Inter-rater reliability of occupational exposure assessment in a case-control study of female breast cancer.

The objective of this paper was to estimate the inter-rater reliability of expert assessments of occupational exposures. An inter-rater reliability sub-study was conducted within a population-based case-control study of postmenopausal breast cancer. Detailed information on lifetime occupational histories was obtained from participants and two industrial hygienists assigned exposures to 185 jobs using a checklist of 293 agents. Experts rated exposure for each job-agent combination according to exposure status (unexposed/exposed), confidence that the exposure occurred (possible/probable/definite), intensity (low/medium/high), and frequency (% time per week). The statistical unit of observation was each job-agent assessment (185 jobs × 293 agents = 54,205 assessments per expert). Crude agreement, Gwet AC1/2 statistics, and Cohen's Kappa were used to estimate inter-rater agreement for confidence and intensity; for frequency, the intra-class correlation coefficient (ICC) was used. The majority of job-agent combinations were evaluated by the two experts to be not exposed (crude agreement >98% of decisions). The degree of agreement between the experts for the confidence of exposure status was Gwet AC1/2 = 0.99 (95% CI: 0.99-0.99), and for intensity, a Gwet AC2 = 0.99 (95% CI: 0.99-0.99). For frequency, an ICC of 0.31 (95% CI: 0.26-0.35) was found. A sub-analysis restricted to job-agent combinations for which the two experts agreed on exposure status revealed a moderate agreement for confidence of exposure (Gwet AC2 = 0.66) and high agreement for intensity (Gwet AC2 = 0.96). For frequency, the ICC was 0.52 (95% CI: 0.47-0.57). A high level of inter-rater agreement was found for identifying exposures and for coding intensity, but agreement was lower for the coding of frequency of exposure.

Is there a cause-and-effect relationship between alpha-synuclein fibrillization and Parkinson's disease?

The first gene to be linked to Parkinson's disease encodes the neuronal protein alpha-synuclein. Recent mouse and Drosophila models of Parkinson's disease support a central role for the process of alpha-synuclein fibrillization in pathogenesis. However, some evidence indicates that the fibril itself may not be the pathogenic species. Our own biophysical studies suggest that a structured fibrillization intermediate or an alternatively assembled oligomer may be responsible for neuronal death. This speculation can now be experimentally tested in the animal models. Such experiments will have implications for the development of new therapies for Parkinson's disease and related neurodegenerative diseases.

A panel study in congestive heart failure to estimate the short-term effects from personal factors and environmental conditions on oxygen saturation and pulse rate.

OBJECTIVES: Recent studies suggest that persons with congestive heart failure (CHF) may be at higher risk for short-term effects of air pollution. This daily diary panel study in Montreal, Quebec, was carried out to determine whether oxygen saturation and pulse rate were associated with selected personal factors, weather conditions and air pollution. METHODS: Thirty-one subjects with CHF participated in this study in 2002 and 2003. Over a 2-month period, the investigators measured their oxygen saturation, pulse rate, weight and temperature each morning and recorded these and other data in a daily diary. Air pollution and weather conditions were obtained from fixed-site monitoring stations. The study made use of mixed regression models, adjusting for within-subject serial correlation and temporal trends, to determine the association between oxygen saturation and pulse rate and personal and environmental variables. Depending on the model, we accounted for the effects of a variety of personal variables (eg, body temperature, salt consumption) as well as nitrogen dioxide (NO2), ozone, maximum temperature and change in barometric pressure at 8:00 from the previous day. RESULTS: In multivariable analyses, the study found that oxygen saturation was reduced when subjects reported that they were ill, consumed salt, or drank liquids on the previous day and had higher body temperatures on the concurrent day (only the latter was statistically significant). Relative humidity and decreased atmospheric pressure from the previous day were associated with oxygen saturation. In univariate analyses, there was negative associations with concentrations of fine particulates, ozone, and sulphur dioxide (SO2), but only SO2 was significant after adjustment for the effects of weather. For pulse rate, no associations were found for the personal variables and in univariate analyses the study found positive associations with NO(2), fine particulates (aerodynamic diameter of 2.5 microm or under, PM(2.5)), SO2, and maximum temperature, although only the latter two were significant after adjustment for environmental effects. CONCLUSIONS: The findings from the present investigation suggest that personal and environmental conditions affect intermediate physiological parameters that may affect the health of CHF patients.

