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Biomedical subjects

B Ritz

Publications and source records attributed to B Ritz.

At least 19 recordsLinked to original sources
PubMed2005

Estimated effects of disinfection by-products on birth weight in a population served by a single water utility.

Research has suggested that trihalomethane exposures during pregnancy might impair fetal growth. Most epidemiologic studies, however, relied on relatively crude exposure assessment methods and did not examine racial/ethnic subgroups. During 1999-2001, vital records data were obtained for a large, racially diverse population residing in 27 Massachusetts communities that received drinking water from a single public utility. The water system was monitored weekly for trihalomethanes and, system-wide, it maintained geographically stable total trihalomethane levels during the study period. The authors examined the effects of trimester-specific and pregnancy average exposures to total trihalomethane in drinking water on term low birth weight in all singleton births. A high average total trihalomethane exposure (> or = 70 microg/liter) during the second trimester increased the risk of term low birth weight (odds ratio = 1.50, 95% confidence interval (CI): 1.07, 2.10). The estimated risk increase for Caucasians during the second trimester was 37% (95% CI: 0.80, 2.36), while for all minority women combined (i.e., African Americans, Hispanics, and Asians) it was 60% (95% CI: 1.03, 2.47). The study data suggest that high levels (> or = 70 microg/liter) of trihalomethanes experienced during the second trimester and pregnancy overall may affect fetal growth.

Adult↗
PubMed2002

[Air permeable diaphyseal obturators: efficacity of femoral cementing and prevention of associated cardiovascular disorders].

PURPOSE OF THE STUDY: Insertion of cement plugs into the femoral shaft has become an essential part of total hip arthroplasty procedures. The goal is to achieve secure cementing of the femoral component, but the pressure induced can cause serious problems. The purpose of this study was to determine the effect of a flexible bioabsorbable cement restrictor with decompression valves on cementing efficacy and to determine the effect of inserting the restrictor then the cement plug into the femoral shaft on respiratory functions. MATERIAL AND METHODS: The restrictor was implanted in 108 patients undergoing first-intention total hip arthroplasty. The canal was prepared and calibrated before inserting the restrictor at a depth estimated at preoperative planning to be 10 to 20 mm below the tip of the femoral stem. The efficacy of the restrictor was assessed using radiographic criteria for the quality of the cement sheath and its position relative to the femoral stem. Oxygen saturation of arterial blood and end-expiration PCO2 were measured at first incision, at insertion of the restrictor, at insertion of the cement plug, and at insertion of the femoral stem. RESULTS: The relative position of the restrictor was measured on postoperative x-rays at less than 20 mm in 75% of the patients, at 20-40 mm in 13% and at more than 40 mm in 12%. No cement leakage through the restrictor was identified on postoperative x-rays. The quality of the cement sheath was satisfactory in 71% of the patients (77 procedures), fair in 20% (22 procedures) and poor in 8% (9 procedures). For a first group of patients operated on under spinal anesthesia and optional oxygen delivered with a face mask, there was no significant difference in arterial blood oxygen saturation before the procedure and during the four explored operative times. Conversely, in a second group of patients who had general anesthesia without oxygen enrichment of the initial oxygen-nitrogen protoxide gas mixture, arterial blood oxygen saturation during the four operative times was statistically different from the preoperative value. The same observation was made for end-expiratory PCO2. DISCUSSION: The retrictor's decompression valves did not allow cement leakage beyond the restrictor. The risk of restrictor migration after insertion and after the increased pressure due to cement plug insertion was not increased and was found to be less than rates reported in the literature. In the patients who had general anesthesia, blood gases showed a minimal, but significant, decrease during the operative times susceptible to induce increased intramedullary pressure. In patients who had a non-cemented acetabular insert, use of the pressure-valve cement restrictor appeared to stabilize these parameters.

Absorbable Implants↗
PubMed2001

[Study of blood pressure, hemodynamic, ventilatory and metabolic responses to isometric exercise performed during dynamic exercise in health subjects].

