Chiu-Kit Tse

Cigarette smoking and semen quality.

OBJECTIVE To determine whether cotinine levels provide stronger evidence for an association between smoking and semen quality than the number of cigarettes smoked per day or years smoked controlling for potential confounders and effect modifiers. DESIGN Cross-sectional study. SETTING Male volunteers at the Reproductive Endocrinology-Fertility Laboratory. PARTICIPANTS Eighty-eight men (ages 18 to 35 years) provided a semen, urine, and blood specimen and completed a self-administered questionnaire concerning smoking and demographic information as well as caffeine and alcohol consumption. Urine, blood, and semen cotinine levels were analyzed via RIA. MAIN OUTCOME MEASURE Standard clinical semen analysis. RESULTS Number of cigarettes smoked per day, years smoked, and log-transformed cotinine levels were associated negatively with semen quality (density, total count, and motility). The association was evident among men age > or = 22 years. For example, the correlation coefficient for the overall association between logged urine cotinine and logged sperm density was -0.23; those stratified by age were 0. 13 (age < 22 years) and - 0. 39 (age > or = 22 years). Potential confounders included in regression models did not diminish the associations. CONCLUSIONS Smoking is associated with lowered semen quality.

Electrical Occupations and Neurodegenerative Disease: Analysis of U.S. Mortality Data

Investigators have hypothesized that occupations involving electric and magnetic field exposure are associated with a variety of health problems, including neurological disease. The authors conducted a case-control study, and they used U.S. death certificates with occupational coding to compare male cases of Alzheimers disease (n = 256), Parkinsons disease (n = 168), and amyotrophic lateral sclerosis (n = 114) with controls matched for age and calendar time. The authors selected controls in a 3:1 ratio to cases from persons who died of causes other than leukemia, brain cancer, and breast cancer. Overall associations with electrical occupations were modest (i.e., adjusted odds ratios of 1.2, 1.1, and 1.3 for Alzheimers disease, Parkinsons disease, and amyotrophic lateral sclerosis, respectively). Individual electrical occupations were associated more strongly with disease than overall electrical occupations, particularly amyotrophic lateral sclerosis, for which relative risks ranged from 2 to 5 across several job categories. The largest associations with all three diseases occurred for power plant operators.

Polychlorinated biphenyls, cytochrome P450 1A1 (CYP1A1) polymorphisms, and breast cancer risk among African American women and white women in North Carolina: a population-based case-control study

IntroductionEpidemiologic studies have not shown a strong relationship between blood levels of polychlorinated biphenyls (PCBs) and breast cancer risk. However, two recent studies showed a stronger association among postmenopausal white women with the inducible M2 polymorphism in the cytochrome P450 1A1 (CYP1A1) gene.MethodsIn a population-based case-control study, we evaluated breast cancer risk in relation to PCBs and the CYP1A1 polymorphisms M1 (also known as CYP1A1*2A), M2 (CYP1A1*2C), M3 (CYP1A1*3), and M4 (CYP1A1*4). The study population consisted of 612 patients (242 African American, 370 white) and 599 controls (242 African American, 357 white).ResultsThere was no evidence of strong joint effects between CYP1A1 M1-containing genotypes and total PCBs in African American or white women. Statistically significant multiplicative interactions were observed between CYP1A1 M2-containing genotypes and elevated plasma total PCBs among white women (P value for likelihood ratio test = 0.02). Multiplicative interactions were also observed between CYP1A1 M3-containing genotypes and elevated total PCBs among African American women (P value for likelihood ratio test = 0.10).ConclusionsOur results confirm previous reports that CYP1A1 M2-containing genotypes modify the association between PCB exposure and risk of breast cancer. We present additional evidence suggesting that CYP1A1 M3-containing genotypes modify the effects of PCB exposure among African American women. Additional studies are warranted, and meta-analyses combining results across studies will be needed to generate more precise estimates of the joint effects of PCBs and CYP1A1 genotypes.

Cigarette smoking, cytochrome P4501A1 polymorphisms, and breast cancer among African-American and white women

IntroductionPrevious epidemiologic studies suggest that women with variant cytochrome P4501A1 (CYP1A1) genotypes who smoke cigarettes are at increased risk for breast cancer.MethodsWe evaluated the association of breast cancer with CYP1A1 polymorphisms and cigarette smoking in a population-based, case–control study of invasive breast cancer in North Carolina. The study population consisted of 688 cases (271 African Americans and 417 whites) and 702 controls (285 African Americans and 417 whites). Four polymorphisms in CYP1A1 were genotyped using PCR/restriction fragment length polymorphism analysis: M1 (also known as CYP1A1*2A), M2 (CYP1A1*2C), M3 (CYP1A1*3), and M4 (CYP1A1*4)ResultsNo associations were observed for CYP1A1 variant alleles and breast cancer, ignoring smoking. Among women who smoked for longer than 20 years, a modest positive association was found among women with one or more M1 alleles (odds ratio [OR] = 2.1, 95% confidence interval [CI] = 1.2–3.5) but not among women with non-M1 alleles (OR = 1.2, 95% CI = 0.9–1.6). Odds ratios for smoking longer than 20 years were higher among African-American women with one or more M3 alleles (OR = 2.5, 95% CI = 0.9–7.1) compared with women with non-M3 alleles (OR = 1.3, 95% CI = 0.8–2.2). ORs for smoking in white women did not differ appreciably based upon M2 or M4 genotypes.ConclusionsCigarette smoking increases breast cancer risk in women with CYP1A1 M1 variant genotypes and in African-American women with CYP1A1 M3 variant genotypes, but the modifying effects of the CYP1A1 genotype are quite weak.

