Community-based Case-control Studies Research Articles

Respirable crystalline silica and lung cancer in community-based studies: impact of job-exposure matrix specifications on exposure-response relationships.

The quantitative job-exposure matrix SYN-JEM consists of various dimensions: job-specific estimates, region-specific estimates, and prior expert ratings of jobs by the semi-quantitative DOM-JEM. We analyzed the effect of different JEM dimensions on the exposure-response relationships between occupational silica exposure and lung cancer risk to investigate how these variations influence estimates of exposure by a quantitative JEM and associated health endpoints. Using SYN-JEM, and alternative SYN-JEM specifications with varying dimensions included, cumulative silica exposure estimates were assigned to 16 901 lung cancer cases and 20 965 controls pooled from 14 international community-based case-control studies. Exposure-response relationships based on SYN-JEM and alternative SYN-JEM specifications were analyzed using regression analyses (by quartiles and log-transformed continuous silica exposure) and generalized additive models (GAM), adjusted for age, sex, study, cigarette pack-years, time since quitting smoking, and ever employment in occupations with established lung cancer risk. SYN-JEM and alternative specifications generated overall elevated and similar lung cancer odds ratios ranging from 1.13 (1st quartile) to 1.50 (4th quartile). In the categorical and log-linear analyses SYN-JEM with all dimensions included yielded the best model fit, and exclusion of job-specific estimates from SYN-JEM yielded the poorest model fit. Additionally, GAM showed the poorest model fit when excluding job-specific estimates. The established exposure-response relationship between occupational silica exposure and lung cancer was marginally influenced by varying the dimensions of SYN-JEM. Optimized modelling of exposure-response relationships will be obtained when incorporating all relevant dimensions, namely prior rating, job, time, and region. Quantitative job-specific estimates appeared to be the most prominent dimension for this general population JEM.

Correlation between IL-35 and viral load in patients with liver hepatitis type B in Baghdad

Hepatitis, including autoimmune hepatitis, alcoholic hepatitis, drug-induced hepatitis, bacterial hepatitis, viral hepatitis, and others, was a typical occurrence in clinical work. Hepatitis B virus (HBV) and hepatitis C virus (HCV), both non-cytopathic viruses, were shown to be frequent in liver damage. It has been observed that IL-35 is linked to a reduction in inflammation and can limit T-cell proliferation and the activity of its effector cells. The hepatitis B virus is a virus that causes liver disease. Serum IL-35 was shown to be higher in chronic hepatitis B virus patients. At the same time, research has discovered that Tregs and other cell types (such as activated myeloid, endothelial cells, and regulatory B cells) can secrete IL-35. The quantity of specific viral DNA or RNA in a blood sample is known as viral load count, and it is one of the potential biomarkers of hepatitis. A high viral load suggests that the immune system has failed to combat viruses. Real-time quantification of hepatitis B (HBV) DNA viral load is possible. Hepatic chronic, cirrhosis, and undetected patients are measured using polymerase chain reaction (PCR) and non-invasive methods. In the ordinary course of HBV infection, HBV DNA is the only thing that survives. HBV DNA levels represent viral levels and derive from mature infectious particles. Reproducibility. Various hospital-based and community-based case-control and cohort studies have repeatedly demonstrated substantial correlations between blood HBV DNA levels and the risk of liver cirrhosis and HCC. Chronic hepatitis B has a variable course in disease activity with a risk of clinical complications like liver cirrhosis and hepatocellular carcinoma. As clinical symptoms present in a late stage of the disease, identifying risk factors is important for early detection and, therefore, improving prognosis. Recently, two REVEAL-HBV studies from Iraq have shown a positive correlation between viral load at any point in time and the development of cirrhosis and hepatocellular carcinoma. Keywords: Hepatitis B virus HBV, Interleukin-35 IL-35, polymerase chain reaction PCR.

