Electrokinetic dewatering of Turkish glass sand plant tailings

In this study, the dewatering of glass sand plant tailings from Mersin, Turkey was investigated using an electrokinetic technique. The particle size (d(80)) of the solid waste material tested was less than 0.020 mm and consisted mainly of silica, orthoclase, alumina, potassium and iron oxides. In current plant practice, Larox high-pressure filters are used to produce a filter cake containing 22-25% moisture. As an alternative, a laboratory-scale dewatering pond using an electrokinetic technique was designed and a final product (cake) containing 34% moisture was obtained after 24h treatment using 14.6 V direct current applied for 40 min. When the treatment continued up to 48 h, a firm-to-hard cake was produced.

Maintenance treatment with interferon for advanced ovarian cancer: results of the Northern and Yorkshire gynaecology group randomised phase III study

A randomised phase III trial was conducted to assess the role of interferon-alpha (INFalpha) 2a as maintenance therapy following surgery and/or chemotherapy in patients with epithelial ovarian carcinoma. Patients were randomised following initial surgery/chemotherapy to interferon-alpha 2a as 4.5 mega-units subcutaneously 3 days per week or to no further treatment. A total of 300 patients were randomised within the study between February 1990 and July 1997. No benefit for interferon maintenance was seen in terms of either overall or clinical event-free survival. We conclude that INF-alpha is not effective as a maintenance therapy in the management of women with ovarian cancer. The need for novel therapeutics or strategies to prevent the almost inevitable relapse of patients despite increasingly effective surgery and chemotherapy remains.

Diet, GSTM1 and GSTT1 and head and neck cancer

A decreased incidence of squamous cell carcinoma of the head and neck (SCCHN) associated with fruit and vegetable intake may act through chemopreventive compounds, which may be more available to persons homozygous for the deletion genotypes of the glutathione S-transferase (GST). We evaluated interactions between fruits and vegetables and GSTM1 and GSTT1 on incidence of SCCHN using data from a case-control study of 149 cases and 180 age- and gender-matched controls. After adjustment for age, gender, race, tobacco and alcohol use, weekly consumption of four or more servings of raw vegetables was inversely associated with SCCHN [odds ratio (OR) = 0.66, 95% confidence intervals (CI) 0.30-1.3]. Contrary to expectation, relatively high intake of cooked vegetables (14 or more weekly servings) and legumes (two or more weekly servings) were associated with increased incidence (OR = 2.5, 95% CI 1.1-6.0; OR = 2.5, 95% CI 1.2-5.2, respectively). In general, our results did not suggest a clear or consistent pattern of modification by GST genotypes of the association between foods and SCCHN. For example, eating cruciferous vegetables, foods of a priori interest, and having the GSTM1-deletion genotype was not associated with the expected reduction in incidence compared with abstaining from cruciferous vegetable intake and having the GSTM1-present genotype. Among non-consumers of cruciferous vegetables, the GSTM1-deletion genotype was inversely associated with SCCHN (OR = 0.55, 95% CI 0.07-4.2). Raw vegetables were associated with a reduction in incidence only among persons with the GSTM1-deletion genotype (OR = 0.69, 95% CI 0.29-1.6), whereas either factor alone had a null association. Future research of GST-diet interactions and SCCHN would benefit from larger, population-based studies.

Sexual assault among North Carolina women: prevalence and health risk factors

STUDY OBJECTIVE

Sexual assault is traumatic at the time it occurs, but it also may have longlasting negative effects on physical health. Much of the research linking specific health problems to sexual assault victimization has used samples from special populations. The goals of this study are to estimate the prevalence of sexual assault in a representative sample of women in North Carolina and examine sexual assault in relation to specific health risk factors for leading causes of morbidity and mortality in women.

DESIGN

The North Carolina Behavioral Risk Factor Surveillance System (BRFSS) is a household telephone survey of non-institutionalised adults, 18 years of age and older, conducted by random digit dialling.

SETTING

This investigation focuses on the study participants in the 1997 survey.

PARTICIPANTS

The sample includes 2109 women who responded to the sexual assault questions in the 1997 North Carolina BRFSS interview.

MAIN RESULTS

The lifetime prevalence of sexual assault was 19% (95% CI 17% to 20%), of which 73% of victims experienced or were threatened with forced sexual intercourse. Sexual assault victims, particularly victims of forced intercourse or the threat thereof, were more likely to perceive their general health as being fair or poor (OR=2.3, 95% CI 1.5 to 3.4) and were more likely to have suffered poor physical and mental health in the past month (poor physical health, OR=2.1, 95% CI 1.6 to 2.8; poor mental health, OR= 2.6, 95% CI 1.9 to 3.5). After controlling for sociodemographic factors and health care coverage, victims of forced intercourse or the threat thereof were more likely to smoke cigarettes (OR=2.0, 95% CI 1.4 to 2.8), to have hypertension (OR=1.5, 95% CI 1.1 to 2.2), to have high cholesterol (OR=1.7, 95% CI 1.2 to 2.5), and to be obese (OR=1.7, 95% CI 1.3 to 2.4).