The object of this study was to study the blood pressure, haemodynamic, ventilatory and metabolic changes on isometric exercise during a dynamic effort in healthy subjects. Twelve healthy subjects underwent isometric exercise by manual prehension at 40% maximal capacity under these conditions: isolated (A), five minutes after the onset of rectangular dynamic exercise on a cycle at 60% of ventilatory threshold (B) and at the fourth minute of the recovery phase of dynamic exercise (C). The blood pressure, heart rate, stroke volume and cardiac index measured by Doppler echocardiography, systemic arterial resistances, respiratory flow and respiratory rate, were measured before and after each isometric exercise. The results showed blood pressure and heart rate to increase in a similar manner during isometric exercise under all conditions. The cardiac index increased by 29.5% +/- 8.3% (p < 0.01) under condition A and by 38.1% +/- 10% (p < 0.01) under conditions C but did not change significantly under conditions B. On the other hand, the systemic arterial resistances increased by 15.5% +/- 6.5% (p < 0.05) under conditions B, decreased by 8.8% +/- 3.9% (p < 0.05) under conditions C but did not change significantly under conditions A. The respiratory flow increased under all three conditions although the respiratory rate was only increased under conditions B. The authors conclude that, in healthy subjects, the increase in blood pressure during isometric and dynamic exercise is the result of an increase in systemic resistances whereas, during isometric exercise, it is flow-dependant.

Adult↗
PubMed2000

The effect of low-level blood lead on hematologic parameters in children.

A health survey of school children living in polluted regions of eastern Germany provided us with data necessary to examine the effects of lead on the blood system at levels below current standards for blood lead content. Data collected for 797 children, aged 5-14 years, with low blood lead levels (GM, 33.3 microg Pb/L; range, 7.5-239 microg Pb/L) allowed us to examine the relationship between blood lead content and hematological parameters. Using linear regression analyses and controlling for a number of potential confounding factors, we found that increasing blood lead levels by 10 microg/L were associated with a small increase in the number of red blood cells and in girls with reduced MCV and MCH. The reasons for our observation, especially the gender difference, are still uncertain. In conclusion the morphology and function of erythrocytes might be sensitive parameters of low dose lead toxicity.

Adolescent↗
PubMed2000

Gas cooking, respiratory health and white blood cell counts in children.

The use of gas stoves has been associated with respiratory symptoms of chronic airway inflammation and higher rates of respiratory infections. We used data from a 1992/93 survey of 2,198 East German school children (aged 5 to 14) to assess whether gas cooking increases respiratory symptoms and is associated with a chronic inflammatory process reflected by an increase in white blood cell (WBC) count in children who do not exhibit signs of an acute respiratory infection. We found increases for the respiratory symptoms 'cough without cold' [odds ratio (OR) = 1.68; 95% confidence interval (CI), 1.18-2.39], 'cough in the morning' (OR = 1.58; CI, 1.23-2.04) and 'cough during the day or at night' (OR = 1.42; CI, 1.13-1.78) in children living in homes with gas ranges, but lifetime prevalence of asthma, bronchitis, wheeze, and the prevalence of acute infections were not affected. Furthermore, we examined WBC levels in a subgroup of 1,134 children for whom blood samples were available and who did not suffer from an acute infection. We observed small increases in the risk of having WBC counts above the 75th or 90th percentile (8300 or 9800 cell counts per microliter) when children were exposed to gas cooking after adjustment for age, gender, and passive smoking (OR = 1.30; CI, 0.98-1.73, and OR = 1.38; CI, 0.91-2.10). The strongest effect estimates for chronic inflammation were found for those children likely to have been exposed at higher levels, that is when stoves had no fans, in smaller homes, and for children spending more time indoors.

Adolescent↗
PubMed2000

Parkinson's disease mortality and pesticide exposure in California 1984-1994.

BACKGROUND: In the last two decades reports from different countries emerged associating pesticide and herbicide use with Parkinson's disease (PD). California growers use approximately 250 million pounds of pesticides annually, about a quarter of all pesticides used in the US. METHODS: We employed a proportional odds mortality design to compare all cases of PD recorded as underlying (1984-1994) or associated causes (1984-1993) of death occurring in California with all deaths from ischaemic heart disease (ICD-9 410-414) during the same period. Based on pesticide use report data we classified California counties into several pesticide use categories. Agricultural census data allowed us to create measures of percentage of land per county treated with pesticides. Employing logistic regression models we estimated the effect of pesticide use controlling for age, gender, race, birthplace, year of deaths, and education. RESULTS: Mortality from PD as the underlying cause of death was higher in agricultural pesticide-use counties than in non-use counties. A dose response was observed for insecticide use per county land treated when using 1982 agricultural census data, but not for amounts of restricted pesticides used or length of residency in a country prior to death. CONCLUSIONS: Our data show an increased PD mortality in California counties using agricultural pesticides. Unless all of our measures of county pesticide use are surrogates for other risk factors more prevalent in pesticide use counties, it seems important to target this prevalent exposure in rural California in future studies that use improved case finding mechanisms and collect pesticide exposure data for individuals.