Early-life Chronic Stressors, Rumination, and the Onset of Vulvodynia

IntroductionVulvodynia is a debilitating, chronic vulvar pain condition. Community-based case-control studies have consistently shown associations between early-life chronic stressors and vulvodynia onset. AimWe examined rumination as a specific stress response involved in the psychobiological mechanism of vulvodynia. MethodsA psychosocial survey with questions specific to early-life traumatic events and rumination were administered to 185 matched case-control pairs of women with and without vulvodynia. Conditional logistic regression was used to examine associations between rumination constructs (ie, total rumination, emotion-focused, instrumental, and searching for meaning) and vulvodynia onset. Conditional logistic regression was also used to determine whether these associations depended on early-life stressors (ie, severity of childhood abuse and of self-reported antecedent traumatic events). Age at interview, antecedent pain disorders, any childhood abuse, and antecedent psychiatric morbidity were included as covariates. Main Outcome MeasuresWe estimated the odds of rumination in relation to the onset of vulvodynia within a community-based and clinically confirmed sample of women with and without vulvodynia. ResultsVulvodynia was associated with the highest tertile of emotion-focused (odds ratio [OR] = 2.1; 95% CI = 1.2, 3.2) and instrumental (OR = 2.1; 95% CI = 1.1, 4.0) rumination. These associations were attenuated after additional adjustment for antecedent psychiatric morbidity. Among women who reported rumination about early-life stressors before vulvar pain in cases or matched reference age in control subjects, those with vulvodynia were >2 times more likely to report the highest tertile of total rumination (OR = 2.3; 95% CI = 1.1, 5.0) compared with those without vulvodynia. Clinical ImplicationsHealthcare providers may be able to identify subsets of women who could benefit from preventive measures before the development of vulvodynia. Strength & LimitationsThis is the first study to use a community-based and clinically confirmed sample of women with and without vulvodynia to examine the associations between rumination about early-life trauma and the onset of vulvodynia. However, as with all retrospective studies, the reporting of information (eg, traumatic events) was subject to recall bias and misclassification. ConclusionOur findings indicate that a prolonged cognitive stress response (ie, rumination) may be 1 important mechanism by which early-life chronic stressors contribute to the onset vulvodynia. Prospective studies are recommended to examine whether and how cognitive, affective, and physiological components of prolonged stress responses interact to influence the development of vulvodynia. Understanding both the psychobiological and behavioral mechanisms may help in addressing and treating individuals to potentially reverse the development of vulvodynia.Khandker M, Brady SS, Rydell SA, et al. Early-life Chronic Stressors, Rumination, and the Onset of Vulvodynia. J Sex Med 2019;16:880–890.

Environmental exposure to BDE47 is associated with increased diabetes prevalence: Evidence from community-based case-control studies and an animal experiment.

Brominated flame retardants exposure has been associated with increasing trends of diabetes and metabolic disease. Thus, the purpose of this study was to provide evidence of polybrominated diphenyl ethers (PBDEs) exposure in relation to diabetes prevalence and to reveal the potential underlying mechanism in epidemiological and animal studies. All the participants received a questionnaire, health examination, and the detection of 7 PBDE congeners in serum in two independent community-based studies from 2011 to 2012 in China. Male rats were exposed to 2,2’4,4’-tetrabromodiphenyl ether (BDE47) for 8 weeks to explore its effects on glucose homeostasis and potential mechanisms using high-throughput genomic analysis. Among the 7 congeners, BDE47 showed significant high detection rate and concentration in cases in Study I and Study II. Every tertile of BDE47 exposure significantly increased the risk of diabetes prevalence in Study I (Ptrend = 0.001) and Study II (Ptrend < 0.001). Additionally, BDE47 treatments induced hyperglycemia in rats. Furthermore, gene microarray analysis showed that diabetes pathway and three gene ontology terms involved in glucose transport were enriched. The results indicated that environmental exposure to BDE47 was associated with increased diabetes prevalence. However, further prospective and mechanistic studies are needed to the causation of diabetes in relation to BDE47.

0382 CANJEM: a general population job exposure matrix based on past expert assessments of exposure to over 250 agents

ObjectivesTo create a general population job-exposure matrix (JEM) from a database of expert assessments performed during four community-based case-control studies of cancer (lung, breast, brain, and multisite) conducted in Montreal...

Risk factors for cholera transmission in Haiti during inter-peak periods: insights to improve current control strategies from two case-control studies

Two community-based density case-control studies were performed to assess risk factors for cholera transmission during inter-peak periods of the ongoing epidemic in two Haitian urban settings, Gonaives and Carrefour. The strongest associations were: close contact with cholera patients (sharing latrines, visiting cholera patients, helping someone with diarrhoea), eating food from street vendors and washing dishes with untreated water. Protective factors were: drinking chlorinated water, receiving prevention messages via television, church or training sessions, and high household socioeconomic level. These findings suggest that, in addition to contaminated water, factors related to direct and indirect inter-human contact play an important role in cholera transmission during inter-peak periods. In order to reduce cholera transmission in Haiti intensive preventive measures such as hygiene promotion and awareness campaigns should be implemented during inter-peak lulls, when prevention activities are typically scaled back.

