of 20 years did not get a higher proportion of the lifetime UVR dose than expected (25%) when assuming a life expectancy of 80 years. There was no significant difference in annual UVR dose between males and females in the total population sample. But, among children, girls received a significantly higher UVR dose than boys due to more days with risk behaviour (sunbathing or exposing shoulders outdoors). This exposure pattern, with females having more risk behaviour than males, was also found among adolescents and adults. Sunbathing or exposing shoulders (risk behaviour) outside the beach resulted in a median of 2.5 SED per day in northern Europe and 3.2 SED per day in southern Europe, while the corresponding values were 4.6 SED and 6.9 SED per day at the beach. UVR doses above 10 SED per day were connected with risk behaviour. The subjects had a median of 13 days with risk behaviour (range, 0-93 days). The subjects used sunscreen on a median of five days (range, 0-130 days), but have a median of seven days with risk behaviour without sunscreen applied (range, 0-47 days). They had a median of one sunburn per sun-year (range 0-10). Fifty percent of the UVR dose was received between 12.00 and 15.00. Only the gardeners received the main part of their UVR dose on workdays. Conclusions : - High UVR doses are connected with risk behaviour. Reduction of cumulative lifetime UVR dose could be obtained by minimizing risk behaviour. - Sunburns were highly correlated to risk behaviour. - Use of sunscreen correlated with days "sunbathing with the intention to tan", indicating that sunscreens were used to avoid sunburn during risk behaviour. - Scheduling lunch breaks and other breaks indoors at noon, where ambient UVR peaks, could reduce the occupational UVR exposure significantly. - In the winter-half-year in Denmark. the UVR dose received from solar exposure is negligible and no UVR precautions are needed. This study documented that high subject compliance rate and data reliability could be obtained in long-time UVR dosimeter study as ours by being service minded but persistent, offering dosimeter maintenance service within 24 hours and scrutinizing data for errors and mistakes just after data collection.
BACKGROUND: Much environmental health research depends on human volunteers participating with biological samples. The perception study explores why and how people participate in a placenta perfusion study in Copenhagen. The participation implies donation of the placenta after birth and some background information but no follow up. METHODS: Nineteen semi-structured qualitative interviews were conducted with participants in the placenta perfusion study after donation of placenta. Observation studies were made of recruitment sessions. RESULTS: The interviewed participants are generally in favour of medical research. They participated in the placenta perfusion study due to a belief that societal progress follows medical research. They also felt that participating was a way of giving something back to the Danish health care system. The participants have trust in medical science and scientists, but trust is something which needs to be created through "trust-work". Face-to-face interaction, written information material and informed consent forms play important parts in creating trusting relationships in medical research. CONCLUSION: Medical research ethics do not only amount to specific types of written information material but should also be seen as a number of trust making performances involving researchers as well as research participants.
Perfluorooctanoate (PFOA) has been associated with impaired lactation in mice. We examined whether maternal perfluorooctanesulfonate (PFOS) and PFOA concentrations correlated with duration of breastfeeding among women.
We randomly selected 1400 pregnant women from the Danish national birth cohort (1996-2002) and measured PFOS and PFOA concentrations in early pregnancy by using high performance liquid chromatography/tandem mass spectrometry. Self-reported data on the duration of any and exclusive breastfeeding were collected twice during telephone interviews around 6 and 18 months after the birth of the child.
The duration of breastfeeding decreased with increasing concentrations of pregnancy PFOS and PFOA among multiparous women, for whom the adjusted odds ratios (OR) for weaning before 6 months of age were 1.20 (95% CI 1.06-1.37) per 10 ng/ml increase in PFOS concentrations and 1.23 (95% CI 1.13-1.33) per 1 ng/ml increase in PFOA concentrations. No consistent association was found for primiparous women.
These findings suggest that PFOA and PFOS may reduce the ability to lactate, but could equally reflect reverse causation since no association was seen in primiparous women.
Exposure to traffic noise has been associated with adverse effects on neuropsychological outcomes in children, but findings with regard to behavioral problems are inconsistent.
We investigated whether residential road traffic noise exposure is associated with behavioral problems in 7-year-old children.
