Exposure to carbon disulphide and ischaemic heart disease in a viscose rayon factory

The cohort of viscose rayon workers previously described by Tiller et al has been reconstructed and followed up to the end of 1982. The pattern of mortality at ages 45 to 64 for the extended period 1950-82 is similar to that described by Tiller et al for 1950-64. The spinners, the workers most heavily exposed to carbon disulphide, have a significantly higher mortality from all causes than the least exposed group. The excess mortality is largely accounted for by ischaemic heart disease (IHD) for which the spinners have an SMR of 172. When mortality is related to an exposure score in the same group, both all cause (p less than 0.01) and IHD (p less than 0.001) mortality increase with increasing exposure level. When this analysis is repeated covering all ages these trends become much less strong and only that for IHD remains significant (p less than 0.05). Over the age of 65 there is a tendency for mortality to decline with increasing exposure. This is contrary to expectation under the usual hypothesis that carbon disulphide promotes atherosclerosis. Instead it suggests that carbon disulphide has some type of reversible, direct cardiotoxic or thrombotic effect. This is supported by the findings that there is a strong trend (p less than 0.01) for IHD mortality to increase with increasing exposure in the previous two years. Further, both IHD (p less than 0.001) and total (p less than 0.01) mortality show highly significant trends with exposure among current workers but no such trends among workers who have left the industry.     

Mortality and disability among cotton mill workers

The mortality and disability of cotton mill workers were studied in five Finnish cotton mills. The population under study comprised all 1065 women exposed to raw cotton dust who had been hired between 1950 and 1971. The minimum exposure period was five years. For the study on disability, the cohort was followed up until the end of 1981. The follow up period for the mortality analysis was from 1950 to 1985. At the end of 1981 the observed number of prevalent disability pensions for respiratory disease was 15, whereas 3.9 were expected (p less than 0.01) on the basis of the national figures for women. There were 46 musculoskeletal diseases (27.7 expected, p less than 0.01), of which 24 were osteoarthritis (14.5 expected) and 13 rheumatoid arthritis (6.6 expected). The incidence rates of disability pensions were calculated for the period 1969-81. Comparison of incidence rates between cotton mill workers and the Finnish female population showed excessive rates for both respiratory diseases (p less than 0.001) and musculoskeletal diseases (p less than 0.01), with an excess of new cases of rheumatoid arthritis (p less than 0.05). By the end of 1985 the number of person-years was 31,678 and the number of deaths 95. The standardised mortality ratios for the total period of follow up (1950-85) showed no excess for respiratory diseases. Mortality from cardiovascular diseases was also lower than expected. The observed number of tumours was 33, the corresponding expected number 32.0. Thirteen tumours were in the digestive organs (6.6 expected, p<0.05) and three were lung cancers (1.9 expected). Five workers had died from renal disease; the expected number was 1.5 (p<0.05).     

Mortality and disability among cotton mill workers.

The mortality and disability of cotton mill workers were studied in five Finnish cotton mills. The population under study comprised all 1065 women exposed to raw cotton dust who had been hired between 1950 and 1971. The minimum exposure period was five years. For the study on disability, the cohort was followed up until the end of 1981. The follow up period for the mortality analysis was from 1950 to 1985. At the end of 1981 the observed number of prevalent disability pensions for respiratory disease was 15, whereas 3.9 were expected (p less than 0.01) on the basis of the national figures for women. There were 46 musculoskeletal diseases (27.7 expected, p less than 0.01), of which 24 were osteoarthritis (14.5 expected) and 13 rheumatoid arthritis (6.6 expected). The incidence rates of disability pensions were calculated for the period 1969-81. Comparison of incidence rates between cotton mill workers and the Finnish female population showed excessive rates for both respiratory diseases (p less than 0.001) and musculoskeletal diseases (p less than 0.01), with an excess of new cases of rheumatoid arthritis (p less than 0.05). By the end of 1985 the number of person-years was 31,678 and the number of deaths 95. The standardised mortality ratios for the total period of follow up (1950-85) showed no excess for respiratory diseases. Mortality from cardiovascular diseases was also lower than expected. The observed number of tumours was 33, the corresponding expected number 32.0. Thirteen tumours were in the digestive organs (6.6 expected, p<0.05) and three were lung cancers (1.9 expected). Five workers had died from renal disease; the expected number was 1.5 (p<0.05).     