Development of an Exposure Measurement Database on Five Lung Carcinogens (ExpoSYN) for Quantitative Retrospective Occupational Exposure Assessment

SYNERGY is a large pooled analysis of case-control studies on the joint effects of occupational carcinogens and smoking in the development of lung cancer. A quantitative job-exposure matrix (JEM) will be developed to assign exposures to five major lung carcinogens [asbestos, chromium, nickel, polycyclic aromatic hydrocarbons (PAH), and respirable crystalline silica (RCS)]. We assembled an exposure database, called ExpoSYN, to enable such a quantitative exposure assessment. Existing exposure databases were identified and European and Canadian research institutes were approached to identify pertinent exposure measurement data. Results of individual air measurements were entered anonymized according to a standardized protocol. The ExpoSYN database currently includes 356 551 measurements from 19 countries. In total, 140 666 personal and 215 885 stationary data points were available. Measurements were distributed over the five agents as follows: RCS (42%), asbestos (20%), chromium (16%), nickel (15%), and PAH (7%). The measurement data cover the time period from 1951 to present. However, only a small portion of measurements (1.4%) were performed prior to 1975. The major contributing countries for personal measurements were Germany (32%), UK (22%), France (14%), and Norway and Canada (both 11%). ExpoSYN is a unique occupational exposure database with measurements from 18 European countries and Canada covering a time period of >50 years. This database will be used to develop a country-, job-, and time period-specific quantitative JEM. This JEM will enable data-driven quantitative exposure assessment in a multinational pooled analysis of community-based lung cancer case-control studies.

Modelling of occupational respirable quartz exposure for quantitative exposure assessment in multinational community-based case-control studies

ObjectivesQuantitative exposure assessment in a multinational pooled-analysis of community-based lung cancer case-control studies can be reached via exposure modelling of occupational exposure measurements. We describe a modelling framework for respirable...

Exposure-response relation for occupational exposure to respirable quartz and lung cancer risk: performance of a quantitative vs a semi-quantitative job-exposure matrix

ObjectivesIn order to estimate the exposure-response relation of respirable quartz and lung cancer risk, we developed a quantitative time/job/region specific job-exposure matrix (JEM) based on statistical modelling of historical exposure...

Modelling of occupational respirable crystalline silica exposure for quantitative exposure assessment in community-based case-control studies

We describe an empirical model for exposure to respirable crystalline silica (RCS) to create a quantitative job-exposure matrix (JEM) for community-based studies. Personal measurements of exposure to RCS from Europe and Canada were obtained for exposure modelling. A mixed-effects model was elaborated, with region/country and job titles as random effect terms. The fixed effect terms included year of measurement, measurement strategy (representative or worst-case), sampling duration (minutes) and a priori exposure intensity rating for each job from an independently developed JEM (none, low, high). 23,640 personal RCS exposure measurements, covering a time period from 1976 to 2009, were available for modelling. The model indicated an overall downward time trend in RCS exposure levels of -6% per year. Exposure levels were higher in the UK and Canada, and lower in Northern Europe and Germany. Worst-case sampling was associated with higher reported exposure levels and an increase in sampling duration was associated with lower reported exposure levels. Highest predicted RCS exposure levels in the reference year (1998) were for chimney bricklayers (geometric mean 0.11 mg m(-3)), monument carvers and other stone cutters and carvers (0.10 mg m(-3)). The resulting model enables us to predict time-, job-, and region/country-specific exposure levels of RCS. These predictions will be used in the SYNERGY study, an ongoing pooled multinational community-based case-control study on lung cancer.

Epidemiologic Studies of Styrene and Cancer: A Review of the Literature

To review the epidemiologic literature on styrene and cancer. We reviewed studies of workers exposed to styrene in manufacturing and polymerization, in the reinforced plastics industry, and in styrene-butadiene rubber production. We also reviewed studies of workers monitored for styrene exposure, studies of environmental exposure, community-based case-control studies of lymphoma and leukemia, and studies of DNA adducts. Studies of workers in the reinforced plastics industry were considered more informative because of higher worker exposure and less confounding by other carcinogens. We found no consistent increased risk of any cancer among workers exposed to styrene. A study of reinforced plastic workers reported an association between average estimated styrene exposure and non-Hodgkin lymphoma (NHL, P = 0.05) but no trend with increasing duration of exposure. Other studies of styrene exposure and NHL found no increased risk. In two US studies of reinforced plastic workers, esophageal cancer mortality was increased, but these findings were generated in a background of multiple comparisons. Results for other cancers were unremarkable. The available epidemiologic evidence does not support a causal relationship between styrene exposure and any type of human cancer.