We identified 46,940 children from the Danish National Birth Cohort with complete information on behavioral problems at 7 years of age and complete address history from conception to 7 years of age. Road traffic noise (Lden) was modeled at all present and historical addresses. Behavioral problems were assessed by the parent-reported Strengths and Difficulties Questionnaire (SDQ). Associations between pregnancy and childhood exposure to noise and behavioral problems were analyzed by multinomial or logistic regression and adjusted for potential confounders.
A 10-dB increase in average time-weighted road traffic noise exposure from birth to 7 years of age was associated with a 7% increase (95% CI: 1.00, 1.14) in abnormal versus normal total difficulties scores; 5% (95% CI: 1.00, 1.10) and 9% (95% CI: 1.03, 1.18) increases in borderline and abnormal hyperactivity/inattention subscale scores, respectively; and 5% (95% CI: 0.98, 1.14) and 6% (95% CI: 0.99, 1.12) increases in abnormal conduct problem and peer relationship problem subscale scores, respectively. Exposure to road traffic noise during pregnancy was not associated with child behavioral problems at 7 years of age.
Residential road traffic noise in early childhood may be associated with behavioral problems, particularly hyperactivity/inattention symptoms.
Cites: Lancet. 2005 Jun 4-10;365(9475):1942-915936421
BACKGROUND: The development of obesity is still a poorly understood process that is dependent on both genetic and environmental factors. OBJECTIVE: The objective was to examine how physical activity and the proportion of energy as protein in the diet modify the genetic variation of body mass index (BMI), waist circumference, and percentage body fat. DESIGN: Twins from Denmark (756 complete pairs) and Finland (278 complete pairs) aged 18-67 and 21-24 y, respectively, participated. The proportion of energy as protein in the diet was estimated by using food-frequency questionnaires. The participants reported the frequency and intensity of their leisure time physical activity. Waist circumference and BMI were measured. Percentage body fat was assessed in Denmark by using a bioelectrical impedance method. The data were analyzed by using gene-environment interaction models for twin data with the Mx statistical package (Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA). RESULTS: High physical activity was associated with lower mean values, and a high proportion of protein in the diet was associated with higher mean BMI, waist circumference, and percentage body fat and a reduction in genetic and environmental variances. Genetic modification by physical activity was statistically significant for BMI (-0.18; 95% CI: -0.31, -0.05) and waist circumference (-0.14; 95% CI: -0.22, -0.05) in the merged data. A high proportion of protein in the diet reduced genetic and environmental variances in BMI and waist circumference in Danish men but not in women or in Finnish men. CONCLUSIONS: Our results suggest that, in physically active individuals, the genetic variation in weight is reduced, which possibly suggests that physical activity is able to modify the action of the genes responsible for predisposition to obesity, whereas the protein content of the diet has no appreciable effect.
BACKGROUND: Adverse psychosocial work environments may lead to impaired mental health, but it is still a matter of conjecture if demonstrated associations are causal or biased. We aimed at verifying whether poor psychosocial working climate is related to increase of redeemed subscription of antidepressant medication. METHODS: Information on all antidepressant drugs (AD) purchased at pharmacies from 1995 through 2006 was obtained for a cohort of 21,129 Danish public service workers that participated in work climate surveys carried out during the period 2002-2005. Individual self-reports of psychosocial factors at work including satisfaction with the work climate and dimensions of the job strain model were obtained by self-administered questionnaires (response rate 77,2%). Each employee was assigned the average score value for all employees at his/her managerial work unit [1094 units with an average of 18 employees (range 3-120)]. The risk of first-time AD prescription during follow-up was examined according to level of satisfaction and psychosocial strain by Cox regression with adjustment for gender, age, marital status, occupational status and calendar year of the survey. RESULTS: The proportion of employees that received at least one prescription of ADs from 1995 through 2006 was 11.9% and prescriptions rose steadily from 1.50% in 1996 to the highest level 6.47% in 2006. ADs were prescribed more frequent among women, middle aged, employees with low occupational status and those living alone. None of the measured psychosocial work environment factors were consistently related to prescription of antidepressant drugs during the follow-up period. CONCLUSION: The study does not indicate that a poor psychosocial work environment among public service employees is related to prescription of antidepressant pharmaceuticals. These findings need cautious interpretation because of lacking individual exposure assessments.
