Prevalence of Autism Spectrum Disorder in 7-9-Year-Old Children in Denmark, Finland, France and Iceland: A Population-Based Registries Approach Within the ASDEU Project.

We estimated autism spectrum disorder (ASD) prevalence in 7-9 year-old children in 2015 using data from three nationwide health registry systems (Denmark, Finland, Iceland) and two French population-based regional registries. Prevalence ranged from 0.48% in South-East France to 3.13% in Iceland (South-West France: 0.73%, Finland: 0.77%, Denmark: 1.26%). Male/female ratios ranged from 3.3 in Finland to 5.4 in South-West France. Between 12% (Denmark) and 39% (South-West France) of cases were diagnosed with intellectual disability. The variations in population-based ASD prevalence across four European countries with universal health care practices likely reflect variation in detection, referral and diagnosis practices and autism awareness across these areas. Using established population-based data systems is an efficient approach to monitor ASD prevalence trends over time.

Mortality of the users of a hospital emergency department.

OBJECTIVE: To ascertain the annual number of users who were discharged home after visits to the emergency department (ED), grouped by age, sex, and number of visits during the calendar year, and to assess whether a higher number of visits to the department predicted a higher mortality. METHODS: This was a retrospective cohort study, with follow up of cause specific mortality through a national registry, in the Reykjavik area of Iceland. In total, 19 259 patients who visited the ED during the period 1995-2001 and who were discharged home at the Landspítali University Hospital, Reykjavik, Iceland, were enrolled. The main outcome measures were the standardised mortality ratio, with expected number based on national mortality rates, and hazard ratio calculations using time dependent multivariate regression analysis. RESULTS: The annual increase in visits to the ED among the patients discharged home was 7-14% per age group during the period 1995-2001, with the highest increase among older men. When emergency department users were compared with the general population, the standardised mortality ratio was 1.81 for men and 1.93 for women. Among those attending the ED two, three, or more times in a calendar year, the mortality rate was higher than among those coming only once in a year. The causes of death that led to the highest mortality among frequent users of the ED were neoplasm, ischaemic heart diseases, and external causes, particularly drug intoxication, suicides, and probable suicides. CONCLUSIONS: The mortality of those who had used the ED and been discharged home was found to be higher than that of the general population. Frequent users of the ED had a higher mortality than those visiting the department no more than once a year. As the ED serves general medicine and surgery patients, not injuries, the high mortality due to drug intoxication, suicide, and probable suicide is interesting. Further studies are needed into the diagnosis at discharge of those frequently using the ED, in an attempt to understand and possibly prevent this marked mortality rate.

Cosmic radiation and cancer mortality among airline pilots: results from a European cohort study (ESCAPE).

Cosmic radiation is an occupational risk factor for commercial aircrews. In this large European cohort study (ESCAPE) its association with cancer mortality was investigated on the basis of individual effective dose estimates for 19,184 male pilots. Mean annual doses were in the range of 2-5 mSv and cumulative lifetime doses did not exceed 80 mSv. All-cause and all-cancer mortality was low for all exposure categories. A significant negative risk trend for all-cause mortality was seen with increasing dose. Neither external and internal comparisons nor nested case-control analyses showed any substantially increased risks for cancer mortality due to ionizing radiation. However, the number of deaths for specific types of cancer was low and the confidence intervals of the risk estimates were rather wide. Difficulties in interpreting mortality risk estimates for time-dependent exposures are discussed.

Breast cancer risk in airline cabin attendants: a nested case-control study in Iceland.

AIMS: To investigate whether length of employment as a cabin attendant was related to breast cancer risk, when adjusted for reproductive factors. METHODS: Age matched case-control study nested in a cohort of cabin attendants. The cases were found from a nationwide cancer registry (followed up to end of year 2000) and the reproductive factors (age at first childbirth and number of children) from a registry of childbirth, in both instances by record linkage with the cabin attendants' identification numbers. The employment time of the cabin attendants at the airline companies and the reproductive factors had been systematically recorded prior to the diagnosis of breast cancer in the cohort. A total of 35 breast cancer cases and 140 age matched controls selected from a cohort of 1532 female cabin attendants were included in the study. RESULTS: The matched odds ratio from conditional logistic regression of breast cancer risk among cases and controls of cabin attendants was 5.24 (95% CI 1.58 to 17.38) for those who had five or more years of employment before 1971 compared with those with less than five years of employment before 1971, adjusted for age at first childbirth and length of employment from 1971 or later. CONCLUSIONS: The association between length of employment and risk of breast cancer, adjusted for reproductive factors, indicates that occupational factors may be an important cause of breast cancer among cabin attendants; the association is compatible with a long induction period.