Immunoglobulin G3 subclass production by rheumatoid synovial tissue cultures.

The cellular infiltrate in the deeper layers of the rheumatoid synovium produces a substantial amount of immunoglobulin (Ig)G. Culture supernatants of synovial tissues from 31 patients with rheumatoid arthritis (RA) undergoing joint replacement or synovectomy have been analyzed for the subclass of IgG present. IgG3 was measured by separation with Staphylococcal Protein A chromatography, precipitation with specific anti-IgG3 antibody, and differential separation of IgG3 heavy chains using polyacrylamide gel electrophoresis. IgG from RA synovial cultures contained an average of 41% IgG3 (range, 8-97%) compared with 12% IgG3 (range, 6-17%) in the serum IgG of the same patients. A group of non-RA control lymphoid tissues (four lymph nodes and five tonsils) produced 23% of total IgG as the IgG3 subclass (range, 16-35%). An average of only 9% of the synovial IgG showed aggregation compatible with IgG-rheumatoid factor (IgG-RF). Purified IgG from some of the RA synovial culture supernatants also showed significant restriction when separated by isoelectric focusing. This restriction and the enrichment for the IgG3 subclass in the IgG from RA synovial cultures suggest that either an antigen in the inflamed joint is selectively stimulating an antibody in this subclass, or that significantly differences in the catabolic rate of this subclass are found in cultures of synovial tissue when compared with that occurring in intact patients.

The solution structure of eglin c based on measurements of many NOEs and coupling constants and its comparison with X-ray structures.

A high-precision solution structure of the elastase inhibitor eglin c was determined by NMR and distance geometry calculations. A large set of 947 nuclear Overhauser (NOE) distance constraints was identified, 417 of which were quantified from two-dimensional NOE spectra at short mixing times. In addition, a large number of homonuclear 1H-1H and heteronuclear 1H-15N vicinal coupling constants were used, and constraints on 42 chi 1 and 38 phi angles were obtained. Structure calculations were carried out using the distance geometry program DG-II. These calculations had a high convergence rate, in that 66 out of 75 calculations converged with maximum residual NOE violations ranging from 0.17 A to 0.47 A. The spread of the structures was characterized with average root mean square deviations () between the structures and a mean structure. To calculate the unbiased toward any single structure, a new procedure was used for structure alignment. A canonical structure was calculated from the mean distances, and all structures were aligned relative to that. Furthermore, an angular order parameter S was defined and used to characterize the spread of structures in torsion angle space. To obtain an accurate estimate of the precision of the structure, the number of calculations was increased until the and the angular order parameters stabilized. This was achieved after approximately 40 calculations. The structure consists of a well-defined core whose backbone deviates from the canonical structure ca. 0.4 A, a disordered N-terminal heptapeptide whose backbone deviates by 0.8-12 A, and a proteinase-binding loop whose backbone deviates up to 3.0 A. Analysis of the angular order parameters and inspection of the structures indicates that a hinge-bending motion of the binding loop may occur in solution. Secondary structures were analyzed by comparison of dihedral angle patterns. The high precision of the structure allows one to identify subtle differences with four crystal structures of eglin c determined in complexes with proteinases.

The spatial association between community air pollution and mortality: a new method of analyzing correlated geographic cohort data.

We present a new statistical model for linking spatial variation in ambient air pollution to mortality. The model incorporates risk factors measured at the individual level, such as smoking, and at the spatial level, such as air pollution. We demonstrate that the spatial autocorrelation in community mortality rates, an indication of not fully characterizing potentially confounding risk factors to the air pollution-mortality association, can be accounted for through the inclusion of location in the model assessing the effects of air pollution on mortality. Our methods are illustrated with an analysis of the American Cancer Society cohort to determine whether all cause mortality is associated with concentrations of sulfate particles. The relative risk associated with a 4.2 microg/m(3) interquartile range of sulfate distribution for all causes of death was 1.051 (95% confidence interval 1.036-1.066) based on the Cox proportional hazards survival model, assuming subjects were statistically independent. Inclusion of community-based random effects yielded a relative risk of 1.055 (1.033, 1.077), which represented a doubling in the residual variance compared to that estimated by the Cox model. Residuals from the random-effects model displayed strong evidence of spatial autocorrelation (p = 0.0052). Further inclusion of a location surface reduced the sulfate relative risk and the evidence for autocorrelation as the complexity of the location surface increased, with a range in relative risks of 1.055-1.035. We conclude that these data display both extravariation and spatial autocorrelation, characteristics not captured by the Cox survival model. Failure to account for extravariation and spatial autocorrelation can lead to an understatement of the uncertainty of the air pollution association with mortality.