Socioeconomic differences in morbidity and mortality, particularly across educational groups, are widening. Differential exposures to behavioural risk factors have been shown to play an important mediating role on the social inequality in chronic diseases such as heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, and lung cancer. However, much less attention has been given to the potential role of interaction, where the same level of exposure to a behavioural risk factor has different effect across socioeconomic groups, creating subgroups that are more vulnerable than others. In this thesis, Paper 1 describes the unique cohort consortium which was established by pooling and harmonising prospective data from existing cohort studies in Denmark. This consortium generated a large study population with long follow-up sufficient to study power demanding questions of mechanisms underlying social inequalities in chronic disease outcomes. In Paper 2 on incidence of coronary heart disease, smoking and body mass index partially mediated the observed educational differences. This result suggested that some of the social inequality in coronary heart disease may be enhanced by differential exposure to behavioural risk factors (i.e. smoking and obesity). In Paper 3 on incidence of stroke, an observed interaction between education and smoking indicated that participants, particularly men, with low level of education may be more vulnerable to the effect of smoking than those with high level of education in terms of ischemic stroke. Finally, Paper 4 revealed that behavioural risk factors, primarily smoking, explained a considerable part of the educational differences in cause-specific mortality. Further, this paper added important knowledge about the considerable part of the mediated effect, which could be due to interaction between education and smoking. In conclusion, the research in this thesis is a practical implementation of contemporary statistical methodology, the additive hazards models, in which the potential role of behavioural risk factors can be regarded not only as mediation but also as interaction with the effect of socioeconomic position on chronic disease outcomes. The results support that two central mechanisms, differential exposure and differential vulnerability to behavioural risk factors, particularly smoking; have contributed substantially to the social inequality in chronic disease outcomes in Denmark. These mechanism are not mutually exclusive and should be regarded simultaneously. However, the findings could be non-causal associations due to, for instance, psychosocial or environmental factors. Nevertheless, research on social inequality in chronic disease outcomes should regard not only that the smoking prevalence is higher in lower socioeconomic groups (differential exposure), but also that health consequences of being a smoker seem to be worse in these subgroups (differential vulnerability).
Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender differences in children's perceptions of barriers to recess physical activity. Based on the socio-ecological model four types of environmental barriers were distinguished: natural, social, physical and organizational environment.
Data were collected through 17 focus groups (at 17 different schools) with in total 111 children (53 boys) from fourth grade, with a mean age of 10.4 years. The focus groups included an open group discussion, go-along group interviews, and a gender segregated post-it note activity. A content analysis of the post-it notes was used to rank the children's perceived barriers. This was verified by a thematic analysis of transcripts from the open discussions and go-along interviews.
The most frequently identified barriers for both boys and girls were weather, conflicts, lack of space, lack of play facilities and a newly-found barrier, use of electronic devices. While boys and girls identified the same barriers, there were both inter- and intra-gender differences in the perception of these barriers. Weather was a barrier for all children, apart from the most active boys. Conflicts were perceived as a barrier particularly by those boys who played ballgames. Girls said they would like to have more secluded areas added to the school playground, even in large schoolyards where lack of space was not a barrier. This aligned with girls' requests for more "hanging-out" facilities, whereas boys primarily wanted activity promoting facilities.
Based on the results from this study, we recommend promoting recess physical activity through a combination of actions, addressing barriers within the natural, social, physical and organizational environment.
Cites: BMC Public Health. 2011;11:46121663605
Cites: J Bone Miner Res. 2007 Jan;22(1):101-917014381
Cites: J Sci Med Sport. 2012 Jan;15(1):44-5121940211
Cites: Health Educ Res. 2012 Apr;27(2):269-8021712499
Methylmercury, polychlorinated biphenyls (PCBs), and perfluorinated compounds (PFCs) are ubiquitous and persistent environmental chemicals with known or suspected toxic effects on the nervous system and the immune system. Animal studies have shown that tissue damage can elicit production of autoantibodies. However, it is not known if autoantibodies similarly will be generated and detectable in humans following toxicant exposures. Therefore, we conducted a pilot study to investigate if autoantibodies specific for neural and non-neural antigens could be detected in children at age 7 years who have been exposed to environmental chemicals. Both prenatal and age-7 exposures to mercury, PCBs, and PFCs were measured in 38 children in the Faroe Islands who were exposed to widely different levels of these chemicals due to their seafood-based diet. Concentrations of IgM and IgG autoantibodies specific to both neural (neurofilaments, cholineacetyltransferase, astrocyte glial fibrillary acidic protein, and myelin basic protein) and non-neural (actin, desmin, and keratin) antigens were measured and the associations of these autoantibody concentrations with chemical exposures were assessed using linear regression. Age-7 blood-mercury concentrations were positively associated with titers of multiple neural- and non-neural-specific antibodies, mostly of the IgM isotype. Additionally, prenatal blood-mercury and -PCBs were negatively associated with anti-keratin IgG and prenatal PFOS was negatively associated with anti-actin IgG. These exploratory findings demonstrate that autoantibodies can be detected in the peripheral blood following exposure to environmental chemicals. The unexpected association of exposures with antibodies specific for non-neural antigens suggests that these chemicals may have toxicities that have not yet been recognized.
