Pilot Study of a Digital Behavioral Therapy for Overactive Bladder in Women

IMPORTANCE

The burden and high prevalence of overactive bladder (OAB) underline the urgent need for effective treatment. This study provides an initial look at an alternative approach to behavioral therapy for overactive bladder (OAB) that is delivered as an app on a smartphone.

OBJECTIVE

This study aimed to investigate feasibility, acceptability, and preliminary efficacy of a digital therapeutic for OAB.

STUDY DESIGN

This was a multicentered prospective pilot study. We used a convenience sample (N = 30) from waiting lists of women referred for incontinence, excluding urinary tract infections, urinary retention, bladder pain syndrome, pelvic cancer, current pregnancy, kidney disease, dementia, stroke, and prior neuromodulation. The intervention, a smartphone app, provided an 8-week program with weekly modules combining evidence-based knowledge videos and skill-building exercises that incorporated behavioral therapy, cognitive behavioral therapy, pelvic muscle training, and general health information. Combined scores on the International Consultation on Incontinence Questionnaire was the primary outcome measure. Secondary outcomes included improvement in quality of life, based on International Consultation on Incontinence Questionnaire, a 72-hour urinary diary, and Patient Global Impression of Improvement. We evaluated usability with the Mobile Application Rating Scale. Statistical tests included Shapiro-Wilk tests and paired-sample t tests.

RESULTS

Overall, 100% of participants reported a reduction in their OAB symptoms and 82% reported an improvement in quality of life. There was a significant improvement in diary parameters, including frequency (10.19-6.71 a day: SD, 1.25; P = 0.017) and incontinence (10-3.57: SD, 4.58). Participants rated the app highly on functionality, and 70% would recommend it. Patient Global Impression of Improvement improved for 72% of participants.

CONCLUSIONS

This study supports the application of a digital platform to over-come the real-world barriers for first-line treatment for OAB and offers information to inform further evaluation of the safety and efficacy of the NUIG OAB App.

Towards optimal use of antithrombotic therapy of people with cancer at the end of life: A research protocol for the development and implementation of the SERENITY shared decision support tool

BACKGROUND

Even though antithrombotic therapy has probably little or even negative effects on the well-being of people with cancer during their last year of life, deprescribing antithrombotic therapy at the end of life is rare in practice. It is often continued until death, possibly resulting in excess bleeding, an increased disease burden and higher healthcare costs.

METHODS

The SERENITY consortium comprises researchers and clinicians from eight European countries with specialties in different clinical fields, epidemiology and psychology. SERENITY will use a comprehensive approach combining a realist review, flash mob research, epidemiological studies, and qualitative interviews. The results of these studies will be used in a Delphi process to reach a consensus on the optimal design of the shared decision support tool. Next, the shared decision support tool will be tested in a randomised controlled trial. A targeted implementation and dissemination plan will be developed to enable the use of the SERENITY tool across Europe, as well as its incorporation in clinical guidelines and policies. The entire project is funded by Horizon Europe.

RESULTS

SERENITY will develop an information-driven shared decision support tool that will facilitate treatment decisions regarding the appropriate use of antithrombotic therapy in people with cancer at the end of life.

CONCLUSIONS

We aim to develop an intervention that guides the appropriate use of antithrombotic therapy, prevents bleeding complications, and saves healthcare costs. Hopefully, usage of the tool leads to enhanced empowerment and improved quality of life and treatment satisfaction of people with advanced cancer and their care givers.

The influence of patient size on the overall uncertainty in radiographic dose audit

The aim of this work was to investigate the effect of patient and cohort size on the overall uncertainty associated with dose audit using radiography of the abdomen as the exemplar. Water equivalent diameterDwwas used as the surrogate for patient size and its distribution (σ(Dw)) was used to quantify the effect of sample size. The more precise the kerma area product calibration, the more patients are required in the cohort to have the same impact on the overall uncertainty. Patient sample sizes of 300-400 will result in expanded uncertainties approaching the theoretical limit of double the measurement uncertainty when audits are performed with instruments having measurement uncertainties equal to ±7%, ±10% or ±12.5%. By way of example, for a field instrument with a measurement uncertainty of ±10%, a minimum sample size of 350 is required to achieve a total expanded uncertainty of ±21%. In the case of instruments with associated measurement uncertainty of ±3.5%, patient sample sizes of 300-400 will result in expanded uncertainties of approximately ±10%. From review of the literature and comparison with the results obtained here, it is conjectured that for radiographic dose audits of all parts of the trunk the contribution to overall uncertainty due to patient and sample size could be predicted using an indicative value forσ(Dw) of 3.4 where local data is not available.