Risk factors for cutaneous malignant melanoma among aircrews and a random sample of the population.

AIMS: To evaluate whether a difference in the prevalence of risk factors for malignant melanoma in a random sample of the population and among pilots and cabin attendants could explain the increased incidence of malignant melanoma which had been found in previous studies of aircrews. METHODS: A questionnaire was used to collect information on hair colour, eye colour, freckles, number of naevi, family history of skin cancer and naevi, skin type, history of sunburn, sunbed, all sunscreen use, and number of sunny vacations. RESULTS: The 239 pilots were all males and there were 856 female cabin attendants, which were compared with 454 males and 1464 females of the same age drawn randomly from the general population. The difference in constitutional and behavioural risk factors for malignant melanoma between the aircrews and the population sample was not substantial. The aircrews had more often used sunscreen and had taken more sunny vacations than the other men and women. The predictive values for use of sunscreen were 0.88 for pilots and 0.85 for cabin attendants and the predictive values for sunny vacation were 1.36 and 1.34 respectively. CONCLUSION: There was no substantial difference between the aircrew and the random sample of the population with respect to prevalence of risk factors for malignant melanoma. Thus it is unlikely that the increased incidence of malignant melanoma found in previous studies of pilots and cabin attendants can be solely explained by excessive sun exposure.

Overview of atmospheric ionizing radiation (AIR) research: SST-present.

The Supersonic Transport (SST) program, proposed in 1961, first raised concern for the exposure of pregnant occupants by solar energetic particles (SEP), and neutrons were suspected to have a main role in particle propagation deep into the atmosphere. An eight-year flight program confirmed the role of SEP as a significant hazard and of the neutrons as contributing over half of the galactic cosmic ray exposures, with the largest contribution from neutrons above 10 MeV. The FAA Advisory Committee on the Radiobiological Aspects of the SST provided operational requirements. The more recent lowering of ICRP-recommended exposure limits (1990) with the classification of aircrew as "radiation workers" renewed interest in GCR background exposures at commercial flight altitudes and stimulated epidemiological studies in Europe, Japan, Canada and the USA. The proposed development of a High Speed Civil Transport (HSCT) required validation of the role of high-energy neutrons, and this resulted in ER-2 flights at solar minimum (June 1997) and studies on effects of aircraft materials on interior exposures. Recent evaluation of health outcomes of DOE nuclear workers resulted in legislation for health compensation in year 2000 and recent European aircrew epidemiological studies of health outcomes bring renewed interest in aircraft radiation exposures. As improved radiation models become available, it is imperative that a corresponding epidemiological program of US aircrew be implemented.

Cause-specific mortality in adults with unprovoked seizures. A population-based incidence cohort study.

PURPOSE: To determine the cause-specific mortality relative to that expected in a population-based incidence cohort of people with unprovoked seizures. METHODS: The cohort comprises 224 inhabitants of Iceland first diagnosed as suffering from unprovoked seizures during a 5-year period from 1960 to 1964. The expected number of deaths was calculated by multiplying person-years of observation within 5-year age categories for each year from diagnosis through 1995 by cause-specific and sex-specific national death rates for those aged 20 years and above. The standardized mortality ratio (SMR) and 95% confidence intervals (95% CI) were calculated. RESULTS: All-cause mortality was increased among men (SMR 2.25, 95% CI 1.56-3.14) but not women (SMR 0.79, 95% CI 0.38-1.46). Among men, there were 8 deaths from accidents, poisoning and violence observed versus 2.82 expected (SMR 2.84, 95% CI 1.22-5.59) and 4 deaths from suicide versus 0.69 expected (SMR 5.80, 95% CI 1.56-14.84). All-cause mortality for men was still elevated after restriction of analysis to those with seizures of unknown etiology (SMR 1.73, 95% CI 1.05-2.67) with the excess deaths attributable to suicide (SMR 5.26, 95% CI 1.06-15.38). Both males and females with remote symptomatic unprovoked seizures had an increase in all-cause mortality due to excess mortality from all cancers, cerebrovascular disease and accidents. CONCLUSION: When compared with the age-, time-period- and gender-specific mortality in the general population, there is excess mortality in men but not women. The increased mortality for men is partly attributable to excess mortality from accidents and suicides.