Cites: Exp Cell Res. 2004 Nov 15;301(1):1-715501438
Cites: J Toxicol Environ Health A. 2007 Nov;70(21):1873-717934961
This report reviews current literature regarding the association of the pharmaceutical preservative thimerosal and other mercury exposures with the risk for autism. The evidence presented here does not support a causal association between autism and mercury exposure from the preservative thimerosal. The risk for autism from other mercury exposures such as from dental amalgam restorations or environmental mercury release into the atmosphere is ambiguous. Since mercury is a known neurotoxin, more research should be done to ensure that mercury exposure from any source does not contribute to autism.
Brominated flame retardants (BFRs), in particular the polybrominated diphenyl ethers (PBDEs), have been used in consumer products for many years to increase fire resistance. Recently, developmental neurotoxicity at very low levels has increased the concern about these compounds. The major objectives of this study were to investigate the maternal and fetal exposure to PBDEs on the basis of maternal and umbilical cord plasma samples and to study the extent of placental transfer for different PBDE congeners. The findings were also compared with previously observed PBDE levels and patterns determined in placental tissue from the same individuals, and the relationship with the external exposure from house dust from the participants' homes was explored. Samples of maternal and umbilical cord plasma from a cohort of 51 pregnant women from the Copenhagen area were collected. Paired maternal and umbilical cord plasma were analysed for BDE-28, 37, 47, 85, 99, 100, 119, 138, 153, 154, 183, 209 and the brominated biphenyl BB-153 using automated SPE extraction and GC-HRMS for the tri- to hepta-BDEs and GC-LRMS (ECNI) for BDE-209. PBDEs were detected in all maternal and umbilical cord plasma samples. The sum of tri- to hexa-BDEs (SigmaPBDE) in maternal plasma varied between 640 and 51,946 pg/g lipid weight (lw) with a median level of 1765 pg/g lw. In the umbilical cord samples SigmaPBDE varied between 213 and 54,346 pg/g lw with a median of 958 pg/g lw. The levels observed in fetal and maternal plasma were highly correlated, but the placental transport of PBDE congeners was found to decrease with increasing diphenyl ether bromination. Maternal concentrations were significantly correlated (p
BACKGROUND: The role of genetic and environmental factors for developing alexithymia is still unclear, and the aim of this study was to examine these factors in a large population-based sample of twins. METHODS: The Toronto Alexithymia Scale-20 (TAS-20) was included in a mail survey of 46,418 individuals born between 1931 and 1982 and registered with the Danish Twin Registry. The response rate was 75.3%. A total of 8,785 twin pairs, where both cotwins had completed all items of the TAS-20, were selected for this study. Analyses were conducted for total TAS-20 scores and the subscales of (1) difficulties in identifying feelings, (2) difficulties in describing feelings, and (3) externally oriented thinking. The phenotypes were analyzed both as categorical and continuous data. RESULTS: All measures of similarity suggested that genetic factors added to all facets of alexithymia. Structural equation modeling of the noncategorical data, an ACE model including additive genetic, shared environmental and nonshared environmental effects, provided the best fit for all three facets of alexithymia as well as total alexithymia scores, with heritabilities of 30-33% and the remaining variance being explained by shared (12-20%) and nonshared environmental effects (50-56%). CONCLUSION: The results from this large population-based sample suggest that genetic factors have a noticeable and similar impact on all facets of alexithymia. While the results suggested a moderate influence of shared environmental factors, our results are in concordance with the general finding that environmental influences on most psychological traits are primarily of the nonshared rather than the shared type.