More Robust Monitoring for Continuous Quality Improvement in Screening Programmes

Background and context: The National Screening Unit in the Ministry of Health is responsible for the safety, effectiveness, and quality of five formal screening programs in New Zealand: breast screening, cervical screening, bowel screening, newborn metabolic screening, and newborn hearing screening. Currently, each screening program has a set of standards against which performance is assessed. Each program is monitored through a range of avenues: formally reported indicators, audits, contract reporting, case reviews, etc. Aim: We aimed to review the existing monitoring across all the screening programs to: (a) Clarify what existing measures served what purpose, and for which audience (b) Review what was being captured through different monitoring avenues, to assess gaps and duplications (c) To better align our monitoring approach across all the screening programs. Strategy/Tactics: For each measure, we used a formal template to justify its existence, covering multiple aspects including rationale, lifespan, dimension of quality, screening pathway step, targets and associated evidence, thresholds for corrective action, and “owner” responsible for triggering quality improvement. We also mapped the screening program standards to various monitoring avenues to assess gaps and duplications. Program/Policy process: This process was timed to coincide with the need for developing monitoring for a new screening program (bowel screening), and revising monitoring for an established screening program undergoing a change (cervical screening switching to HPV testing as a primary screen). Outcomes: *anticipated outcomes in italics, will be completed by time of Congress* This process resulted in an overarching monitoring framework, which functions as a blueprint for screening-program-specific monitoring plans. What was learned: Screening programs have different monitoring requirements depending on what phase they are in (i.e., new versus changing versus established). Having clearly documented rationale ensures that every measure is justified and has an “evidence trail”. Having clearly documented audiences, thresholds and responsibilities for corrective action ensures that monitoring contributes to continuous quality improvement, rather than monitoring for monitoring's sake.

Henoch-Schönlein purpura and meningococcal B vaccination

The risk of Henoch-Schönlein purpura (HSP) following vaccination with a group B meningococcal vaccine was assessed through active hospital safety monitoring. There was no increase in the relative incidence of HSP within 30 days after vaccination nor recurrence in HSP cases who received one or more further vaccine doses (re-challenge).

BRCA1 gene expression signature predicts for anthracycline-chemosensitivity in triple-negative breast cancer

Abstract #6039

Background: We used a previously published gene expression signature that can identify tumors from BRCA1 mutation carriers to evaluate its predictive value in triple-negative breast cancer as a marker for chemosensitivity to anthracycline-based chemotherapy. We proposed that based on preclinical evidence suggesting that BRCA1-deficient breast cancer cells are sensitive to DNA damaging drugs such as cisplatin and anthracyclines this gene expression profile may identify tumors with anthracycline chemosensitivity. Two previously published studies defined a gene expression signature associated with BRCA1 germline mutation.(1,2) In these studies, sporadic tumors were misclassified as BRCA1 tumors and further analysis revealed methylation of the BRCA1 promoter region and decreased BRCA1 gene expression. This finding suggests the possibility of identifying sporadic tumors with decreased BRCA1 activity.
 Methods: We selected from our database of a locally advanced breast cancer neoadjuvant trial all cases of triple negative breast cancer that received 4 cycles of doxorubicin/cyclophosphamide(AC, 60/200 mg/m2, every 3 weeks) prior to surgery. Pathologic response to chemotherapy was disappearance of all invasive cancer or microscopic residual disease. Tumoral gene expression profile previously obtained using Affymetrix U133A Chip was analyzed for an optimal set of 100 most differentially expressed genes distinguishing BRCA1 and sporadic triple negative tumors according to the previously identified gene signature by van't Veer et al.1 We performed unsupervised clustering to determine if this signature could classify a subtype of triple-negative tumors with "BRCAness" and to test our hypothesis that BRCA1-like tumors are more sensitive to AC. We then performed a supervised analysis to determine the most differentially expressed genes that could prospectively identify triple-negative sporadic tumors with “BRCAness” and tumors from BRCA1 germline carriers that are sensitive to anthracyclines.
 Results: Of the 66 patients enrolled in our neoadjuvant trial, 12 patient's tumors were triple negative and received preoperative AC. By unsupervised clustering, the gene expression pattern associated with BRCA1 cancers subdivided these sporadic cancers in to two groups: Group A(6/7 pathologic responders), and group B(5/5 non-pathologic responders). By supervised analysis, the most differentially overexpressed gene from the BRCA1 profile for AC sensitivity was YWHAH(14-3-3 eta polypeptide), while DKK3(Inhibitor of Wnt and Notch signaling pathway) and RPL23A were most overexpressed in all cases with adriamycin-resistance(p<0.01).
 Discussion: Triple negative sporadic breast cancer displaying “BRCAness” appear to be sensitive to AC chemotherapy. YWHAH, DKK3, and RPL23A are differentially expressed in anthracycline-sensitive versus resistant tumors. These three genes can potentially identify triple-negative breast cancers that exhibit “BRCAness” and sensitivity to DNA-damaging chemotherapy such as cisplatin, anthracycline, or PARP inhibitors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6039.