Identification of persons with cardiorespiratory conditions who are at risk of dying from the acute effects of ambient air particles.

This study was undertaken to identify subgroups of the population susceptible to the effects of ambient air particles. Fixed-site air pollution monitors in Montreal, Quebec, Canada, provided daily mean levels of various measures of particulates and gaseous pollutants. Total sulfates were also measured daily (1986-1993) at a monitoring station 150 km southeast of the city (Sutton, Quebec, Canada). We used coefficient of haze (COH), extinction coefficient, and Sutton sulfates to predict fine particles and sulfates from a fine particles model for days that were missing. We used the universal Quebec medicare system to obtain billings and prescriptions for each Montreal resident who died in the city from 1984 to 1993. These data were then used to define cardiovascular and respiratory conditions that subjects had before death. Using standard Poisson regression time-series analyses, we estimated the association between daily nonaccidental mortality and daily concentrations of particles in the ambient air among persons with cardiovascular and respiratory conditions diagnosed before death. We found no persuasive evidence that daily mortality increased when ambient air particles were elevated for subgroups of persons with chronic upper respiratory diseases, airways disease, cerebrovascular diseases, acute coronary artery disease, and hypertension. However, we found that daily mortality increased linearly as concentrations of particles increased for persons who had acute lower respiratory diseases, chronic coronary artery diseases (especially in the elderly), and congestive heart failure. For this latter set of conditions, the mean percent increase in daily mortality (MPC) for an increase in the COH across its interquartile range (18.5 COH units per 327.8 linear meters), averaged over the day of death and the 2 preceding days, was MPC = 5.09% [95% confidence interval (CI) 2.47-7.79%], MPC = 2.62 (95% CI 0.53-4.75%), and MPC = 4.99 (95% CI 2.44-7.60%), respectively. Adjustments for gaseous pollutants generally attenuated these associations, although the general pattern of increased daily mortality remained. In addition, there appeared to be a stronger association in the summer season. The positive associations found for persons who had acute lower respiratory diseases and congestive heart failure are consistent with some prevailing hypotheses and may also be consistent with recent toxicologic data implicating endothelins. Further epidemiologic studies are required to confirm these findings.

Statistical assessment of ordinal outcomes in comparative studies.

Ordinal regression is a relatively new statistical method developed for analyzing ranked outcomes. In the past, ranked scales have often been analyzed without making full use of the ordinality of the data or, alternatively, by assigning arbitrary numerical scores to the ranks. While ordinal regression models are now available to make full use of ranked data, they are not used widely. This article, directed to clinical researchers and epidemiologists, provides a description of the properties of these methods. Using ordinal measures of back pain in a follow-up study of adolescent idiopathic scoliosis, we illustrate the advantages of those methods and describe how to interpret the estimated parameters. Comparisons with binary logistic regression are made to show why a single dichotomization of the ordinal scale may lead to incorrect inferences. Two ordinal models (the proportional odds and the continuation ratio models) are discussed, and the goodness-of-fit of these models is examined. We conclude that ordinal regression is a tool that is powerful, simple to use, and produces an interpretable parameter that summarizes the effect between groups over all levels of the outcome.

Exposure to environmental tobacco smoke and the risk of lung cancer: a meta-analysis.