Aged↗
PubMed2000

Effect of air pollution on preterm birth among children born in Southern California between 1989 and 1993.

We evaluated the effect of air pollution exposure during pregnancy on the occurrence of preterm birth in a cohort of 97,518 neonates born in Southern California. We used measurements of carbon monoxide (CO), nitrogen dioxide, ozone, and particulate matter less than 10 microm (PM10) collected at 17 air-quality-monitoring stations to create average exposure estimates for periods of pregnancy. We calculated crude and adjusted risk ratios (RRs) for premature birth by period-specific ambient pollution levels. We observed a 20% increase in preterm birth per 50-microg increase in ambient PM10 levels averaged over 6 weeks before birth [RRcrude = 1.20; 95% confidence interval (CI) = 1.09-1.33] and a 16% increase when averaging over the first month of pregnancy (RRcrude = 1.16; 95% CI = 1.06-1.26). PM10 effects showed no regional pattern. CO exposure 6 weeks before birth consistently exhibited an effect only for the inland regions (RRcrude = 1.13; 95% CI = 1.08-1.18 per 3 parts per million), and during the first month of pregnancy, the effect was weak for all stations (RRcrude = 1.04; 95% CI = 1.01-1.09 per 3 parts per million). Exposure to increased levels of ambient PM10 and possibly CO during pregnancy may contribute to the occurrence of preterm births in Southern California.

Air Pollutants↗
PubMed2000

The effects of internal radiation exposure on cancer mortality in nuclear workers at Rocketdyne/Atomics International.

We examined the effects of chronic exposure to radionuclides, primarily uranium and mixed-fission products, on cancer mortality in a retrospective cohort study of workers enrolled in the radiation-monitoring program of a nuclear research and development facility. Between 1950 and 1994, 2,297 workers were monitored for internal radiation exposures, and 441 workers died, 134 (30.4%) of them from cancer as the underlying cause. We calculated internal lung-dose estimates based on urinalysis and whole-body and lung counts reported for individual workers. We examined cancer mortality of workers exposed at different cumulative lung-dose levels using complete risk-set analysis for cohort data, adjusting for age, pay type, time since first radiation monitored, and external radiation. In addition, we examined the potential for confounding due to chemical exposures and smoking, explored whether external radiation exposure modifies the effects of internal exposure, and estimated effects after excluding exposures likely to have been unrelated to disease onset. Dose-response relations were observed for death from hemato- and lymphopoietic cancers and from upper aerodigestive tract cancers, adjusting for age, time since first monitored, pay type, and external (gamma) radiation dose. No association was found for other cancers, including cancers of the lung. Despite the small number of exposed deaths from specific cancer types and possible bias due to measurement error and confounding, the positive findings and strong dose-response gradients observed suggest carcinogenic effects of internal radiation to the upper aerodigestive tract and the blood and lymph system in this occupational cohort. However, causal inferences require replication of our results in other populations or confirmation with an extended follow-up of this cohort.

California↗
PubMed1999

Effects of exposure to external ionizing radiation on cancer mortality in nuclear workers monitored for radiation at Rocketdyne/Atomics International.

BACKGROUND AND METHODS: A retrospective cohort study was conducted to estimate the effects of low-level exposure to external (penetrating) radiation on cancer mortality among 4,563 workers monitored for external radiation between 1950 and 1993 at a nuclear research and production facility in Southern California. RESULTS: Of the 875 deaths that occurred before 1995, 258 were due to cancer as the underlying cause. External comparisons of male subjects with the U.S. white male population indicated that the workers had lower rates of dying from all causes and all cancers, but a higher rate of dying from leukemia. Internal comparisons of workers exposed at different dose levels, using risk-set analyses with adjustment for confounders, demonstrated an increased mortality rate in workers exposed to 200 mSv for hemato- and lymphopoietic cancers and for lung cancer. Mortality rates for total cancers and "radiosensitive" solid cancers increased monotonically with cumulative radiation dose, but no trends were observed for "nonradiosensitive" cancers. CONCLUSIONS: Despite possible residual confounding and low precision for estimating effects on specific cancers, these findings indicate that chronic, low-level radiation exposure may have more generalized carcinogenic effects than have been observed in most previous investigations. Such effects may have become evident as a result of the relatively long follow-up period in the present study.