OccIDEAS: Retrospective Occupational Exposure Assessment in Community-Based Studies Made Easier

Assessing occupational exposure in retrospective community-based case-control studies is difficult as measured exposure data are very seldom available. The expert assessment method is considered the most accurate way to attribute exposure but it is a time consuming and expensive process and may be seen as subjective, nonreproducible, and nontransparent. In this paper, we describe these problems and outline our solutions as operationalized in a web-based software application (OccIDEAS). The novel aspects of OccIDEAS are combining all steps in the assessment into one software package; enmeshing the process of assessment into the development of questionnaires; selecting the exposure(s) of interest; specifying rules for exposure assignment; allowing manual or automatic assessments; ensuring that circumstances in which exposure is possible for an individual are highlighted for review; providing reports to ensure consistency of assessment. Development of this application has the potential to make high-quality occupational assessment more efficient and accessible for epidemiological studies.

Citrus fruit intake and stomach cancer risk: a quantitative systematic review

The purpose of this systematic review was to investigate the association between dietary intake of citrus fruits and gastric cancer risk. We searched electronic databases and the reference lists of publications on diet and stomach cancer studies until April 2007. All of the epidemiological studies that obtained individual data on dietary intake of citrus fruits and presented risk estimates of the association between intake of citrus fruits and risk of stomach cancer were identified and included in this review. Using general variance-based methods, study-specific odds ratio (OR)/ relative risk (RR) and associated confidence interval (CI)/ standard error (SE) for highest versus lowest intake of citrus fruits level were extracted from each article. Fourteen articles, including six hospital-based case-control studies, six community-based case-control studies, and two cohort studies, proved eligible. Overall summary OR using a fixed-effect model showed a 28% reduction in risk of stomach cancer associated with high intake of citrus fruits (summary OR = 0.72; 95% CI = 0.64-0.81; P value <0.0001); results were consistent across studies (I(2) = 0, where I(2) describes the percentage of total variation across studies because of heterogeneity rather than chance). Also, visual inspection of the results did not suggest a publication bias. Pooled results from observational studies support a protective effect of high citrus fruit intake in the risk of stomach cancer.

Issues When Modeling Benzene, Toluene, and Xylene Exposures Using a Literature Database

A database of benzene, toluene, and xylene measurements was compiled from an extensive literature review that contained information on several exposure determinants, including job type, operation, mechanism of release, process type, ventilation, temperature, distance from the source, quantity, and location. The database was used to develop statistical models for benzene, toluene, and xylene exposure as a function of operation and other workplace determinants. These models can be used to predict exposure levels for subjects enrolled in community-based case-control studies. This article presents the derived parameter estimates for specific operations and additional workplace exposure determinants and describes a number of statistical and data limitation issues that are inherent in determinants modeling of historical published data. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource(s): a PDF file of QQ plots and a Word file with references used in the benzene/toluene/xylene exposure database.]

An outbreak ofCryptosporidium hominisinfection at an Illinois recreational waterpark

Cryptosporidium has become increasingly recognized as a pathogen responsible for outbreaks of diarrhoeal illness in both immunocompetent and immunocompromised persons. In August 2001, an Illinois hospital reported a cryptosporidiosis cluster potentially linked to a local waterpark. There were 358 case-patients identified. We conducted community-based and waterpark-based case-control studies to examine potential sources of the outbreak. We collected stool specimens from ill persons and pool water samples for microscopy and molecular analysis. Laboratory-confirmed case-patients (n=77) were more likely to have attended the waterpark [odds ratio (OR) 16.0, 95% confidence interval (CI) 3.8-66.8], had pool water in the mouth (OR 6.0, 95% CI 1.3-26.8), and swallowed pool water (OR 4.5, 95% CI 1.5-13.3) than age-matched controls. Cryptosporidium was found in stool specimens and pool water samples. The chlorine resistance of oocysts, frequent swimming exposures, high bather densities, heavy usage by diaper-aged children, and increased recognition and reporting of outbreaks are likely to have contributed to the increasing trend in number of swimming pool-associated outbreaks of cryptosporidiosis. Recommendations for disease prevention include alteration of pool design to separate toddler pool filtration systems from other pools. Implementation of education programmes could reduce the risk of faecal contamination and disease transmission.

Critical literature review of determinants and levels of occupational benzene exposure for United States community-based case-control studies.