A meta-analysis was carried out to calculate a pooled estimate of relative risk of lung cancer following exposure to environmental tobacco smoke (ETS) and to determine whether there was any heterogeneity in the pooled estimates according to selected characteristics of the studies. A total of 35 case-control and five cohort studies providing quantitative estimates of the association between lung cancer and exposure to ETS published between January 1981 and March 1999 were identified. Using fixed- and random-effects models, we calculated pooled estimates of relative risk for exposure to ETS from subjects' parents (during childhood), spouses, and coworkers. As well, we investigated whether the pooled estimates of relative risk varied by study location, degree of control of potential confounding variables, proportion of cases confirmed histologically, proportion of surrogate respondents, nonresponse rates, and year of publication. The relative risk of lung cancer among non smoking women ever exposed to ETS from their husbands' smoking was 1.20 (95% confidence interval (CI): 1.12-1.29). The pooled relative risk was 1.19 (95% CI: 1.10-1.29) for case-control studies and 1.29 (95% CI: 1.04-1.62) for cohort studies. In various subgroup and meta-regression analyses, we found no statistically significant differences by selected characteristics of the studies. In addition, we found that the risk of lung cancer increased consistently with increasing levels of exposure. The 11 studies reporting relative risks among male non smokers yielded a pooled relative risk of 1.48 (95% CI: 1.13-1.92) for ever exposed to ETS, and the relative risk of lung cancer for ever being exposed to ETS at work was a 1.16 (95% CI: 1.05-1.28). These results are consistent with the hypothesis that exposure to ETS increases the risk of lung cancer. While there may be alternative explanations to the data, it is more likely that the observed association is not an artifact and that ETS causes lung cancer in non smokers.

Examination of amniotic fluid in diagnosing congenital syphilis with fetal death.

The diagnosis of congenital syphilis is difficult, particularly in stillborn fetuses, who are often macerated and have undergone autolysis. These changes can obscure both syphilitic histologic findings and special stains for spirochetes in tissue specimens used to confirm the diagnosis of congenital syphilis. Five gravidas with untreated syphilis and fetal deaths underwent sonographic examination and amniocentesis. In all five cases, dark-field microscopic examination of the amniotic fluid showed spirochetes with morphology and motility characteristic of Treponema pallidum. Organisms were infrequent, but easily identified at 400x magnification and confirmed using an oil-immersion objective yielding a 900x magnification. After delivery, fetal-placental examination and autopsy showed clinical findings typical of congenital syphilis in all five cases. Histologic changes compatible with syphilis were found in all four autopsied fetuses. Silver impregnation stains were positive in two of five tissue specimens, and anti-treponemal monoclonal antibody immunofluorescence assays were positive in one of three amniotic fluid specimens examined retrospectively, further strengthening the specificity of the dark-field microscopic identification of spirochetes. This technique, which can make the diagnosis of congenital syphilis, is recommended for women with syphilis and a fetal death, especially if sonographic hydrops and/or edema is present or if an autopsy will not be performed.

A review of the association between cigarette smoking and the development of nonspecific back pain and related outcomes.

STUDY DESIGN: A structured review of the epidemiologic literature was performed. Thirty-eight studies published in peer-reviewed journals were reviewed. The methodologic strengths and weaknesses of the studies were described and assessed qualitatively. Four studies were excluded because of difficulties in design or interpretation. OBJECTIVES: To provide a systematic analysis of the literature to assess the evidence as to whether smoking is associated with the prevalence and incidence of nonspecific back pain and related outcomes. SUMMARY OF BACKGROUND DATA: Evidence has been gathering regarding the association of smoking with nonspecific back pain and other back disorders, but a comprehensive summary and evaluation of the data have not been published. RESULTS: Positive associations between current smoking and nonspecific back pain were found in 18 of 26 studies in men and 18 of 20 studies in women. For sciatica and herniated discs, there were four of eight and one of five positive studies in men and women, respectively. The majority of these studies were cross-sectional (18 in men and 16 in women), with only a handful of prospective studies. Positive associations between past smoking and nonspecific back pain were reported in five of nine studies in men and five of six studies in women. In addition, increases in the prevalence and/or incidence of nonspecific back pain were found in the majority of studies in which level of consumption was analyzed and reported. An attempt was made to assess whether these results could be artifactual arising from selection bias, confounding bias, publication bias, or errors in measurement. As well, the biologic mechanisms were summarized that have been suggested by various investigators. CONCLUSIONS: The available data are consistent with the notion that smoking is associated with the incidenceand prevalence of nonspecific back pain, but there are too few studies to make any conclusions for the other end points (e.g., sciatica, herniated discs). It cannot be ruled out that the association is a statistical artifact arising from either selection or confounding factors, because the evidence for nonspecific low back pain derives mostly from cross-sectional studies. In addition, it cannot be stated unequivocally that smoking preceded back pain. Long-term follow-up studies are needed to eliminate the possibility that chronic back pain preceded smoking, to better estimate dose-response correlations, and to perform biologic measurements to elucidate possible mechanisms.