Ischemic heart disease mortality among heavy equipment operators

BACKGROUND: Inhalation of fine particulate is hypothesized to increase risk of heart disease events. METHODS: Seven Ontario construction unions participated in a retrospective cohort mortality study. Proportional mortality ratios (PMRs) were computed and a mortality odds ratio (MOR) analysis was performed to compare the risk of ischemic heart disease (IHD) mortality among heavy equipment operators (HEO) to that of members of other unions. Deaths attributed to lung cancer, mesothelioma, and accidental causes were excluded from the comparison. RESULTS: Two hundred fifty nine of 1,009 deaths among the HEO were attributed to IHD. The PMR was 1.09 (0.96-1.2). None of the IHD PMRs among the other six unions exceeded 0.89. The MOR for IHD mortality, comparing the HEO to all other workers combined was 1.47 (1.17-1.84) for ages 25-64, was 1.20 (0.96-1.50) for ages 65 or more, and was 1.32 (1.13-1.55) for all ages combined. CONCLUSIONS: Increased risk of IHD mortality among HEO is consistent with the hypothesis that exposure to diesel fume has adverse effects upon the heart and circulatory system.     

Mortality from heart disease among workers exposed to solvents

Several rubber industry jobs that are associated with cardiovascular disease (CVD) mortality involve the use of solvents and, since the only known occupational cause of atherosclerosis is a solvent (carbon disulfide), solvent exposures may contribute to the CVD excess observed among rubber industry workers. Detailed exposure estimates for 25 solvents were available for a cohort of 1,282 white male production workers in a large rubber- and tire-manufacturing plant, and a survivorship analysis compared the CVD mortality experience of exposed and nonexposed workers during a 15-year follow-up period. The known association between carbon disulfide exposure and ischemic heart disease (IHD) was apparent among these workers, and two other solvents, ethanol and phenol, were also found to be significant predictors of IHD. These exploratory findings suggest that solvents other than carbon disulfide may cause atherosclerotic disease.     

Long-term effect of occupational dust exposure

In 1950-1960, a cohort of dust-exposed workers and a cohort of multiple matched unexposed subjects was set up from the files of preventive medical checkups performed in 1,089 Viennese plants. Male workers with a history of long-term exposure to nonfibrous particulates in different industries (metal, ceramics, brick, glass, stone etc.) aged greater than or equal to 40, and male workers without dust exposure (matched for residency, start of observation, age, and smoking) were followed up to 1980 or death (48,960 person yr). By life table methods, dust-exposed workers compared to unexposed workers showed a reduced survival of age 60 (p less than 0.0001), due to lung cancer (123 exposed, 87 controls, p = 0.001), stomach cancer (48/27, p = 0.003), silicosis (40/0), emphysema, bronchitis and asthma (41/23, p = 0.007). No difference in mortality from cardiovascular diseases was observed (p greater than 0.50). We concluded that heavy and long term exposure to respirable particulates is related to increased lung cancer mortality after age 60. A comparison of 2,212 deaths among Austrian silicotics, with deaths in the corresponding population showed a relation between lung cancer and silicosis (p less than 0.001), fairly independent of age and time-period. The estimated relative lung cancer risk of Austrian silicotics in the period 1955-79 averaged 1.41 (95% confidence 1.21-1.64).     

A follow-up study of coronary heart disease in viscose rayon workers exposed to carbon disulphide.