Adult↗
PubMed1999

Cancer mortality among workers exposed to chemicals during uranium processing.

Data provided by the Comprehensive Epidemiology Data Resource allowed us to study patterns of cancer mortality as experienced by 3814 uranium-processing workers employed at the Fernald Feed Materials Production Center in Fernald, Ohio. Using risk-set analyses for cohorts, we estimated the effects of exposure to trichloroethylene, cutting fluids, and kerosene on cancer mortality. Our results suggest that workers who were exposed to trichloroethylene experienced an increase in mortality from cancers of the liver. Cutting-fluid exposure was found to be strongly associated with laryngeal cancers and, furthermore, with brain, hemato- and lymphopoietic system, bladder, and kidney cancer mortality. Kerosene exposure increased the rate of death from several digestive-tract cancers (esophageal, stomach, pancreatic, colon, and rectal cancers) and from prostate cancer. Effect estimates for these cancers increased with duration and level of exposure and were stronger when exposure was lagged.

Adult↗
PubMed1999

Chemical exposures of rocket-engine test-stand personnel and cancer mortality in a cohort of aerospace workers.

We conducted a retrospective cohort study of 6107 aerospace workers to examine whether exposure to chemicals--primarily hydrazine fuels--during rocket-engine fueling and testing affects cancer mortality. When conditional logistic regression analysis was applied and adjusted for confounding variables, the estimated rate ratio for lung cancer mortality, comparing exposed to unexposed workers from the same facility, ranged from 1.68 (95% confidence interval, 1.12 to 2.52) to 2.10 (95% confidence interval, 1.36 to 3.25), depending on job-duration threshold (6 or 24 months) and lag (0 to 15 years). Similar results were obtained for hemato- and lymphopoietic cancer and for bladder and kidney cancer mortality, but estimates for these cancers were imprecise. We concluded that occupational exposure to hydrazine or other chemicals associated with rocket-engine testing jobs increased the risk of dying from lung cancer, and possibly other cancers, in this population of aerospace workers; however, our results need to be replicated in other populations.

Carcinogens↗
PubMed1999

The effect of ambient carbon monoxide on low birth weight among children born in southern California between 1989 and 1993.

We evaluated the effect of carbon monoxide (CO) exposures during the last trimester of pregnancy on the frequency of low birth weight among neonates born 1989-1993 to women living in the Los Angeles, California, area. Using birth certificate data for that period, we assembled a retrospective cohort of infants whose mothers resided within 2 miles of 1 of 18 CO monitoring stations. Based on the gestational age and birth date of each child, we estimated last-trimester exposure by averaging the corresponding 3 months of daily CO concentrations registered at the monitoring station closest to the mother's residence (determined from the birth certificate). Where data were available (at 6 stations), we also averaged measurements taken daily for nitrogen dioxide and ozone and those taken at 6-day intervals for particulate matter [less than/equal to]10 microm (PM10) to approximate last-trimester exposures to other pollutants. Overall, the study cohort consisted of 125,573 singleton children, excluding infants born before 37 or after 44 weeks of gestation, those weighing below 1,000 or above 5,500 g at birth, those for whom fewer than 10 days of CO measurements were available during the last trimester, and those whose mothers suffered from hypertension, diabetes, or uterine bleeding during pregnancy. Within the cohort, 2,813 (2.2%) were low in birth weight (between 1,000 and 2,499 g). Exposure to higher levels of ambient CO (>5.5 ppm 3-month average) during the last trimester was associated with a significantly increased risk for low birth weight [odds ratio (OR) = 1.22; 95% confidence interval (CI), 1.03-1.44] after adjustment for potential confounders, including commuting habits in the monitoring area, sex of the child, level of prenatal care, and age, ethnicity, and education of the mother.

Adolescent↗
PubMed1999

Respiratory diseases and allergies in two polluted areas in East Germany.