Observer variation in assessing spinal curvature and skeletal development in adolescent idiopathic scoliosis.

Accurate measurements of spinal curvature and skeletal development are crucial in planning treatment and assessing curve progression in adolescent idiopathic scoliosis (AIS). An inter-rater agreement trial was undertaken to estimate the reliability of measuring these spinal parameters. Two orthopaedic surgeons and two trained technicians from a scoliosis clinic independently read 30 anteroposterior roentgenograms of AIS patients. Skeletal maturity was assessed using the six-point Risser sign scale, and spinal curvature was measured using the method of Cobb. Excellent agreement was observed in evaluating Risser signs (Kappa = 0.8) and primary Cobb angles (intra-class correlation coefficient, Rho = 0.98). The standard deviation of inter-observer error in measuring primary Cobb angles was 2.5 degrees, and the intra-reader error, based on one observer's reassessments of 15 films, was 1.9 degrees. Inter-rater agreement for assessing secondary Cobb angles was much lower (Rho = 0.52) because small curves (less than 20 degrees) were often not noticed. Differences in agreement between surgeons and technicians were relatively minor. These results indicate that personnel trained at this clinic are able to assess these spinal parameters reliably.

The association between cigarette smoking and back pain in adults.

STUDY DESIGN: A retrospective cohort study of adolescent idiopathic scoliosis. A comparison group of persons without scoliosis was also selected randomly from the general population. OBJECTIVES: To estimate the association between level of cigarette smoking and the prevalence and severity of back pain. METHODS: A postal questionnaire was used to elicit information on smoking histories, a variety of indices of low back pain, and potential confounding factors. The association between smoking and back pain was estimated separately for men and women in the cohort and in the comparison group using ordinal regression models. RESULTS: The questionnaire was completed by 1287 women and 184 men who had adolescent idiopathic scoliosis and by 1130 women and 621 men in the comparison population who did not have scoliosis. Statistically significant associations between back pain and current cigarette smoking were found in the two groups of women and men with scoliosis, but not among men selected from the general population. In the three former groups, proportional odds ratios comparing current smokers to persons who never smoked ranged from 1.4 to 1.9. Among current smokers, the prevalence of back pain increased with cigarette consumption, and the proportional odds ratios ranged from 1.2 to 1.8 per 10 pack-years (no. of cigarettes smoked per day x no. of years/20). In these three groups, intensity, frequency, and duration of episodes of back pain also were found to increase with smoking consumption. CONCLUSION: The finding that smokers have more frequent episodes of back pain may imply that smoking exacerbates back pain, and the observation that stronger associations between back pain and smoking were found in the scoliosis cohort suggests that smoking may have a greater impact on persons with damaged spines.

The Ste-Justine Adolescent Idiopathic Scoliosis Cohort Study. Part II: Perception of health, self and body image, and participation in physical activities.

OBJECTIVES: This study determined the health and well being of persons with adolescent idiopathic scoliosis (AIS) more than 10 years after referral. This communication will present results related to the perception of health, self and body image, and difficulty with selected physical activities. STUDY DESIGN: The study was designed as a comparative retrospective cohort study. Subjects referred for AIS between 1960 and 1979 to a large pediatric hospital in Montreal, Quebec were entered in the cohort. A population-based control group was selected from the general population of Quebec at the time of survey. METHODS: Health outcomes were assessed by a postal questionnaire administered to the AIS cohort and to the control group. Most outcomes were ordinal and, thus, odds ratios were estimated using ordinal regression while adjusting for potential confounding factors. RESULTS: AIS subjects, particularly those who were surgically treated, had a significantly higher prevalence of self-reported arthritis. Scoliosis subjects perceived themselves to be less healthy than other persons the same age and, particularly among women, scoliosis subjects had a poorer perception of body image, and had more physician visits and days ill than control subjects. In addition, male and female AIS subjects had more difficulty with physical activities. This rather negative perception of health could be a result of actual illness or a result of more concern about illness. Nevertheless, they had a more positive perception of self and appeared to be able to cope with their affliction and disfigurement in a positive way.

The Ste-Justine Adolescent Idiopathic Scoliosis Cohort Study. Part I: Description of the study.

