Biomedical subjects
L Friberg
Publications and source records attributed to L Friberg.
[Medical effects of toxic metals in the environment].
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Assessment of exposure to lead and cadmium through biological monitoring: results of a UNEP/WHO global study.
This paper describes a UNEP/WHO project on the assessment of human exposure to lead and cadmium through analysis of blood and kidneys. The following countries have participated: Belgium, India, Israel, Japan, Mexico, People's Republic of China, Peru, Sweden, United States, and Yugoslavia. No laboratory started the monitoring before achieving satisfactory results of quality control (QC) analysis (samples of cow blood spiked with lead and cadmium and freeze-dried horse kidney cortex for cadmium analysis) according to predetermined criteria based on a linear regression model. Two hundred teachers from one urban area in each country constituted the target group for lead and cadmium in blood and cases of "sudden, unexpected death" for cadmium in kidney cortex. QC samples were analyzed in parallel with the monitoring samples to assure validity of the obtained results. The quality assurance program also included preanalytical quality control. There was considerable variation in metal exposure between areas. Geometric means for lead in blood ranged from about 60 micrograms Pb/liter in Beijing and Tokyo to 225 in Mexico City. The values were below 100 micrograms Pb/liter also in Baltimore, Jerusalem, Lima, Stockholm, and Zagreb, and between 100 and 200 micrograms Pb/liter in Brussels and India. In general, males had higher blood levels than females and smokers higher than nonsmokers. With a few exceptions the values were lower than results reported in a recent study within the European Communities. Geometric means for cadmium in blood ranged from 0.5 microgram Cd/liter in Stockholm and Jerusalem to 1.2 in Brussels and Tokyo. Cadmium levels were considerably higher among smokers than among nonsmokers. Tokyo had the highest values for cadmium in kidney cortex with a geometric mean in the age group 40-60 years of 60-70 mg Cd/kg wet wt. Lowest values were found in Baltimore, Beijing, India, and Jerusalem, with means around 20-25 mg Cd/kg wet wt. There was a tendency toward higher values for smokers than for nonsmokers, but no differences related to sex. Data were not received from Mexico and Peru.
Lead and cadmium levels in blood samples from the general population of Sweden.
Lead and cadmium was determined in whole blood samples obtained from 473 nonoccupationally exposed adult persons in Sweden in 1980. Analyses were performed using atomic absorption spectrophotometry equipped with an electrothermal atomization unit. Accuracy of the analysis was confirmed by the analysis of quality control samples. Blood lead concentrations were shown to be significantly influenced by sex, smoking habits, and alcohol consumption. Current male smokers had a median blood lead level of 92 micrograms Pb/liter, as compared to 77 micrograms Pb/liter for nonsmokers. For females the corresponding values were 69 micrograms Pb/liter and 57 micrograms Pb/liter for current smokers and nonsmokers, respectively. Highly significant correlations were found between stated alcohol consumption and blood lead in most of the different sex and smoking categories. People living in apartments close to streets with heavy traffic in Stockholm had slightly, but not significantly, higher blood lead levels when compared to people living in areas of this city with low traffic density. Blood cadmium levels were very strongly affected by smoking habits. A significant correlation existed between the number of cigarettes consumed daily and blood cadmium concentration. The median blood cadmium level for nonsmoking males was 0.2 micrograms Cd/liter (less than or equal to 0.2, detection limit) and for females 0.3 micrograms Cd/liter. About 90% of all nonsmokers had cadmium concentrations in blood below 0.6 micrograms Cd/liter, whereas about 90% of the current male and female smokers had cadmium concentrations in blood of 0.6 micrograms Cd/liter or more.
Evaluation of human and animal data in a comprehensive health assessment of energy systems.
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[Chloroquine poisoning. A review and a case of acute poisoning].
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[Alarm about cadmium -- is anxiety justified?].
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[The 1980's: how do we adjust the demand for a good environment against individual freedom of choice?].
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A twin methodology for the study of genetic and environmental control of variation in human smoking behavior.
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Mortality and cancer morbidity among cadmium-exposed workers.
Preliminary data are reported from a study of 269 cadmium-nickel battery factory workers and 94 cadmium-copper alloy factory workers. The target group comprises all workers with more than 5 years exposure to cadmium at any time since the factories started production. An internal reference group of 328 alloy factory workers without cadmium exposure was also studied. The expected number of deaths and cancers was calculated with the "life-table" method by using national average incidence rates for men in different age groups and at different calendar years. It was found that among the workers in the battery factory who started work before 1948 there was an increased general mortality in the 1950's mainly due to respiratory disease. The same group had an increased renal disease mortality. There was no increase in general cancer mortality or in general cancer incidence. The risk ratio for nasopharyngeal cancer incidence was 10 (two cases), which was statistically significant. For some other sites like prostate, lung and colon-rectum the risk ratios were also greater than 1 but not statistically significant. In the alloy factory there was a tendency for an increased mortality in prostatic cancer (four cases). After correction for the "healthy worker effect" using the reference group, the risk ratio for prostatic cancer deaths was calculated as 2.4, but this was not statistically significant. The findings in this study support the earlier reports of an association between human cadmium exposure and increased risk for prostatic cancer.
Late effects of air pollution with special reference to lung cancer.
The Department of Environmental Hygiene of the National Swedish Environment Protection Board and of the Karolinska Institute have prepared an extensive review on health effects of air pollution, to be used by the Swedish Parliamentary Committee on Energy and the Environment. This report forms the basis for one part of the review, that on late effects. Much of the work on the review, is the result of a team effort involving researchers from numerous organizations.
The interactions of smoking, environment and heredity and their implications for disease etiology. A report of epidemiological studies on the Swedish twin registries.