This cross-sectional epidemiological study collected health data for 2,470 school children between 5 and 14 years of age (89% of eligible children) who had lived most of their lives in either one of two counties strongly impacted by industrial pollution (Bitterfeld and Hettstedt) or in a neighboring county without any sources of industrial pollution (Zerbst). The objective of the study was to examine whether regional differences--with respect to the occurrence of childhood respiratory diseases and symptoms or allergies--exist and, if such differences are found, whether they persist when we adjust for the effects of known risk factors such as medical and sociodemographic factors or factors related to the indoor environment. Controlling for medical, sociodemographic, and indoor factors, according to parental reports, children residing in Hettstedt have about a 50% increased lifetime prevalence for physician-diagnosed allergies, eczema, and bronchitis compared to children from Zerbst and about twice the number of respiratory symptoms such as wheeze, shortness of breath, and cough without cold. Sensitization to common aeroallergens according to skin prick tests [odds ratio (OR) = 1.38; 95% confidence interval (CI), 1.02-1.86] and specific IgE levels (OR = 1.75; CI, 1.31-2.33) was more common for children from Hettstedt than children from the nonpolluted county. Bitterfeld children, on the other hand, more often received a diagnosis of asthma and eczema than children residing in Zerbst and also showed slightly increased sensitization rates. In conclusion, industrial pollution related to mining and smelting operations in the county of Hettstedt were associated with a higher lifetime prevalence of respiratory disorders and an increased rate of allergic sensitization in children between the ages of 5 and 14 years. Further studies are needed to determine what role the high dust content of heavy metals plays in Hettstedt.

Adult↗
PubMed1999

Age at exposure modifies the effects of low-level ionizing radiation on cancer mortality in an occupational cohort.

In a cohort of 4,563 nuclear workers followed retrospectively from 1950 to 1994, we found that age at exposure modified the effects of external radiation dose on cancer mortality. Analyses involved application of conditional logistic regression to risk sets of age- and calendar time-matched cancer deaths, with covariates treated as time dependent and with cumulative radiation doses divided according to the age intervals in which exposure occurred. After adjustment for confounding factors, we found that workers exposed to external radiation after the age of 50 years experienced exposure-related elevations in mortality from cancer at any site [rate ratio (RR) = 1.98; 95% confidence interval (CI) = 0.63-6.26], radiosensitive solid cancer (RR = 3.29; 95% CI = 1.10-9.89), and lung cancer (RR = 3.89; 95% CI = 1.23-12.3) substantially greater (1.6- to 3.5-fold greater) than were seen in coworkers exposed at all earlier ages. In contrast, all of the radiation doses contributing to mortality from cancers of the blood and lymph system were received before age 50 (for age <50, RR = 2.73 and 95% CI = 1.46-5.10; for age > or =50, RR = 0.24 and 95% CI = 0.00-687). Our results for cancer of any site are consistent with the results of previous studies examining the effects of exposure age in nuclear workers. Thus, effects of low-level radiation doses may depend on exposure age, and furthermore, patterns of effect modification by age may differ by type of cancer.

Age Factors↗
PubMed1999

Radiation exposure and cancer mortality in uranium processing workers.

Data from the Comprehensive Epidemiology Data Resource (CEDR) allowed me to study patterns of cancer mortality in a cohort of 4,014 uranium-processing workers. Employing risk-set analysis for cohort data, I estimated the effects of external (gamma) and internal (alpha) radiation on cancer mortality. My results indicate that Fernald workers exposed to ionizing radiation experienced an increase in mortality from total cancer (per 100 mSv external dose rate ratio (RR) = 1.92; 95% confidence interval (CI) = 1.11-3.32), radiosensitive solid cancer (RR = 2.00; 95% CI = 1.02-3.94), and lung cancer (RR = 2.77; 95% CI = 1.29-5.95). Effects were strongest when exposure had occurred at older ages (>40 years). In addition, I observed an increase in lung-cancer mortality for workers exposed to > or =200 mSv of internal (alpha) radiation (RR = 1.92; 95% CI = 0.53-6.96). Furthermore, my results demonstrate the importance of a long follow-up time when studying solid cancers, the potential for bias due to worker selection associated with concomitant chemical exposures, problems of exposure measurement, confounding, and effect modification due to age at exposure. Owing to lack of data, a previous pooled analysis of uranium-processing workers could only partially address these issues.

Adult↗
PubMed1998

Chronicle of a Kenyan mission.

The mission of the Christ United Methodist Church of the Deaf has been to provide a cross-cultural experience with deaf and hearing impaired persons from other countries. In this way, deaf members from the United States not only give of themselves in ministry and in service, but also share and gain invaluable insight into the lives of the deaf all over the world.

Baltimore↗