In 1967 two cohorts of 343 men each were formed and matched with respect to age, district of birth, and similarity of work. One cohort comprised viscose rayon workers with at least five years' exposure to carbon disulphide during any period between 1942 and 1967, and the other cohort consisted of workers from a paper-mill with no such exposure. The concentrations of carbon disulphide and hydrogen sulphide in the workroom air had been measured regularly since 1950, and about 4000 measurements were available. In all probability the concentrations had been very high in the 1940s, between 20 and 40 ppm in the 1950s, and about 10 to 30 ppm from 1960 onwards. On examination in 1967 it was confirmed that all of the relevant coronary risk factors had been kept under control. The only exception to this was blood pressure which was slightly higher among the exposed workers, a finding that was interpreted as a result of exposure rather than an independent risk factor. A five-year follow-up showed that 14 men had died from coronary heart disease (CHD) in the exposed group, against three in the control group (P smaller than 0:007). Other causes of death were evenly distributed. In addition, 11 nonfatal first infarctions had occurred in the exposed group as compared with four in the control group. On re-examination in 1972, nearly 25% of the exposed men, against 13% of the controls, had a history of angina (typical, probable, and possible) as measured by the World Health Organization questionnaire (P smaller than 0:0002). The prevalence proportions of typical angina were 12% and 5% respectively (P smaller than 0:001). As opposed to this, only slight differences were apparent for coronary ECGs. The higher degrees of prevalance in the exposed group may well have been attributable to chance. As in 1967/68, the mean systolic and diastolic blood pressures were slightly higher in the exposed group (P smaller than 0:001 and P smaller than 0:01, respectively). The relative risk was 4-8 for fatal attacks, 3-7 for all infarctions, 2-8 for nonfatal infarctions, 2-2 for angina, and 1-4 for ECG findings indicative of CHD. This implies that with increasing severity and specificity of the manifestations the causal role of CS2 in developing CHD becomes more evident. Further, it is inferred that exposure to CS2 seems to worsen the prognosis of CHD in addition to increasing its incidence. Although the exposure data in this study may not be representative of the personal exposure of the workers, the conclusion is drawn that a great deal of justification exists for lowering the threshold limit value of 20 ppm recommended by the American Conference of Governmental Industrial Hygienists.     

Ischemic heart disease in nuclear workers first employed at the Mayak PA in 1948-1972

Following an earlier study of incidence and mortality of ischemic heart disease (IHD) published in 2010, a second analysis has been conducted based on an extended cohort and five additional years of follow-up. The cohort includes 18,763 workers, of whom 25% were females, first employed at the Mayak PA in 1948-1972 and followed up to the end of 2005. Some of these workers were exposed to external gamma rays only, and others were exposed to a mixture of external gamma-rays and internal alpha-particle radiation. A total of 6,134 cases and 2,629 deaths from IHD were identified in the study cohort. A statistically significant increasing trend was found with total external gamma-ray dose in IHD incidence (ERR/Gy 0.099; 95% CI: 0.045-0.153) after adjusting for non-radiation factors. This value reduced slightly when adjusting for internal liver dose. There was no statistically significant increase trend for internal liver dose in IHD incidence. These findings were consistent with an earlier study. New findings in IHD incidence revealed a statistically significant decrease in IHD incidence among workers exposed to external gamma-rays doses of 0.2-0.5 Gy in relation to the external doses below 0.2 Gy. This decreased risk is heavily influenced by female workers. This finding has never been reported in other studies, and the results should be treated with caution. The findings for IHD mortality are similar to those results in the earlier analysis; there was no statistically significant trend with external gamma-ray dose or for internal liver dose after adjustment for external dose. The risk estimates obtained from these analyses of IHD incidence and mortality in relation to external gamma-rays in the cohort of Mayak workers are generally compatible with those from other large occupational radiation worker studies and the Japanese atomic bomb survivors.     

Changing patterns of ischaemic heart disease mortality in New Jersey 1968-1982, and the relationship with urbanization

Geographical variations in the declining rates of ischaemic heart disease (IHD) mortality may provide clues about various environmental risk factors responsible as a mass influence on the population IHD rate. The rate of IHD decline in 18 of 21 NJ counties was 2 to 45% less than the USA national rate of decline. The overall decline of IHD mortality in New Jersey (NJ) counties lagged significantly (p less than 0.05 to p less than 0.0003) behind the national trend. Age-adjusted mortality rate (AAMR) for IHD in NJ's 21 counties were 4% to 56% higher than the US rates. The IHD mortality rate of 14 of 21 NJ, counties and the entire state were significantly (p less than 0.005 to p less than 0.000001) above the US rate. Highly urbanized, industrialized, and densely populated NJ counties had the highest IHD rates. In these highly urbanized, industrialized and overcrowded NJ counties the AAMR for IHD was significantly higher and the IHD decline was significantly lower than that in the US. There was a significant (p less than 0.02 to p less than 0.00001) inverse association between annual per capita income and IHD rates. These data suggest that a high degree of urbanization, extensive industrialization, high population density and low socioeconomic status were acting as mass influences on the NJ population IHD rate.     