Incidence of cancer among bookbinders, printers, photoengravers, and typesetters.

OBJECTIVES: To to study the risk of cancer, particularly of lung cancer and bladder cancer, among workers in the printing industry according to different occupations. METHODS: This is a population based retrospective cohort study. The cohort comprised 1332 men and 426 women employed in the printing industry in Iceland according to a published union registry. A computerised file of the cohort was record linked to the Cancer Registry by making use of personal identification numbers. Expected numbers of cases of cancer were calculated on the basis of number of person-years and specific incidences of cancer sites for men and women provided by the Cancer Registry. RESULTS: Among the men (36 217.5 person-years at risk) there were 125 observed cancers versus 123.66 expected, standardised incidence ratio (SIR) 1.01, 95% confidence interval (95% CI) was 0.84 to 1.20. The SIR (95% CI) for liver cancer was 1.97 (0.55 to 5.20) and the SIR for non-Hodgkin's lymphoma was 2.26 (0.96 to 4.41). No excess risk for cancer was found among women (8631.0 person-years at risk). The SIR (95% CI) for liver cancer was 4.21 (0.47 to 15.20) and for non-Hodgkin's lymphoma it was 4.99 (1.61 to 11.63) among the typesetters. A survey on smoking habits among active and retired union members showed that they smoked less than a random sample of the general population. CONCLUSION: The cancer site most often reported to show excess risk among printing industry workers has been the lung and the urinary bladder; however, this was not found in the present study. This may be explained by difference in smoking habits among union members compared with the general population. There is a high occurrence of non-Hodgkin's lymphoma, particularly among typesetters, which warrants further studies.

Risk of breast cancer in female flight attendants: a population-based study (Iceland).

OBJECTIVES: To study whether increased cancer risk, particularly of cancer types previously related to radiation, was found among cabin attendants, using employment time as a surrogate of exposure to cosmic radiation. METHODS: A cohort of 1690 cabin attendants, 158 men and 1532 women from the Icelandic Cabin Crew Association and two airline companies in Iceland, was established. Cancer sites were ascertained between 1955 and 1997 by follow-up in a cancer registry. The personal identification number of each subject was used in record linkage to population-based registers containing vital and emigration status, reproductive factors and histologically verified cancer diagnosis. Standardized incidence rates (SIR) of different cancer sites in relation to employment time and year of hiring were calculated, as well as predictive values of breast cancer risk for evaluating possible confounding due to reproductive factors. RESULTS: The total number of person-years was 27,148. Among the women, 64 cancers were observed whereas 51.63 were expected (SIR 1.2, 95% CI 1.0-1.6), and significantly increased risk for malignant melanoma (SIR 3.0, 95% CI 1.2-6.2) was found. Significantly increased risks of overall cancers (SIR 1.3, 95% CI 1.0-1.8) and breast cancer (SIR 1.6, 95% CI 1.0-2.4) were observed among the female cabin attendants when 15 years lag time was applied. Those hired in 1971 or later had the heaviest exposure to cosmic radiation at a young age and had significantly increased risk of overall cancer (SIR 2.8, 95% CI 1.4-4.9) and breast cancer (SIR 4.1, 95% CI 1.7-8.5). Predictive values calculated on the basis of reproductive factors among the cabin attendants and the population, and risk of breast cancer were 1.0 for parous vs. nulliparous, 1.0 for number of children, and 1.1 for age at birth of first child. CONCLUSION: The increased risk of breast cancer and malignant melanoma among cabin attendants seems to be occupationally related. The part played by occupational exposures, i.e. cosmic radiation, disturbance of the circadian rhythm, and electromagnetic fields or combination of these factors in the etiology of breast cancer among the cabin crew, is still a puzzle as confounding due to parity appears to be ruled out. The relationship between the sunbathing habits of the cabin crew and the increased risk of malignant melanoma needs to be clarified. There is also an urgent need to elucidate the importance of these findings for today's aviation.