Determinants of Breast Cancer Treatment Delay Differ for African American and White Women

Background: Timeliness of care may contribute to racial disparities in breast cancer mortality. African American women experience greater treatment delay than White women in most, but not all studies. Understanding these disparities is challenging as many studies lack patient-reported data and use administrative data sources that collect limited types of information. We used interview and medical record data from the Carolina Breast Cancer Study (CBCS) to identify determinants of delay and assess whether disparities exist between White and African American women (n = 601). Methods: The CBCS is a population-based study of North Carolina women. We investigated the association of demographic and socioeconomic characteristics, healthcare access, clinical factors, and measures of emotional and functional well-being with treatment delay. The association of race and selected characteristics with delays of more than 30 days was assessed using logistic regression. Results: Household size, losing a job due to ones diagnosis, and immediate reconstruction were associated with delay in the overall population and among White women. Immediate reconstruction and treatment type were associated with delay among African American women. Racial disparities in treatment delay were not evident in the overall population. In the adjusted models, African American women experienced greater delay than White women for younger age groups: OR, 3.34; 95% confidence interval (CI), 1.07–10.38 for ages 20 to 39 years, and OR, 3.40; 95% CI, 1.76–6.54 for ages 40 to 49 years. Conclusions: Determinants of treatment delay vary by race. Racial disparities in treatment delay exist among women younger than 50 years. Impact: Specific populations need to be targeted when identifying and addressing determinants of treatment delay. Cancer Epidemiol Biomarkers Prev; 22(7); 1227–38. ©2013 AACR.

Male and female occupation in relation to miscarriage and preterm delivery in central North Carolina

PURPOSE This study was undertaken to evaluate the role of parental occupation in miscarriage and preterm delivery. Previous studies raise the possibility that both male and female exposures could affect pregnancy. METHODS Data from a population-based study of miscarriage and preterm delivery in central North Carolina were used to examine potential associations with male and female occupation. Medically treated miscarriage cases (n = 418), preterm delivery cases identified through hospital record review (n = 582), and term, normal birth weight controls (n = 787) were sought for telephone interview. The interview included information on jobs the woman held before and during the pregnancy, reports of her partners job around the time of pregnancy, and information on potential confounding factors. RESULTS Female employment overall, or in specific jobs, around the time of conception or early pregnancy was not associated with the risk of miscarriage, whereas working during pregnancy, especially in the seventh month, was inversely associated with risk of preterm delivery. Male employment in several industrial occupations was weakly associated with miscarriage (adjusted odds ratios (OR) of 1.6 to 1.8), and somewhat more strongly associated with preterm delivery, particularly for chemists and sheet metal workers (adjusted OR over 3). Restriction to married men strengthened the associations. CONCLUSIONS Our results are limited by nonresponse, imprecision, incomplete identification of miscarriages, and lack of detailed occupational exposure information. Nonetheless, we found greater support for further examination of male compared to female jobs in relation to pregnancy outcome.

Reproducibility of Reported Farming Activities and Pesticide Use among Breast Cancer Cases and Controls: A Comparison of Two Modes of Data Collection

PURPOSE Farming is associated with exposure to many potential hazards including pesticides and other agents, but the quality of self-reported data on farm exposures has not been well studied. METHODS The reproducibility of self-reported farming history was evaluated among women in a population-based, case-control study of breast cancer in North Carolina. Thirty cases and 31 controls were randomly re-interviewed by telephone an average of 13.8 months after the initial interview. The initial interview was based on a farm-by-farm questionnaire, while the repeat interview was based on a shorter ever/never questionnaire. Agreement was estimated using proportions in exact agreement, kappa (kappa), and intraclass correlation coefficients (ICC). RESULTS In general, group prevalences and means were higher on re-interview. Kappa estimates ranged from 0.15 to 0.84 among cases, and 0.26 to 0.87 among controls, with most estimates falling between 0.5 and 0.8. Moderate to almost perfect agreement (kappa) was observed for questions on crop work (0.47-0.70), crop type (0.56-0.82), pesticide application to tobacco (0.77), and farm residence (0.84). ICC estimates for continuous variables showed fair to substantial agreement (0.30 to 0.69 among cases, 0.38 to 0.69 among controls). Older cases, less educated cases, cases who lived on more than one farm, and cases with longer time intervals between interviews gave lower total agreement than similar groups of controls. CONCLUSIONS Agreement estimates in this study are similar to those for other types of exposure information typically collected in epidemiologic studies. Nevertheless, a farm-by-farm method of exposure assessment may be preferable to an ever/never determination.

Male and female employment in the textile industry in relation to miscarriage and preterm delivery

To address potential reproductive hazards in textile manufacturing, we conducted a community-based case-control study in central North Carolina. Miscarriage cases were identified from medical records (280 interviewed cases): preterm delivery cases and term, normal birth weight controls (454 and 605, respectively) were identified from area hospitals. Exposures were based on job title, an interview concerning textile-related exposures, expert imputation of exposure based on job titles and interviews, and self-reported exposures by women. Relative to women and men working in nonhazardous occupations, workers in the textile industry were not at increased risk of miscarriage or preterm delivery, with the possible exception of preterm delivery among women and men employed in sectors other than knitting and yarn mills and men employed in yarn mills. Inferred exposures to specific agents were also not associated with adverse pregnancy outcome. Subject to uncertainty in exposure assessment and nonresponse, these data indicate an absence of adverse effects of the textile workplace environment on these pregnancy outcomes.