CONCLUSIONS

This study shows associations between sexual victimization and health risk factors in a non-clinical statewide population of women. Future research should determine whether clinically screening for and identifying a history of sexual victimization among women seen in a variety of health care settings leads to the initiation of effective interventions that help women successfully cope with these violent experiences. There is also a need for further research to investigate the temporal sequence of assaults and subsequent health outcomes by assessing physical health status before and after victimization.

Quadriceps moment arm and quadriceps forces after total knee arthroplasty

Knee prosthetic designs that increase quadriceps moment arm can reduce quadriceps tension and patellofemoral compressive forces. Six knees from cadavers were tested on the Oxford knee rig, which simulates closed chain knee extension under load. Three conditions were tested sequentially for each knee: Normal, Control (implanted with the Osteonics 7000 knee design), and Scorpio (implanted with the Osteonics Scorpio design). The center of flexion-extension of the Scorpio design was 10 mm posterior to that of Control that served to lengthen the quadriceps moment arm. An electromagnetic tracking system measured dynamic knee kinematics, and a uniaxial load cell measured quadriceps tension. The Scorpio design reduced quadriceps tension when compared with the Normal or Control knee ranging from 5% to 20%. This was statistically significant at flexion angles greater than 50 degrees. In three knees, the patellar component was instrumented with a triaxial load cell that measured patellofemoral forces. Patellofemoral forces were lower with the Scorpio design compared with the Control. Increasing quadriceps lever arm reduces quadriceps forces and can facilitate activities of daily living and enhance patient rehabilitation. Reduced quadriceps forces may result in reduced patellofemoral forces that can have a beneficial effect on anterior knee pain, patellar component wear, and loosening.

Does tea affect cardiovascular disease? A meta-analysis

This meta-analysis of tea consumption in relation to stroke, myocardial infarction, and all coronary heart disease is based on 10 cohort studies and seven case-control studies. The study-specific effect estimates for stroke and coronary heart disease were too heterogeneous to be summarized (homogeneity p < 0.02 for stroke, p < 0.001 for coronary heart disease). Only the relative risk estimates for myocardial infarction (seven studies) appeared reasonably homogeneous (homogeneity p = 0.20). The incidence rate of myocardial infarction is estimated to decrease by 11% with an increase in tea consumption of 3 cups per day (fixed-effects relative risk estimate = 0.89, 95% confidence interval: 0.79, 1.01) (1 cup = 237 ml). However, evidence of bias toward preferential publication of smaller studies that suggest protective effects urges caution in interpreting this result. The geographic region where the studies were conducted appeared to explain much of the heterogeneity among coronary heart disease, myocardial infarction, and probably stroke results. With increasing tea consumption, the risk increased for coronary heart disease in the United Kingdom and for stroke in Australia, whereas the risk decreased in other regions, particularly in continental Europe.

Parental occupational exposures to electromagnetic fields and radiation and the incidence of neuroblastoma in offspring

We examined parental occupational exposures to electromagnetic fields and radiation and the incidence of neuroblastoma in offspring. Cases were 538 children diagnosed with neuroblastoma between 1992 and 1994 in the United States or Canada. Age-matched controls were selected by random-digit dialing. Occupational exposures to electrical equipment and radiation sources were classified by an industrial hygienist, and average exposures to extremely low frequency magnetic fields were estimated using a job exposure matrix. Maternal exposure to a broad grouping of sources that produce radiofrequency radiation was associated with an increased incidence of neuroblastoma (odds ratio = 2.8; 95% confidence interval = 0.9-8.7). Paternal exposure to battery-powered forklifts was positively associated with neuroblastoma (odds ratio = 1.6; 95% confidence interval = 0.8-3.2), as were some types of equipment that emit radiofrequency radiation (odds ratios congruent with 2.0); however, the broad groupings of sources that produce ELF fields, radiofrequency radiation, or ionizing radiation were not associated with neuroblastoma. Paternal average extremely low frequency magnetic field exposure >0.4 microTesla was weakly associated with neuroblastoma (odds ratio = 1.6; 95% confidence interval = 0.9-2.8), whereas maternal exposure was not. Overall, there was scant supportive evidence of strong associations between parental exposures in electromagnetic spectrum and neuroblastoma in offspring.