This article presents the results of an extensive literature review identifying the uses or occurrences of, and exposures to, benzene in a variety of industries for a community-based case-control study of childhood brain cancer in the United States and Canada. We focused on industries for which quantitative exposure data were identified in studies conducted in North America in the 1980s. Each industry was coded according to the 1987 Standard Industrial Classification (SIC) system. For each industry, information relevant to exposure assessment, including process descriptions, job titles, tasks, and work practices, was summarized when available. Estimates of probability and intensity of exposure, and our confidence in these estimates are presented. Arithmetic means (AMs), weighted for the number of measurements for each industry, were calculated based on measurement data from long-term (i.e., 60+ minutes) personal sampling; short-term or area samples were only used when no other data were available for a given industry. Industries for which no quantitative exposure levels were identified in the North American literature but for which information was found on benzene use are briefly described. Published exposure data indicate that workers in most industries in the 1980s experienced exposure levels below the current standard of 1 part per million (ppm), with a weighted AM of 0.33 ppm across all industries. Despite the longtime recognition of the hematological effects of benzene, little information was available on exposure levels and determinants for many industries with potential exposure. Nevertheless, this review may clarify some of the procedures involved in assessing occupational exposures in community-based studies and may aid in the interpretation of previous occupational studies that relied on job title or industry.

Exploring the relation of alcohol consumption to risk of breast cancer.

There are lingering questions regarding the relation between alcohol consumption and breast cancer risk in women. The authors performed a meta-analysis of epidemiologic studies carried out through 1999 to examine the dose-response relation and to assess whether effect estimates differed according to various study characteristics. Overall, there was a monotonic increase in the relative risk of breast cancer with alcohol consumption, but the magnitude of the effect was small; in comparison with nondrinkers, women averaging 12 g/day of alcohol consumption (approximately one typical drink) had a relative risk of 1.10 (95% confidence interval (CI): 1.06, 1.14). Estimates of relative risk were 7% greater in hospital-based case-control studies than in cohort studies or community-based case-control studies, 3% greater in studies published before 1990 than in studies published later, and 5% greater in studies conducted outside of the United States than in US studies. The findings of five US cohort studies published since 1990 yielded a relative risk of 1.06 (95% CI: 1.00, 1.11) for consumers of 12 g/day, as compared with nondrinkers. Cohort studies with less than 10 years of follow-up gave estimates 11% higher than cohort studies with longer follow-up periods. No meaningful difference was seen by menopausal status or type of beverage consumed.

Outbreaks of salmonellosis associated with eating uncooked tomatoes: implications for public health. The Investigation Team.

Laboratory-based surveillance of salmonella isolates serotyped at four state health departments (Illinois, Michigan, Minnesota and Wisconsin) led to the identification of multistate outbreaks of salmonella infections during 1990 (176 cases of S. javiana) and 1993 (100 cases of S. montevideo). Community-based case-control studies and product traceback implicated consumption of tomatoes from a single South Carolina tomato packer (Packer A) MOR 16.0; 95% CI2.1, 120.6; P < 0.0001 in 1990 and again in 1993 (MOR 5.7; 95 % CI 1.5, 21.9; P = 0.01) as the likely vehicle. Contamination likely occurred at the packing shed, where field grown tomatoes were dumped into a common water bath. These outbreaks represent part of a growing trend of large geographically dispersed outbreaks caused by sporadic or low-level contamination of widely distributed food items. Controlling contamination of agricultural commodities that are also ready-to-eat foods, particularly fruits and vegetables, presents a major challenge to industry, regulators and public health officials.

Assessment of occupational exposures in community-based case-control studies.

Assessing occupational exposures in community-based studies is a challenge for investigators because there are no standardized or validated approaches for collecting information regarding occupational history. The strengths and limitations of the methods available for assessing occupational exposures are reviewed. In community-based case-control studies, the prevalence of most chemical agents is low. The common sources of misclassification in these studies are addressed, as are strategies for dealing with misclassification bias. Methods to assess the presence and magnitude of differential reporting by cases and controls are outlined, together with analytic strategies to improve the classification of occupational exposures.

A critical review of epidemiology studies of trichloroethylene and perchloroethylene and risk of renal-cell cancer.

The epidemiology studies of trichloroethylene (TCE) and perchloroethylene (PCE) as they relate to risk of renal-cell cancer are critically reviewed. The studies fall into two basic groups: cohort studies of workers who use TCE or PCE and community-based case-control studies. Issues of bias, confounding, and chance are examined in relation to the studies. There is little evidence of an increased risk of renal-cell cancer and exposure to TCE or PCE. The few studies with elevations in risk suffer from important methodologic shortcomings. Although it is virtually impossible using epidemiology data to rule out conclusively a small increase in risk of renal-cell cancer, the totality of epidemiologic evidence clearly does not support a causal association with TCE or PCE. Future studies of these chemicals must include quantitative evidence of exposure and proper methodologic design, be large-scale in nature to detect small increases in risk, and provide a coherent interpretation of all epidemiology data on these solvents and risk of renal-cell cancer.