Characteristics of a high-risk minority population

21141

Background: Black and Hispanic breast cancer patients have a worse outcome when compared to Caucasians. This could be due to socioeconomic, cultural or biologic factors. We hypothesized that host and tumor biologic characteristics associated with a poor outcome may be found more often in minority women. Methods: Race/ethnicity, menopausal status, tumor histological features, and patient characteristics including age and body mass index (BMI) were reviewed from a prospective neoadjuvant trial of docetaxel vs. doxorubicin/cyclophosphamide at Baylor College of Medicine Breast Center, from September 2002 to September 2006. The data were analyzed using Chi-square and Fisher's exact tests, while the Kruskal-Wallis method was used to analyze BMI. Results: Of the 167 patients, 63% (n=105) were Caucasian, 15% (n=26) were Hispanic and 22% (n=36) were Black. The mean age was 47.6 years (range: 30–72). Fifty-nine percent were premenopausal. Overall, mean BMI was 29, with Caucasians having a mean BMI of 27.5, Hispanics with 29.8 and Blacks with a BMI of 34.6 (P<0.001). Sixty-five percent of the Caucasians and 58% of Hispanics were ER+ or PR+ versus 44% of Blacks (P=0.09). Sixteen percent of Caucasians were HER-2 positive compared to 4% of Hispanics and 9% of Blacks (p=0.25). In addition, 22% of Caucasians and 38% of Hispanics were ER-, PR-, HER-2- compared to 50% of tumors from Blacks (p=0.007). There was a trend linking BMI and triple negative status in breast cancers, which did not achieve statistical significance (p=0.21). Conclusion: In this study we found that black and Hispanic women were more likely to be obese and have ER-, PR-, HER-2- tumor phenotypes, both of which have been associated with poorer outcomes. Ongoing studies are being performed to elucidate the link between clinical and biological characteristics and understand the underlying molecular mechanisms associated with these findings.

No significant financial relationships to disclose.

Gene expression profiles in formalin-fixed, paraffin-embedded (FFPE) core biopsies predict docetaxel chemosensitivity

538

Background: Docetaxel has one of the highest response rates as a single agent in breast cancer, but de novo resistance is frequent. Previously, we had identified a 92-gene expression pattern that predicted response to neoadjuvant docetaxel. Other studies have validated that a high Recurrence Score (RS) by the 21-gene RT-PCR assay is predictive of worse prognosis (Paik, NEJM 2004) but better response to chemotherapy (Gianni, JCO 2005). We investigated whether tumor gene expression of these 21 genes and other candidate genes can predict response to docetaxel. Methods: Core biopsies from 97 patients were obtained before treatment with neoadjuvant docetaxel (4 cycles, 100 mg/m2 q3 weeks). Baseline and post-treatment measurements of the primary breast cancers were recorded. Three 10-micron FFPE sections were submitted for quantitative RT-PCR assays of 192 genes that were selected from our previous work and the literature. Results: Of the 97 patients, 81 (84%) had sufficient invasive breast cancer, 80 (82%) had sufficient RNA for assay of 192 genes, and 72 (74%) had clinical response data. Mean age was 48.5 years, and the median tumor size was 6 cm. Clinical complete responses (CR) by RECIST were observed in 12 (17%), partial responses in 41 (57%), stable disease in 17 (24%), and progressive disease in 2 patients (3%). The concordance of IHC and RT-PCR results was >80% for ER, PgR, and HER2. By univariate logistic regression, a significant correlation (p<0.05) between gene expression and CR was observed for 14 genes. Notably, CYBA-1 involved in mitochondrial metabolism, identified by gene expression profiling, significantly predicted CR (p=0.006). CR was associated with lower expression of the ER gene group and higher expression of the proliferation gene group. Multivariate analysis indicated that panels of genes better predictors of docetaxel response. Of note, CR was more likely with high RS and less likely with a low RS (p=0.008). Conclusion: We have established molecular profiles for breast cancers either responding or not responding to neoadjuvant docetaxel. This technology is a potential predictive test for docetaxel sensitivity by using small amounts of FFPE material, and may reduce unnecessary treatment, toxicity, and cost for breast cancer patients.