Parental occupational exposures to chemicals and incidence of neuroblastoma in offspring

To evaluate the effects of parental occupational chemical exposures on incidence of neuroblastoma in offspring, the authors conducted a multicenter case-control study, using detailed exposure information that allowed examination of specific chemicals. Cases were 538 children aged 19 years who were newly diagnosed with confirmed neuroblastoma in 1992-1994 and were registered at any of 139 participating hospitals in the United States and Canada. One age-matched control for each of 504 cases was selected through random digit dialing. Self-reported exposures were reviewed by an industrial hygienist, and improbable exposures were reclassified. Effect estimates were calculated using unconditional logistic regression, adjusting for child's age and maternal demographic factors. Maternal exposures to most chemicals were not associated with neuroblastoma. Paternal exposures to hydrocarbons such as diesel fuel (odds ratio (OR) = 1.5; 95% confidence interval (CI): 0.8, 2.6), lacquer thinner (OR = 3.5; 95% CI: 1.6, 7.8), and turpentine (OR = 10.4; 95% CI: 2.4, 44.8) were associated with an increased incidence of neuroblastoma, as were exposures to wood dust (OR = 1.5; 95% CI: 0.8, 2.8) and solders (OR = 2.6; 95% CI: 0.9, 7.1). The detailed exposure information available in this study has provided additional clues about the role of parental occupation as a risk factor for neuroblastoma.

Do studies of wire code and childhood leukemia point towards or away from magnetic fields as the causal agent?

A long-standing point of controversy in the epidemiologic literature concerns the meaning of a wire code-childhood leukemia association for assessing the role of magnetic field exposure. Six studies of wire codes and childhood leukemia in North America were examined, three of which reported positive associations and all of which found some relation between wire codes and measured magnetic fields. Supporting magnetic fields as the basis for the wire code associations are the correspondence between those wire code levels which predict distinct magnetic fields and those which predict leukemia risk in the positive studies. Geographic locations and methods that refine wire codes as magnetic fields predictors also tend to strengthen the association with leukemia. Opposing arguments are based on the failure of the wire code-magnetic field association to predict the strength of association across studies, including the unexplained lack of association between wire codes and leukemia in the Midwest and in Canada. Alternatives to magnetic fields are less supported; residential mobility, social class, and neighborhood characteristics are unlikely to explain a wire code effect. Ambiguity persists because of the modest strength of the wire code-leukemia association, the complexity of the relation between wire codes and magnetic fields, lack of knowledge of risk factors for childhood leukemia, and the limited evaluation of wire code correlates other than magnetic fields.

An application of hierarchical regression in the investigation of multiple paternal occupational exposures and neuroblastoma in offspring

BACKGROUND

We used hierarchical regression to study the effects of 46 paternal occupational exposures on the incidence of neuroblastoma in offspring.

METHODS

The study population included 405 cases and 302 controls. The effect of each exposure was estimated using both conventional maximum likelihood and hierarchical regression.

RESULTS

Using hierarchical regression, overall precision was greatly enhanced compared to the conventional analysis. In addition, adjustment of effect estimates based on prespecified prior distributions of the true effect parameters allowed a more consistent interpretation across the entire panel of exposures. Estimates for several metals and solvents were shrunk close to the null value, whereas estimates for several thinner solvents, diesel fuel, solders, wood dust, and grain dust remained moderately elevated.

CONCLUSIONS

Hierarchical regression may mitigate some of the problems of the conventional approach by controlling for correlated exposures, enhancing the precision of estimates, and providing some adjustment of estimates based on prior knowledge.

A multicentre phase II pilot study of epirubicin and Taxol (paclitaxel) in patients with advanced breast cancer

Anthracyclines are the gold standard monotherapy for metastatic breast cancer. Higher response rates are seen with drug combinations, especially with newer agents such as taxanes. The purpose of this study was to evaluate the toxicity and activity of the combination of paclitaxel and epirubicin in patients with advanced breast cancer. Thirty-five women with locally advanced or metastatic breast cancer (first and second relapse) were treated with epirubicin 75 mg/m2 and paclitaxel 200 mg/m2 3-weekly. Six centres recruited 35 patients; 34 (97%) were assessable for response. Eighteen had undergone prior chemotherapy, including six (17%) with anthracycline-containing regimens. Grade 4 neutropenia was found in 33 patients (94%), which was of 4 days' average duration; however, infective complications were rare, with only nine cycles (6%) complicated by neutropenic sepsis. There were two sepsis-related deaths. Symptomatic cardiotoxicity was infrequent, although a >15% decline in cardiac function was recorded in five patients (14%). Grade 3 peripheral neuropathy occurred in three patients (9%). The overall response rate was 50% (95% confidence interval 33-67) (complete response 12%; partial response 38%), with a median duration of response of 31 weeks. The median time to progression was 27 weeks, with a median survival of 48 weeks. This regimen appears to be a relatively safe, tolerable and effective treatment for advanced breast cancer. A United Kingdom Co-ordinating Committee for Cancer Research Phase III trial (AB-01) comparing this combination of epirubicin and paclitaxel with cyclophosphamide and paclitaxel completed accrual in November 1999.