OBJECTIVES: This study determined the impact of adolescent idiopathic scoliosis (AIS) on health and well being in adulthood by comparing AIS subjects, more than 10 years after referral, to non-AIS subjects according to perceived health status, physical activity, fitness, reproductive health, respiratory condition, and back and neck pain. This paper describes the cohort, the design of the study, and response rates. STUDY DESIGN: The study was designed as a comparative retrospective cohort study. A total of 2,092 patients referred for AIS to Ste-Justine Hospital, Montreal, Quebec, between 1960 and 1979 were identified. A population-based control group was selected in 1989-90 by randomly telephoning persons in Quebec. The control group was approximately frequency-matched to the AIS cohort according to age group and broad geographic region of current residence. METHODS: Patients with adolescent idiopathic scoliosis were traced, and a self-administered questionnaire was sent by post in 1989 to subjects whose addresses were found. Identical questionnaires were sent to subjects in the control group. RESULTS: Seventy-one percent of the cohort (1,476 subjects) returned questionnaires in 1989. Subjects who did not respond to the questionnaires were similar to those who did complete the questionnaires on a number of key factors, except that lower response rates were observed for subjects with scoliotic curves under 20 degrees. The control group consisted of 1,755 subjects (55% response rate). It was similar to the general Quebec population and to the AIS cohort on a number of important sociodemographic factors. CONCLUSION: Comparisons on health outcomes between the two study groups should not be affected by differential patterns of selection or response.

The Ste-Justine Adolescent Idiopathic Scoliosis Cohort Study. Part III: Back pain.

OBJECTIVES: This study determined health and well being of persons with adolescent idiopathic scoliosis (AIS) more than 10 years after referral. This communication will present results related to back pain. STUDY DESIGN: This study was designed as a comparative retrospective cohort study. Subjects referred for AIS between 1960 and 1979 to a large pediatric hospital in Montreal, Quebec, were entered into the cohort. A population-based control group was selected from the general population of Quebec using a telephone survey. METHODS: Back pain was assessed by postal questionnaires administered, in 1990, to the AIS cohort and to the control group. Most outcomes were ordinal and, thus, odds ratios were estimated using ordinal regression while adjusting for potential confounding factors. RESULTS: Among the 1,476 AIS subjects responding, 73% experienced one or more episodes of back pain in the past year, significantly more than the 1,755 controls (56%); for current back pain, these proportions were also significantly different: 44% for AIS subjects and 24% for controls. In comparison to controls, AIS subjects reported pain that was more intense, continuous, generalized throughout the back, and radiating into the extremities. AIS subjects were also more restricted in many usual daily activities. Little variability was observed in the prevalence of current back pain and back pain in the past year according to treatment and degree of curvature. Difficulty with managing pain, lifting, walking, and socializing was, however, associated with severity. The results of this study suggest that back pain is responsible for a considerable amount of disability and handicap in later life. Health professionals involved with the management of persons with AIS need to consider this important outcome and need to put in place procedures for the identification, investigation, prevention, and treatment of back pain.

The Ste-Justine Adolescent Idiopathic Scoliosis Cohort Study. Part IV: Surgical correction and back pain.

OBJECTIVES: This study determined whether the prevalence, nature, and consequences of back pain in adulthood among persons who underwent Harrington rod instrumentation was related to the number of vertebrae fused, distal level of hook insertion, and degree of correction. STUDY DESIGN: This study was designed as a comparative retrospective cohort study. Subjects referred for AIS between 1960 and 1979 to a large pediatric hospital in Montreal, Quebec, were entered into the cohort. A population based control group was selected from the general population of Quebec using a telephone survey. METHODS: Back pain was assessed by postal questionnaire administered in 1990. Data was analyzed using two multivariate regression models: relative risk regression for dichotomous outcomes and ordinal regression for outcomes measured on an ordinal scale. RESULTS: Among the 723 AIS subjects who had surgery at Ste. Justine's Hospital, 555 completed the questionnaire on back pain. Overall, 73% of patients treated surgically reported back pain in the past year. Proportions varied little by presurgery characteristics or by degree of surgical correction. The distal level of fusion did not influence, in any consistent way, the occurrence of back pain in later life nor the degree of disability associated with back pain. This study does not provide any evidence that extending the level of fusion down even as far as L4 will increase the prevalence of back pain in adulthood.

Reducing the lifetime risk of cancer from spinal radiographs among people with adolescent idiopathic scoliosis.