[Table: see text]

Limited impact of tamoxifen following dose-intensive L-FAC multimodality therapy of breast cancer

10741

Background: Front-line dose-intensive L-FAC has demonstrated a favorable 5-year relapse free survival pattern (ASCO 2004 #739). Tamoxifen was given for 5 years to ER+ patients after L-FAC completion. We evaluated the impact of adding tamoxifen to L-FAC. By design, this pilot study excluded low-risk patients not candidates for chemotherapy. Methods: 109 breast cancer patients were enrolled (4 excluded due to treatment violations) from 6/1989 to 1/2003: 20 Stage I (S), 52 S-II, 22 S-III, for a total of 94 patients. 11 S-IV patients were excluded from survival analysis. Adverse tumor presentations included: ER- 49, PgR- 60, P53+ 24, non-diploid 39, histological grade III 37, CerbB2+ 33. L-FAC included 72 hour (h) iv infusion 400mg/m2/day (d) 5-fluorouracil (F) modulated by iv bolus 200mg/m2/d X3 leucovorin (L), concomitantly with 24h iv d1 600–1000mg/m2 cyclophosphamide (C), 48h iv d2 + d3 60mg/m2 doxorubicin (A). S-I and S-II were given 6 courses and 8 for S-III. Increasing A + C dose level and/or shortening treatment intervals < 3 weeks with growth factors provided intensification. 40 patients received tamoxifen. Results: At a median follow-up of 74 months (range 9–214), 73 (78%) are alive (1 with relapse). Relapse free survival was: S-I 95%, S-II 81%, S-III 78%. At average course intervals of 18 days, dose intensity A/C mg/m2/wk was 24.2 / 335.4 with evidence of WHO grade III/IV stomatitis in 43%, neutropenia 59%, cumulative thrombocytopenia 50%, hand-foot syndrome 32% of patients. Aside from delayed relapse associated with tamoxifen, relapse-free survival >82 months was similar with and without tamoxifen. No relapse was observed after >53 months in ER- tumors despite showing higher frequency of adverse tumor risk factors. Conclusion: The impact of adding tamoxifen appears quite limited in a patient population with adverse tumor presentation treated with dose-intensive L-FAC.

No significant financial relationships to disclose.

Conventional and toxicogenomic assessment of the acute pulmonary damage induced by the instillation of Cardiff PM10 into the rat lung

There is strong epidemiological evidence of association between PM10 (particulate matter with an aerodynamic diameter less than or equal to 10 microm) and adverse health outcomes including death and increased hospital admissions for cardiopulmonary conditions. Ambient PM10 surrogates such as diesel exhaust particles (DEP), a common component of UK PM10 have been shown to induce lung inflammation in both humans and rodents. To date, few studies have reported on the toxicological response of UK PM10 in experimental animals. This study examines the pulmonary toxicological responses in male Sprague Dawley rats following the intratracheal instillation of Cardiff urban PM10. A mild but significant change in lung permeability was observed in the lung post-instillation of a high (10 mg) dose of the whole PM10 as adjudged by increases in lung to body weight ratio and total acellular lavage protein. Such effects were less marked following instillation of a water-soluble fraction (80% of the total mass) but histological examination showed that lung capillaries were swollen in size with this treatment. In conclusion, conventional toxicological, histological and toxicogenomic studies have indicated that Cardiff PM10 exhibits low bioreactivity in the form of mild permeability changes. Differential gene expression was observed when the lung was treated with whole PM10, containing durable particles, in comparison with the water-soluble fraction of PM10 that was devoid of particles. Such changes were linked to different histopathological events within the lung.

Quantitative analysis of children's microactivity patterns: The Minnesota Children's Pesticide Exposure Study

The National Human Exposure Assessment Survey (NHEXAS)/Minnesota Children's Pesticide Exposure Study (MNCPES) was a population-based study designed to characterize children's exposure to residential pesticides and to evaluate the contribution of residential and children's activities to children's exposure. Families of 168 children were surveyed for residential use of pesticides and children's activities. From these homes, families of 102 children between the ages of 3 and 13 years participated in a week-long intensive exposure study. Of the 102 children, 19 children were videotaped for four consecutive hours in their normal daily activities. The survey responses indicated that the youngest children were more likely to exhibit behaviors that would foster exposure to environmental contaminants. Comparison of questionnaire responses indicated that the videotaped subsample was representative of the exposure study population. The microactivities of the videotaped children that might contribute to their exposure via ingestion or dermal routes were quantified. Hand-to-mouth and object-to-mouth activities were observed most frequently among the youngest children. The youngest children were also most likely to be barefoot both indoors and outside. Gender differences were found in mouthing behavior and the proportion of observed time spent outdoors.