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Background of angina pectoris: social and environmental factors in relation to smoking.
Questionnaire data on about 1200 male twin pairs from the Registry at the Karolinska Institute, Stockholm, and on about 4000 male twin pairs from the Registry of the National Research Council, Washington, DC, have been used to study factors affecting angina pectoris. An operational definition of "angina pectoris" was developed from the questionnaire. In the available data, alcohol drinking, lack of exercise, frequent change of employer, low occupational adjustment and smoking are moderately but significantly related to angina among individuals (disregarding twin relationships) in both Sweden and the US. In monozygous US twin pairs discordant for the above variables, significantly different rates of angina appear only with alcohol drinking. In discordant dizygous US twin pairs, significantly different rates of angina appear with alcohol drinking and with low occupational adjustment. Of the independent variables only smoking and drinking are appreciably associated with each other. These findings suggest that alcohol drinking and to a lesser extent occupational adjustment are related to angina directly and not through their association with other factors such as age, genetic background, smoking, physical exercise and early environment.
A validation of cause-of-death certification in 1,156 deaths.
Swedish twins have been followed for mortality since 1961, when the Swedish Twin Registry was formed. During the years 1961-73 there were 1290 deaths among twins born in 1901-25. In 1156 cases the cause of death could be established from collected records and classified according to the 1965 revision of ICD. Using the review of records as the standard, rates of detection and confirmation relating to the death certificate diagnoses were calculated. It is concluded that Swedish death certificate data are fairly valid for use in epidemiological studies and mortality statistics with regard to most cancer forms, cerebrovascular disease, ischemic heart disease, bronchitis, asthma and emphysema, accidents and suicides, but not for diabetes mellitus, alcoholism, mental diseases, rheumatic heart diseases and other heart diseases. However, in selected clinical-epidemiological studies it is often necessary to collect all available documents prior to judging the cause of death.
A new Swedish twin registry containing environmental and medical base line data from about 14,000 same-sexed pairs born 1926-58.
Since the beginning of the 1960's the Department of Environmental Hygiene of the Karolinska Institute and of the National Swedish Environment Protection Board has maintained a registry on about 10.000 same-sexed twin-pairs born 1886-1925. The registry has been used for studies of morbidity and mortality against the background of certain external risk factors, especially smoking. Supported by the Research Committee of the National Swedish Environment Protection Board, the establishment of a new twin registry covering younger age cohorts was initiated in 1970. The main purposes of this registry are to evaluate individuals' adaptation to changes in the environment and to study the effects of the environment on human health. Moreover, the registry is intended to be usable in obtaining specific target groups with a certain exposure. The main reason for the establishment of a twin registry instead of using a representative sample from the entire population is that a twin population offers some additional analytical possibilities. With twins composing the study group, it is possible to assess the role of the genetic factor for different variables. In addition, the twin approach provides opportunities of analyzing the subjects as matched pairs--the twin control method. This method involves the evaluation of the effect of one factor, to which one twin in the pair is exposed and the other not, while other variables are kept constant in a far-reaching way, e.g. sex, age, genetic composition, childhood, environment, etc. A twin registry can also be employed as a general epidemiological base line registry. For such purposes, the twin methodology is ignored, and the effects of some agent, for example having to do with environmental hygiene, are studied on all of the individuals, independently of their twin pair qualities. The registry is then in many regards comparable with a registry of non-twins. The first step in creating the Swedish twin registry was to compile information on names and addresses. By means of searches in birth records for the years 1926-1949 and birth notices for the years 1950-1967, registration was made of ca 110 000 twin individuals, which constitute virtually all twins accounted for in official statistics. Of these, ca 13 800 were stillbirths or infant deaths. Before the search for the twins' current addresses was begun, all pairs in which at least one individual was dead were eliminated. Such was the case in ca 10 250 pairs. The address search hence covered about 89 500 individuals and was carried out with the assistance of two location procedures. The first was applied to those born between 1926 and 1949 and the second to those born between 1950 and 1967. The result was that in ca 96% of the pairs both members (37 590 pairs) or one member (4 853 pairs) could be found. It could be anticipated that of the latter pairs 1 450 would not be useable due to the death of one of the twins. The data collection has been carried out via a mail questionnaire which consists of the following main areas of inquiry: medication, annoyance experienced because of factors in the general and occupational environments, smoking and drinking habits, physical activity, food habits, psychosocial status, occupational and educational history, conditions of place of dwelling and certain background data. Before the questionnaire was sent out to the twin population, it was tested in a pilot investigation, which purported to study the effectiveness of the data collection procedure and to elucidate the validity of some of the individual questions. The pilot investigation showed an external nonresponse rate of 18%. Regarding the ability of the subjects to answer the questions, it was revealed that only a few of the question categories presented problems which gave rise to minor changes in the questionnaire. Comparison between the answers on the questionnaire and a parallel interview showed a high degree of agreement. Thus the questionnaire was considered satisfactory. The principal data collection was carried out during the period January - May 1973 and during the period December 1973 - February 1974. Of the 42 294 individuals included in the data collection, 3 339 could not be contacted because of death, illness etc. Responses have been received from 32 374 individuals, which corresponds to 83% of the subjects who could be contacted. Regarded as a population of twin pairs, 3 262 pairs have not been utilizable for similar reasons. The total number of pairs in which both have answered the questionnaire is 13 811, corresponding to a little over 77%. There are three versions of the twin registry; a birth registry, an address registry and a questionnaire registry. The birth registry contains birth data from about 110,000 twin individuals. The address registry contains in addition current information as to name and address as well as current and past census registration. The questionnaire registry, which comprises twins born 1926-1958, moreover contains information obtained on the basis of the mail questionnaire.