STUDY DESIGN: Data from a retrospective cohort study of people with adolescent idiopathic scoliosis were combined with information on full-spinal radiographs to estimate contemporary x-ray doses and lifetime risks for development of cancer. OBJECTIVES: To project the lifetime risk for development of cancer from diagnostic radiographs for people with adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Although a twofold excess risk for breast cancer has been reported for women treated for scoliosis between 1925 and 1965, information on the cancer risks associated with scoliosis management today is sparse. Specifically, there is a lack of up-to-date information on the number of spinal radiographs taken, the organ-specific x-ray doses from current radiographic techniques, and the projected cancer risks. METHODS: The cohort consisted of subjects with adolescent idiopathic scoliosis who were referred to the scoliosis clinic of a large pediatric hospital between 1965 and 1979 in Montreal, Quebec, Canada. Based on radiographic equipment and practices implemented in 1982, organ-specific x-ray doses to the thyroid gland, female breast, respiratory organs, digestive organs, and bone marrow were calculated using Monte Carlo methods. These doses were incorporated into a life table procedure to calculate theoretic lifetime cancer risks. For all organs except the thyroid gland, dose-response models from the United States National Academy of Sciences Fifth Committee on the Biological Effects of ionizing Radiation were used. For thyroid cancer, a risk model was derived from a study of thyroid cancer incidence after x-ray treatment for tinea capitis. RESULTS: The average number of spinal radiographs was 12 for women (80% anteroposterior or posteroanterior) and 10 for men (78% anteroposterior or posteroanterior). Cumulative x-ray doses were in general higher in adolescents who were referred as younger teenagers than at later ages, and doses increased with the size of the spinal curve. Depending on the age at referral and curve size, the total excess lifetime cancer risks were calculated to range from 42 to 238 cases per 100,000 women and 14 to 79 cases per 100,000 men. For subjects who underwent surgery (those exposed to the highest doses), the lifetime number of cancer cases over and above background was almost as great as the number of thyroid cancers that would occur in the absence of radiation exposure. If the anteroposterior view was replaced by the posteroanterior view, a three- to sevenfold reduction in cumulative doses to the thyroid gland and the female breast would be achieved, yielding three- to fourfold reductions in the lifetime risk of breast cancer and a halving of the lifetime risk of thyroid cancer. CONCLUSIONS: The cancer risks from full-spinal radiographs for scoliosis are not negligible and can be reduced from one half to three quarters if the anteroposterior view is replaced with the posteroanterior view.

Risk of developing lung cancer in relation to exposure to fumes from Chinese-style cooking.

In an evaluation of the association between exposure to indoor air pollution from Chinese-style cooking and the risk of lung cancer, epidemiologic and experimental studies were reviewed. The 9 case-referent studies that were identified showed consistent positive associations between the risk of lung cancer and a variety of indices of exposure to indoor air pollution arising from Chinese-style cooking. Three experimental studies showed that volatile emissions from oils heated in woks are mutagenic in several in vitro short-term test systems. Several toxic agents, including some accepted or suspected carcinogens, have been detected in the emissions of the heated cooking oils. While experimental data support the epidemiologic data, it may be premature to conclude that the association is causal. However, simple precautions can be taken to reduce the risk in the event that exposure to indoor air pollution arising from Chinese-style cooking is indeed a cause of lung cancer.

Epidemiology of occupational and environmental risk factors related to ovarian cancer.

This paper reviews articles published during 1970-1997 from 48 epidemiologic studies on occupational and environmental risk factors of ovarian cancer. Current evidence is characterized by poorly focused data for occupational and environmental agents, vulnerability to biases, and an almost complete lack of quantitative exposure-response data. The moderate amount of data on nurses, teachers, professionals, dry cleaning employees, women in agriculture, the pharmaceutical industry, pharmacists, waitresses, and cooks show very little, if any, evidence of excess risk. Hairdressers, beauticians, and women employed in the printing industry may be at increased risk, but the data are insufficient for strong conclusions. Some case-referent studies suggest a modest-to-moderate excess in association with genital talc application. Few high-quality studies have been carried out, and no chemical agents have been studied extensively, with the exception of exposure to talc. Ovarian cancer may have occupational and environmental etiologies intertwined with cultural, behavioral, and life-style factors and genetic susceptibility, but current knowledge is insufficient to quantify occupational and environmental etiologies reliably. Well-designed analytic epidemiologic studies with sufficient power are needed.