Metabolites of a tobacco-specific lung carcinogen in the urine of elementary school-aged children

Limited data are available in the literature on carcinogen uptake by children exposed to environmental tobacco smoke (ETS). In this study, we quantified metabolites of the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in the urine of elementary school-aged children participating in the School Health Initiative: Environment, Learning, Disease study, a school-based investigation of the environmental health of children. The metabolites of NNK are 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide (NNAL-Gluc). We also measured cotinine and its glucuronide (total cotinine). Urine samples were collected from 204 children. Seventy (34.3%) of these had total cotinine > or =5 ng/ml. NNAL or NNAL-Gluc was detected in 52 of 54 samples with total cotinine > or =5 ng/ml and in 10 of 20 samples with total cotinine < 5 ng/ml. Levels of NNAL plus NNAL-Gluc and total cotinine were significantly higher when exposure to ETS was reported than when no exposure was reported. However, even when no exposure to ETS was reported, levels of NNAL, NNAL-Gluc, and NNAL plus NNAL-Gluc were higher than in children with documented low exposure to ETS, as determined by cotinine levels < 5 ng/ml. Levels of NNAL, NNAL-Gluc, and cotinine were not significantly different in samples collected twice from the same children at 3-month intervals. Levels of NNAL plus NNAL-Gluc in this study were comparable with those observed in our previous field studies of adults exposed to ETS. There was a 93-fold range of NNAL plus NNAL-Gluc values in the exposed children. The results of this study demonstrate widespread and considerable uptake of the tobacco-specific lung carcinogen NNK in this group of elementary school-aged children, raising important questions about potential health risks. Our data indicate that objective biomarkers of carcinogen uptake are important in studies of childhood exposure to ETS and cancer later in life.

Measurement of children's exposure to pesticides: analysis of urinary metabolite levels in a probability-based sample

The Minnesota Children's Pesticide Exposure Study is a probability-based sample of 102 children 3-13 years old who were monitored for commonly used pesticides. During the summer of 1997, first-morning-void urine samples (1-3 per child) were obtained for 88% of study children and analyzed for metabolites of insecticides and herbicides: carbamates and related compounds (1-NAP), atrazine (AM), malathion (MDA), and chlorpyrifos and related compounds (TCPy). TCPy was present in 93% of the samples, whereas 1-NAP, MDA, and AM were detected in 45%, 37%, and 2% of samples, respectively. Measured intrachild means ranged from 1.4 microg/L for MDA to 9.2 microg/L for TCPy, and there was considerable intrachild variability. For children providing three urine samples, geometric mean TCPy levels were greater than the detection limit in 98% of the samples, and nearly half the children had geometric mean 1-NAP and MDA levels greater than the detection limit. Interchild variability was significantly greater than intrachild variability for 1-NAP (p = 0.0037) and TCPy (p < 0.0001). The four metabolites measured were not correlated within urine samples, and children's metabolite levels did not vary systematically by sex, age, race, household income, or putative household pesticide use. On a log scale, mean TCPy levels were significantly higher in urban than in nonurban children (7.2 vs. 4.7 microg/L; p = 0.036). Weighted population mean concentrations were 3.9 [standard error (SE) = 0.7; 95% confidence interval (CI), 2.5, 5.3] microg/L for 1-NAP, 1.7 (SE = 0.3; 95% CI, 1.1, 2.3) microg/L for MDA, and 9.6 (SE = 0.9; 95% CI, 7.8, 11) microg/L for TCPy. The weighted population results estimate the overall mean and variability of metabolite levels for more than 84,000 children in the census tracts sampled. Levels of 1-NAP were lower than reported adult reference range concentrations, whereas TCPy concentrations were substantially higher. Concentrations of MDA were detected more frequently and found at higher levels in children than in a recent nonprobability-based sample of adults. Overall, Minnesota children's TCPy and MDA levels were higher than in recent population-based studies of adults in the United States, but the relative magnitude of intraindividual variability was similar for adults and children.