Serum type III procollagen peptide in asbestos workers: an early indicator of pulmonary fibrosis

Serum type III procollagen peptide (PIIIP) concentrations were determined in 36 male workers exposed to asbestos fibres in the production of asbestos cement items and in 13 healthy male controls. Mean (SD) PIIIP serum concentrations were 9.3 (1.5) ng/ml (range 7-12) in the controls and 13.7 (3.5)ng/ml (range 7.5-20) in the asbestos workers; the difference was statistically significant (p less than 0.01). The exposed workers were subdivided according to presence or absence of radiological signs of asbestosis and intensity and duration of exposure. PIIIP serum values of workers with asbestos related interstitial fibrosis were the highest of the groups at 14.6 (2.3) ng/ml. In workers with heavy exposure the PIIIP values were significantly related to duration of exposure (r = 0.95; p less than 0.01). PIIIP serum values may be a useful index for the early diagnosis of asbestos induced pulmonary fibrosis and its use should be considered as part of the biological monitoring of exposed workers.     

Serum type III procollagen peptide in asbestos workers: an early indicator of pulmonary fibrosis.

Serum type III procollagen peptide (PIIIP) concentrations were determined in 36 male workers exposed to asbestos fibres in the production of asbestos cement items and in 13 healthy male controls. Mean (SD) PIIIP serum concentrations were 9.3 (1.5) ng/ml (range 7-12) in the controls and 13.7 (3.5)ng/ml (range 7.5-20) in the asbestos workers; the difference was statistically significant (p less than 0.01). The exposed workers were subdivided according to presence or absence of radiological signs of asbestosis and intensity and duration of exposure. PIIIP serum values of workers with asbestos related interstitial fibrosis were the highest of the groups at 14.6 (2.3) ng/ml. In workers with heavy exposure the PIIIP values were significantly related to duration of exposure (r = 0.95; p less than 0.01). PIIIP serum values may be a useful index for the early diagnosis of asbestos induced pulmonary fibrosis and its use should be considered as part of the biological monitoring of exposed workers.     

A cytogenetic and haematological investigation of oil exposed workers in a Norwegian cable manufacturing company.

Cytogenetic and haematological parameters were studied in 31 oil exposed workers and 31 office workers matched for age and smoking, all men employed by a Norwegian cable manufacturing company. Information was obtained about tobacco and alcohol consumption, infections, allergies, chronic diseases, use of medicines, and exposure to radiography. A decrease in the absolute lymphocyte counts was observed in the most heavily exposed subgroup (p less than 0.05) but no other significant differences were found between exposed workers and referents. The influence of non-occupational variables on the cytogenetic parameters was studied by stepwise multiple linear regression analysis. The frequency of sister chromatid exchanges appeared to be influenced by smoking history (p less than 0.05) and season of sampling (p less than 0.01) and, if season was excluded, by age (p less than 0.05) and current smoking (p less than 0.05). The number of cells with chromosomal aberrations increased with age (p less than 0.05) and lymphocyte count (p less than 0.05), whereas the frequency of stable rearrangements was negatively correlated with current smoking (p less than 0.01).     

Cardiovascular effects of occupational exposure to carbon disulphide

The objective of this study was to investigate the effect of occupational exposure to carbon disulphide (CS2) on the total cholesterol, blood pressure and prevalence of coronary heart disease (CHD). A cross-sectional study involving 252 viscose rayon workers and 252 age and sex matched controls was carried out. Depending on the job and specific work place, the CS2 concentrations were between 10 and 64 mg/m3. A cumulative exposure index (CS2 index) was calculated for each worker by multiplying the number of years he had held a particular job with the CS2 concentrations in that job. CHD prevalence among the exposed was higher than among the controls; the difference reaching significance only for highly exposed workers. Cholesterol levels were significantly higher in both highly and moderately exposed groups. In conclusion, the results demonstrated that occupational exposure to CS2 increases total cholesterol and the risk for CHD. While the risk for CHD is increased in workers exposed to high CS2 concentration for many years (CS2 index > or = 300), even the relatively modest exposure (CS2 < 300) may increase the serum cholesterol.     

Ischemic heart disease mortality among miners and other potentially silica-exposed workers

BACKGROUND: Some previous studies have observed an increased mortality regarding ischemic heart disease (IHD) among miners and industrial sand workers. The purpose was to study the occurrence of IHD mortality among silica-exposed workers. METHODS: Male miners, well borers, dressing plant workers, and other mine and stone workers were identified in the Swedish National Census of 1970. The total cohort (n = 11,896) was followed from 1970 until December 31, 1995 and linked to the Cause of Death Register. The referent group comprised all gainfully employed men identified in the same census. The Standardized Mortality Ratio was calculated as the ratio between observed and expected numbers of deaths. RESULT: An increased risk due to IHD mortality was observed among miners, well borers, dressing plant workers, and other mine and stone workers. CONCLUSION: These results indicate a possible relation between silica-dust exposure and IHD. The increased risk of IHD mortality is unlikely explained by smoking habits. Shift work might explain some of the increased risk. A low-grade inflammation in the lungs as a result of dust exposure is discussed as a possible cause. However, the key message is that better dose estimates and better confounding control is needed to study the possible relation between silica-dust exposure and IHD.     