[Changes in the prevalence of disability pension in Iceland 1976-1996.].

OBJECTIVE: To determine changes in the prevalence of disability pension in Iceland and to describe the distribution of those receiving disability pension according to gender, age and main diagnoses between the years 1976 and 1996. MATERIAL AND METHODS: The study includes all those receiving disability pension on the 1st of December in the years 1976 and 1996 as ascertained by the disability register at the State Social Security Institute of Iceland. There are two levels of disability pension, full disability pension (disability assessed as being more than 75%) and reduced disability pension (disability assessed as being 50% or 65%). Information on age and gender distribution of the Icelandic population was obtained. Age-standardized risk ratio between the years 1976 and 1996 was calculated for both pension levels combined and for full disability pension alone. RESULTS: There was no significant change in crude prevalence rate for both pension levels combined between the years 1976 and 1996, when the increase in the population was accounted for but without paying attention to changes in gender or age distribution. However, the standardized risk ratio showed a significantly decreased risk for both pension levels combined both for men and women in the year 1996 as compared with the year 1976, the age-standardized risk ratio being 0.95 and 0.93 respectively. It also showed a significant change between pension levels with an increased risk of full disability pension and a decreased risk of reduced disability pension. The increase in full disability pension was noted for both males and females and was largely independent of age. There was a significant increase in full disability pension in most disease categories. Disability due to diseases of the nervous system and sense organs and injury and poisoning increased amongst women only. A significant decrease in full disability pension due to infections and diseases of the digestive system occurred in both men and women. CONCLUSION: The prevalence of a disability pension amongst men and women in the year 1996 as compared to the year 1976 was significantly decreased when changes in population size and age distribution had been accounted for. This is particularly interesting because unemployment was increasing just prior to the year 1996. The prevalence of full disability pension had however significantly increased in 1996 compared with 1976. A plausible explanation for the observed change in disability pension levels is a pressure from the labour market, with increasing unemployment and competition. Also, the introduction of a disability card for those with full disability pension in 1980, which granted lower price for medication and the services of physicians, is likely to have increased the pressure for the higher level of disability pension (full disability pension). It seems unlikely that the increase in full disability pension and the decrease in reduced disability pension is due to a deterioration of health of the Icelandic population. Increased disability due to injury and poisoning amongst women is probably a result of their increased participation in the labour market. The decrease in disability due to infections is a result of a reduction in the number of cases of tuberculosis and poliomyelitis. The decrease in disability due to diseases of the digestive system is probably a result of improvement in the treatment of oesophageal reflux and peptic ulcer.

Incidence of cancer among commercial airline pilots.

OBJECTIVES: To describe the cancer pattern in a cohort of commercial pilots by follow up through the Icelandic Cancer Registry. METHODS: This is a retrospective cohort study of 458 pilots with emphasis on subcohort working for an airline operating on international routes. A computerised file of the cohort was record linked to the Cancer Registry by making use of personal identification numbers. Expected numbers of cancer cases were calculated on the basis of number of person-years and incidences of cancer at specific sites for men provided by the Cancer Registry. Numbers of separate analyses were made according to different exposure variables. RESULTS: The standardised incidence ratio (SIR) for all cancers was 0.97 (95% confidence interval (95% CI) 0.62 to 1.46) in the total cohort and 1.16 (95% CI 0.70 to 1.81) among those operating on international routes. The SIR for malignant melanoma of the skin was 10.20, 95% CI 3.29 to 23.81 in the total cohort and 15.63, 95% CI 5.04 to 36.46 in the restricted cohort. Analyses according to number of block-hours and radiation dose showed that malignant melanomas were found in the subgroups with highest exposure estimates, the SIRs were 13.04 and 28.57 respectively. The SIR was 25.00 for malignant melanoma among those who had been flying over five time zones. CONCLUSIONS: The study shows a high occurrence of malignant melanoma among pilots. It is open to discussion what role exposure of cosmic radiation, numbers of block-hours flown, or lifestyle factors--such as possible excessive sunbathing--play in the aetiology of cancer among pilots. This calls for further and more powerful studies. The excess of malignant melanoma among those flying over five time zones suggests that the importance of disturbance of the circadian rhythm should be taken into consideration in future studies.