Measurement of children's exposure to pesticides: analysis of urinary metabolite levels in a probability-based sample

The Minnesota Children's Pesticide Exposure Study is a probability-based sample of 102 children 3-13 years old who were monitored for commonly used pesticides. During the summer of 1997, first-morning-void urine samples (1-3 per child) were obtained for 88% of study children and analyzed for metabolites of insecticides and herbicides: carbamates and related compounds (1-NAP), atrazine (AM), malathion (MDA), and chlorpyrifos and related compounds (TCPy). TCPy was present in 93% of the samples, whereas 1-NAP, MDA, and AM were detected in 45%, 37%, and 2% of samples, respectively. Measured intrachild means ranged from 1.4 microg/L for MDA to 9.2 microg/L for TCPy, and there was considerable intrachild variability. For children providing three urine samples, geometric mean TCPy levels were greater than the detection limit in 98% of the samples, and nearly half the children had geometric mean 1-NAP and MDA levels greater than the detection limit. Interchild variability was significantly greater than intrachild variability for 1-NAP (p = 0.0037) and TCPy (p < 0.0001). The four metabolites measured were not correlated within urine samples, and children's metabolite levels did not vary systematically by sex, age, race, household income, or putative household pesticide use. On a log scale, mean TCPy levels were significantly higher in urban than in nonurban children (7.2 vs. 4.7 microg/L; p = 0.036). Weighted population mean concentrations were 3.9 [standard error (SE) = 0.7; 95% confidence interval (CI), 2.5, 5.3] microg/L for 1-NAP, 1.7 (SE = 0.3; 95% CI, 1.1, 2.3) microg/L for MDA, and 9.6 (SE = 0.9; 95% CI, 7.8, 11) microg/L for TCPy. The weighted population results estimate the overall mean and variability of metabolite levels for more than 84,000 children in the census tracts sampled. Levels of 1-NAP were lower than reported adult reference range concentrations, whereas TCPy concentrations were substantially higher. Concentrations of MDA were detected more frequently and found at higher levels in children than in a recent nonprobability-based sample of adults. Overall, Minnesota children's TCPy and MDA levels were higher than in recent population-based studies of adults in the United States, but the relative magnitude of intraindividual variability was similar for adults and children.

Residential proximity to industrial sources of air pollution: interrelationships among race, poverty, and age

This study builds on earlier work investigating statistical relationships between sociodemographic characteristics of populations and their residential proximity to industrial sources of air pollution. The analysis uses demographic data from the 1990 U.S. Census and industrial site data from the U.S. Environmental Protection Agency (EPA)'s 1990 Toxics Release Inventory (TRI). The focus is on examining interactions among race (African Americans and Whites), poverty (above and below household poverty threshold), and age (children from birth to 5 years of age and elderly people 65 years old or older). Results from three different study areas (Kanawha Valley in West Virginia, the Baton Rouge-New Orleans Corridor in Louisiana, and the greater Baltimore metropolitan area in Maryland) suggest there are important interactions among race, poverty, and age that are likely to have consequential ramifications for efforts aimed at investigating issues related to environmental justice. Our results indicate that a substantial proportion of all demographic groups studied live within a mile of the nearest facility, with values ranging from 22% of Whites above poverty in the Baton Rouge-New Orleans Corridor to 60% of African Americans below poverty in Baltimore. Likewise, a substantial proportion of all demographic groups also live within 2 miles of four or more industrial facilities, with values ranging from 16% for Whites above poverty in the Corridor to 70% for African Americans below poverty in Baltimore. In all three study areas, African Americans were more likely than Whites to (1) live in households with incomes below the household poverty line, (2) have children 5 years of age or younger, (3) live closer to the nearest industrial emissions source, and (4) live within 2 miles of multiple industrial emission sources. Findings indicate that, compared with White children, a substantially higher proportion of African-American children 5 years of age or younger lived in poor households that were located in relatively close proximity to one or more industrial sources of air pollution.

Measurement of multi-pollutant and multi-pathway exposures in a probability-based sample of children: practical strategies for effective field studies

The purpose of this manuscript is to describe the practical strategies developed for the implementation of the Minnesota Children's Pesticide Exposure Study (MNCPES), which is one of the first probability-based samples of multi-pathway and multi-pesticide exposures in children. The primary objective of MNCPES was to characterize children's exposure to selected pesticides through a combination of questionnaires, personal exposure measurements (i.e., air, duplicate diet, hand rinse), and complementary monitoring of biological samples (i.e., pesticide metabolites in urine), environmental samples (i.e., residential indoor/outdoor air, drinking water, dust on residential surfaces, soil), and children's activity patterns. A cross-sectional design employing a stratified random sample was used to identify homes with age-eligible children and screen residences to facilitate oversampling of households with higher potential exposures. Numerous techniques were employed in the study, including in-person contact by locally based interviewers, brief and highly focused home visits, graduated subject incentives, and training of parents and children to assist in sample collection. It is not feasible to quantify increases in rates of subject recruitment, retention, or compliance that resulted from the techniques employed in this study. Nevertheless, results indicate that the total package of implemented procedures was instrumental in obtaining a high percentage of valid samples for targeted households and environmental media.