A cytogenetic and haematological investigation of oil exposed workers in a Norwegian cable manufacturing company

Cytogenetic and haematological parameters were studied in 31 oil exposed workers and 31 office workers matched for age and smoking, all men employed by a Norwegian cable manufacturing company. Information was obtained about tobacco and alcohol consumption, infections, allergies, chronic diseases, use of medicines, and exposure to radiography. A decrease in the absolute lymphocyte counts was observed in the most heavily exposed subgroup (p less than 0.05) but no other significant differences were found between exposed workers and referents. The influence of non-occupational variables on the cytogenetic parameters was studied by stepwise multiple linear regression analysis. The frequency of sister chromatid exchanges appeared to be influenced by smoking history (p less than 0.05) and season of sampling (p less than 0.01) and, if season was excluded, by age (p less than 0.05) and current smoking (p less than 0.05). The number of cells with chromosomal aberrations increased with age (p less than 0.05) and lymphocyte count (p less than 0.05), whereas the frequency of stable rearrangements was negatively correlated with current smoking (p less than 0.01).     

二硫化碳作业男工性功能和精液状态的调查研究

对接触CS_2的平均浓度为35mg/m~3的18名已婚纺丝男工性功能调查结果,性欲减退者36.8%,显著高于对照组.对100名纺丝男工精液检查结果,精子形态异常率高者、精子活动率低者、精子数少者和精液液化时间长者分别有64%、48%、37%和17%,均显著高于对照组.表明CS_2能损害男工性功能和精液生成.     

二硫化碳作业男工性功能和精液状态的调查研究

对接触CS_2的平均浓度为35mg/m3的38名已婚纺丝男工性功能调查结果,性欲减退者36.8％,显著高于对照组。对100名纺丝男工精液检查结果,精子形态异常率高者、精子活动率低者、精子数少者和精液液化时间长者分别有64％、48％、37％和17％,均显著高于对照组。表明CS_2能损害男工性功能和精液生成。     

Mortality of a cohort of tin miners 1941-86.

The mortality patterns of United Kingdom tin miners were examined in relation to calendar period and duration of underground work with particular attention to lung cancer and exposure to radon. Subjects were all men who had worked for at least one year between 1941 and 1984 at one of two United Kingdom tin mines and for whom a complete work history could be constructed from mine records. Standardised mortality ratios (SMRs) were calculated using national (England and Wales) rates. The pattern of SMRs in relation to potential explanatory variables was analysed using Poisson regression methods. Mortalities from lung cancer and silicosis (including silicotuberculosis) were significantly raised and showed a significant relation with duration of underground work (mortality from stomach cancer was raised in both underground and surface workers, but not significantly). Excess mortality from silica related disease declined steeply from 35% among workers first exposed before 1920 to 1% among those first exposed after 1950. Thirteen surface workers with known exposure to arsenic had high rates of lung and stomach cancer. The SMR for lung cancer showed a consistent pattern in relation to duration of underground exposure, rising from 83 (observed/expected = 8/9.6) for surface workers (without exposure to arsenic) to 447 (15/3.4) for workers with more than 30 years underground exposure. Examination of the SMR for lung cancer by total underground exposure, age, and time since last exposure gave rise to a model for the expression of risk which depends only on total exposure and time since exposure. The fitted model implies that the effect of exposure to radon in a given year has no effect on risk for 10 years, then rapidly rises to a maximum from which the excess risk then declines, halving every 4.3 years. There were no direct measurements of historic radon levels. A conservative estimate based on measurements taken since 1969 by the National Radiological Protection Board and the Mines and Quarries Inspectorate is that the annual dose to an underground worker was about 10 working level months (WLM). Given this assumption, the risk/exposure slope implied by the present data, and the model fitted to it, was somewhat lower than that given in the fourth Committee on the Biological Effects of Ionisation Radiation (BEIR IV) report (about 40% lower for lifetime exposures). The present data also imply different risks depending on the age at exposure, with relatively higher lifetime risks for exposure at older ages, and relatively lower risks for exposures at younger ages. In conclusion, there was a clear relation between exposure to radon and death from lung cancer. The relative risk of lung cancer due to exposure to radon was not constant in cessation of exposure. The lifetime excess risk of lung cancer implied by these data for 40 years exposure at the current statutory limit of four WLM a year starting at age 20, was about 8% (79 excess deaths per 1000 exposed), assuming average smoking habits among the exposed workers. Control of dust concentrations in the mines has substantially reduced--and may have eliminated--direct mortality from silica related disease.     