Looking back on "causal thinking in the health sciences"

It has now been over a quarter of a century since the publication of Mervyn Susser's Causal Thinking in the Health Sciences (1973, Oxford University Press), the first book-length treatment of causal reasoning and inference in our field. Major contributions of this work were its holistic focus on the origins of health outcomes in the context of ecologic systems and its invigoration of the literature on causal criteria in epidemiology. Although a recent resurgence of interest in social context has revivified many points made by Susser, a formal basis for causal analysis consistent with this ecologic perspective has failed to emerge in public health research. Susser's discussion of causal criteria, on the other hand, helped spur a vigorous dialogue that has persisted unabated to the present day. Although the basic outline of the criteria has evolved little, their applications, interrelations, and relative contributions to causal judgments have been the subject of continued and sometimes contentious debate.

A pooled analysis of magnetic fields, wire codes, and childhood leukemia. Childhood Leukemia-EMF Study Group

We obtained original individual data from 15 studies of magnetic fields or wire codes and childhood leukemia, and we estimated magnetic field exposure for subjects with sufficient data to do so. Summary estimates from 12 studies that supplied magnetic field measures exhibited little or no association of magnetic fields with leukemia when comparing 0.1-0.2 and 0.2-0.3 microtesla (microT) categories with the 0-0.1 microT category, but the Mantel-Haenszel summary odds ratio comparing >0.3 microT to 0-0.1 microT was 1.7 (95% confidence limits = 1.2, 2.3). Similar results were obtained using covariate adjustment and spline regression. The study-specific relations appeared consistent despite the numerous methodologic differences among the studies. The association of wire codes with leukemia varied considerably across studies, with odds ratio estimates for very high current vs low current configurations ranging from 0.7 to 3.0 (homogeneity P = 0.005). Based on a survey of household magnetic fields, an estimate of the U.S. population attributable fraction of childhood leukemia associated with residential exposure is 3% (95% confidence limits = -2%, 8%). Our results contradict the idea that the magnetic field association with leukemia is less consistent than the wire code association with leukemia, although analysis of the four studies with both measures indicates that the wire code association is not explained by measured fields. The results also suggest that appreciable magnetic field effects, if any, may be concentrated among relatively high and uncommon exposures, and that studies of highly exposed populations would be needed to clarify the relation of magnetic fields to childhood leukemia.

Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers

BACKGROUND

Animal and in vitro studies have provided evidence of an anticarcinogenic effect of active ingredients in garlic.

OBJECTIVE

The objective was to conduct meta-analyses of the epidemiologic literature on the association between garlic consumption and risk of stomach, colon, head and neck, lung, breast, and prostate cancers.

DESIGN

Meta-analyses were conducted for all cancers mutually and separately for colorectal and stomach cancers in relation to consumption of exclusively raw garlic, cooked garlic, or both (RC garlic). Eighteen studies reported a relative risk estimate for RC garlic consumption and cancer risk.

RESULTS

In the meta-analyses of colorectal and stomach cancer, the reference categories ranged from no consumption to consumption of 3.5 g/wk, whereas the highest categories ranged from any consumption to >28.8 g/wk. The average difference between the highest and lowest categories was 16 g/wk. The random-effects relative risk (RR) estimate of colorectal cancer and RC garlic consumption, excluding garlic supplements, was 0.69 (95% CI: 0.55, 0.89). For stomach cancer, the random-effects RR estimate was 0.53 (95% CI: 0.31, 0.92). The heterogeneity among studies for the latter outcome (P: = 0.0002) indicates the questionableness of the generalizability of this summary estimate. An indication of publication bias for all cancers combined is evident from a funnel plot of RC garlic consumption and cancer risk and from the results of the Begg and Mazumdar test (P: = 0.049).

CONCLUSIONS

High intake of RC garlic may be associated with a protective effect against stomach and colorectal cancers. Heterogeneity of effect estimates, differences in dose estimation, publication bias, and possible alternative hypotheses (eg, confounding by total vegetable consumption) preclude sole reliance on summary effect estimates.