A school-based strategy to assess children's environmental exposures and related health effects in economically disadvantaged urban neighborhoods

The School Health Initiative: Environment, Learning, Disease (SHIELD) study is a novel school-based investigation of children's environmental health in economically disadvantaged urban neighborhoods of Minneapolis. This article describes the study design and summarizes lessons learned about recruiting and monitoring this historically understudied population. The SHIELD study focused on measuring children's exposures to multiple environmental stressors [volatile organic chemicals (VOCs), environmental tobacco smoke, allergens, bioaerosols, metals, pesticides, polychlorinated biphenyls (PCB), phthalates] and exploring related effects on respiratory health (e.g., lung function) and learning outcomes (e.g., standardized test scores, academic achievement). It involved intensive exposure monitoring, including environmental measurements inside and outside the children's schools and inside their homes, personal measurements with passive dosimeters worn by the children, and biological marker measurements in blood and urine. The SHIELD participants comprised a stratified random sample of 153 "index" children and 51 of their siblings enrolled in grades 2-5 at two adjacent elementary schools. The Minneapolis Public Schools (MPS) assisted with identifying, contacting, recruiting, and monitoring this population, which traditionally is difficult to study because families/children are highly mobile, speak a diversity of languages, frequently do not have a telephone, endure economic hardships, often do not trust researchers, and have a spectrum of unconventional lifestyles and living arrangements. Using a school-based approach, the overall SHIELD enrollment (response) rate was 56.7%, with a wide disparity between English-speaking (41.7%) and non-English-speaking (71.0%) families/children. Most children remained involved in the study through both monitoring sessions and exhibited an acceptable degree of compliance with study protocols, including providing blood and urine samples. Results indicate that it is both practical and affordable to conduct probability-based exposure studies in this population, but that it is also important to improve our understanding of factors (e.g., cultural, economic, psychological, social) affecting the willingness of families/children to participate in such studies, with special emphasis on developing cost-effective recruitment methods.

Assessing children's exposure to hazardous environmental chemicals: an overview of selected research challenges and complexities

There is renewed interest in the United States regarding characterization of children's exposures to hazardous environmental chemicals. Many studies are currently underway that use novel and innovative approaches to assess childhood exposures to a variety of toxic chemicals, including both persistent and nonpersistent compounds. This article reviews some of the critical challenges that can impede scientifically rigorous studies designed to measure children's environmental exposures. The discussion briefly examines three topical areas: administrative issues (IRB approval, participant incentives, community involvement, and communication of results to research participants and stakeholders); data-collection issues (identifying and recruiting children/families, measuring actual exposures/doses); and issues related to chemical analysis of biological samples (examples of chemicals and chemical classes that can be measured in human tissue and excreta, effects of a child's age on the type and amount of biological samples available for analysis). These research complexities are discussed in the context of developing more effective and efficient exposure assessment methods.

Comparison of short-term variations (15-minute averages) in outdoor and indoor PM2.5 concentrations

Measurements of 15-min average PM2.5 concentrations were made with a real-time light-scattering instrument at both outdoor (central monitoring sites in three communities) and indoor (residential) locations over two seasons in the Minneapolis-St. Paul metropolitan area. These data are used to examine within-day variability of PM2.5 concentrations indoors and outdoors, as well as matched indoor-to-outdoor (I/O) ratios. Concurrent gravimetric measurements of 24-hr average PM2.5 concentrations were also obtained as a way to compare real-time measures with this more traditional metric. Results indicate that (1) within-day variability for both indoor and outdoor 15-min average PM2.5 concentrations was substantial and comparable in magnitude to day-to-day variability for 24-hr average concentrations; (2) some residences exhibited substantial variability in indoor aerosol characteristics from one day to the next; (3) peak values for indoor short-term (15-min) average PM2.5 concentrations routinely exceeded 24-hr average outdoor values by factors of 3-4; and (4) relatively strong correlations existed between indoor and outdoor PM2.5 concentrations for both 24-hr and 15-min averages.