Mortality of a cohort of tin miners 1941-86

The mortality patterns of United Kingdom tin miners were examined in relation to calendar period and duration of underground work with particular attention to lung cancer and exposure to radon. Subjects were all men who had worked for at least one year between 1941 and 1984 at one of two United Kingdom tin mines and for whom a complete work history could be constructed from mine records. Standardised mortality ratios (SMRs) were calculated using national (England and Wales) rates. The pattern of SMRs in relation to potential explanatory variables was analysed using Poisson regression methods. Mortalities from lung cancer and silicosis (including silicotuberculosis) were significantly raised and showed a significant relation with duration of underground work (mortality from stomach cancer was raised in both underground and surface workers, but not significantly). Excess mortality from silica related disease declined steeply from 35% among workers first exposed before 1920 to 1% among those first exposed after 1950. Thirteen surface workers with known exposure to arsenic had high rates of lung and stomach cancer. The SMR for lung cancer showed a consistent pattern in relation to duration of underground exposure, rising from 83 (observed/expected = 8/9.6) for surface workers (without exposure to arsenic) to 447 (15/3.4) for workers with more than 30 years underground exposure. Examination of the SMR for lung cancer by total underground exposure, age, and time since last exposure gave rise to a model for the expression of risk which depends only on total exposure and time since exposure. The fitted model implies that the effect of exposure to radon in a given year has no effect on risk for 10 years, then rapidly rises to a maximum from which the excess risk then declines, halving every 4.3 years. There were no direct measurements of historic radon levels. A conservative estimate based on measurements taken since 1969 by the National Radiological Protection Board and the Mines and Quarries Inspectorate is that the annual dose to an underground worker was about 10 working level months (WLM). Given this assumption, the risk/exposure slope implied by the present data, and the model fitted to it, was somewhat lower than that given in the fourth Committee on the Biological Effects of Ionisation Radiation (BEIR IV) report (about 40% lower for lifetime exposures). The present data also imply different risks depending on the age at exposure, with relatively higher lifetime risks for exposure at older ages, and relatively lower risks for exposures at younger ages. In conclusion, there was a clear relation between exposure to radon and death from lung cancer. The relative risk of lung cancer due to exposure to radon was not constant in cessation of exposure. The lifetime excess risk of lung cancer implied by these data for 40 years exposure at the current statutory limit of four WLM a year starting at age 20, was about 8% (79 excess deaths per 1000 exposed), assuming average smoking habits among the exposed workers. Control of dust concentrations in the mines has substantially reduced--and may have eliminated--direct mortality from silica related disease.     

Cohort-specific trends in stroke mortality in seven European countries were related to infant mortality rates

OBJECTIVES: To assess, in a population-based study, whether secular trends in cardiovascular disease mortality in seven European countries were correlated with past trends in infant mortality rate (IMR) in these countries. STUDY DESIGN AND SETTING: Data on ischemic heart disease (IHD) and stroke mortality in 1950-1999 in the Netherlands, England & Wales, France, and four Nordic countries were analyzed. We used Poisson regression to describe trends in mortality according to birth cohort, for the cohorts born between 1860 and 1939. Pearson correlation coefficients were calculated to determine associations between IMR and IHD, or stroke mortality. RESULTS: IHD mortality increased for successive cohorts up to 1900, and then started to decline. Stroke mortality levels were virtually stable among birth cohorts up to 1880, but declined rapidly among later cohorts. A strong positive association was found between cohort-specific IMR levels and stroke mortality rates. There were no strong cohort-wise associations between IMR and IHD mortality. CONCLUSION: These results support other studies in suggesting that living conditions in early childhood may influence population levels of stroke mortality. Future studies should determine the contribution of specific early life factors to the mortality decline in IHD and especially stroke.