Musculoskeletal symptoms among women currently and formerly working in fish-filleting plants.

The authors surveyed women currently or formerly working in fish-filleting plants to evaluate their musculoskeletal symptoms, using the standardized Nordic Questionnaire on musculoskeletal symptoms. The women's work consisted of cutting and trimming fish fillets, which were transported to and from the work stations by conveyor belts. The prevalence of musculoskeletal symptoms during the preceding 12 months was higher among former than current workers. The Mantel-Haenszel odds ratio for symptoms of the fingers, ankles, and wrists hindering normal work during the preceding 12 months were 7.1 (95% CI 2.8-18.0), 5.3 (95% CI 1.3-21.5(, and 3.4 (95% CI 1. 3-8.8), respectively. The higher prevalence of musculoskeletal symptoms among those who had stopped working at the fish-filleting plants than among those continuing to do so indicates a healthy-worker selection. There may be a causal relationship between musculoskeletal symptoms and ceasing to work at the plants.

Cytogenetics of myelodysplasia and acute myeloid leukaemia in aircrew and people treated with radiotherapy.

Increased risk of acute myeloid leukaemia has been reported in aircrew, possibly in association with cosmic radiation. We studied the cytogenetics of seven aircrew members who had acute myeloid leukaemia or myelodysplasia and found deletion or loss of chromosome 7 in four. The same abnormality was found in eight of 19 patients with leukaemia after radiotherapy alone. By comparison, only 81 of 761 unselected cases of myelodysplasia or acute myeloid leukaemia had the same cytogenetic abnormalities. Our results support the concept that deletions or loss of the long arm of chromosome 7 in myelodysplasia and acute myeloid leukaemia could indicate previous exposure to ionising radiation.

[Cancer Incidence among Female Manual Workers.].

We investigated cancer incidence during the period 1970-1992 among unskilled Icelandic female workers who contributed to two pension funds for manual workers. We found an increase in the standardized rate ratios (SRRs) for all cancer with increasing time before the follow-up period began. We found no clear relation between cancer incidence and length of employment. The SRRs were higher for those who became members of the funds in 1977 or later than for those who started earlier: among these women we found SRRs for all cancers, 1.36; cancer of the stomach, 1.49; cancer of the lung, 1.48; cancer of the cervix, 3.19; and cancer of the bladder, 6.00.

[Increase in musculo-skeletal symptoms of upper limbs among women after the introduction of the flow-line in the fish-fillet plants.].

OBJECTIVES: An earlier study of workers in fish-fillet plants in Iceland showed higher prevalence of musculoskeletal symptoms as compared to a random sample of the Icelandic population. Since that study a new manufacturing process, the flow-line, has been introduced. The aim of this study was to evaluate whether this new work situation changed the prevalence of musculoskeletal symptoms among the workers of the fish-fillet plants. MATERIAL AND METHODS: The same standardised Nordic Questionnaire was used in both surveys. RESULTS: The monotony and the repetitiveness of the work increased with the new technique. The results showed that women had higher prevalence of symptoms of the upper limbs when working at the flow-line than before. The Mantel-Haenszel odds ratio for symptoms of elbows, fingers and wrists during the last seven days prior to the study was 2.1 (95% confidence interval (CI) 1.0-4.4), 1.9 (95% CI 1.1-3.2) and 1.7 (95% CI 1.0-2.7). The odds ratio for knees and ankles was less than one. CONCLUSIONS: The higher prevalence of symptoms of the upper limbs seems to be causally related to the increase of monotonous and repetitive work in the fish industry.