House dust levels of selected insecticides and a herbicide measured by the EL and LWW samplers and comparisons to hand rinses and urine metabolites

During the Minnesota Children's Pesticide Exposure Study (MNCPES), comparisons were made between the insecticide/herbicide loadings obtained with two household dust/insecticide or herbicide samplers: the Edwards and Lioy (EL) press sampler (used for dust collection from carpets or other surfaces) and the Lioy, Waimnan and Weisel (LWW) surface wipe sampler. The results were compared with hand rinse levels, and urine metabolite levels obtained from 102 children (ages 3-13). All measurements were made during a 1-week sampling period, and information was obtained on household pesticide use and each child's activities. Of the homes, <5% had recent spot uses of a pesticide but none had recent general applications. The analyses focused primarily on atrazine (a herbicide), and malathion, diazinon, and chlorpyrifos (insecticides). Metabolites were measured for atrazine, malathion and chlorpyrifos. The atrazine levels obtained using the EL indicate that this compound was transported into the home by an unquantified transport mechanism (e.g. tracking of soil). Two malathion hand rinse values exceeded >170 ng/cm2, suggesting that since indoor surface levels were low, these children had other sources of exposure. Atrazine, chlorpyrifos and malathion were detectable in >30% of the homes by the EL, LWW or hand rinse. Only chlorpyrifos had detectable levels in > or = 50% of the samples for all types, i.e. compound or metabolite, which is consistent with it being a common household pesticide. The median (and maximum) chlorpyrifos levels for the EL surface, EL carpet, LWW surface (two rooms), hand rinse, and urine metabolites were: 0.07 (32.6) ng/cm2; 0.07 (44.5) ng/cm2; 0.34 (3.64) ng/cm2; 0.42 (14.4) ng/cm2; 0.03 (2.14) ng/hand and 6.9 (59.0) microg/g, respectively. A strong correlation was found for chlorpyrifos between the EL surface and carpet samples. Chlorpyrifos levels detected by LWW had a different distribution and concentration range than the EL, indicating that it collected more than the surface dislodgeable insecticide. EL was directly comparable to the hand rinse or urine levels, but only the LWW had a weak correlation with hand rinse levels, suggesting that the children had other sources of chlorpyrifos exposure. Thus, mechanistic exposure studies are needed to more accurately establish exposure dose relationships in residential settings.

Design strategy for assessing multi-pathway exposure for children: the Minnesota Children's Pesticide Exposure Study (MNCPES)

Although children are exposed to a variety of environmental hazards, including pesticides, there is a scarcity of information available to estimate exposures realistically. This article reports on one of the first attempts to measure multi-pathway pesticide exposures in a population-based sample of urban and non-urban children. A design strategy was developed to assess multi-pathway pesticide exposures in children using personal exposure measurements in combination with complimentary measurements of biological markers of exposure, concentrations in relevant environmental media, and time spent in important microenvironments and participating in exposure-related activities. Sample collection and analysis emphasized measurement of three insecticides (i.e., chlorpyrifos, diazinon, and malathion) and one herbicide (i.e., atrazine). These compounds were selected because of their frequent use, presence in multiple environmental media, expected population exposures, and related hazard/toxicity. The study was conducted during the summer of 1997 in Minnesota and involved a stratified sample of households with children ages 3-12 years. Participants resided in either (a) the cities of Minneapolis and St. Paul (urban households), or (b) Rice and Goodhue Counties just south of the metropolitan area (non-urban households). Results from a residential inventory documenting storage and use of products containing the target pesticides were used to preferentially select households where children were likely to have higher exposures. The study successfully obtained pesticide exposure data for 102 children, including measurements of personal exposures (air, hand rinse, duplicate diet), environmental concentrations (residential indoor/outdoor air, drinking water, residential surfaces, soil), activity patterns (obtained by questionnaire, diary, videotaping), and internal dose (metabolites in urine).

Pesticide storage and use patterns in Minnesota households with children

As part of the National Human Exposure Assessment Survey (NHEXAS), residential pesticide storage and use patterns were evaluated in a population-based sample of Minnesota households with children aged 3-13. In-home interviews and inventories were conducted to identify pesticide products stored and used in and around 308 households. This statistically based sample represents more than 49,000 urban and rural households in the census tracts sampled. More than 850 unique products were identified using Environmental Protection Agency (EPA) registration numbers. Pesticide products were found in 97% and reported used in 88% of study households. Population-weighted mean values for pesticide storage and use were 6.0 and 3.1 products per household, respectively. The most common active ingredients found were diethyl toluamide (DEET) and related compounds, piperonyl butoxide, pyrethrins, dimethylamine 2-[2-methyl-4-chlorophenoxyl propionate (MCPA) and chlorpyrifos. Household socio-demographic characteristics explained little of the variability in pesticide storage and use patterns, and there were no significant differences in residential storage and use patterns between households located in urban versus non-urban census tracts. Although the prevalence of households with pesticide products was similar to recent national surveys, observed storage and use rates were almost twice those obtained in recent national studies, reflecting improved inventory techniques used by this study and/or increased rates of pesticide presence and use in study households.

Adulteration of urine by "Urine Luck"

BACKGROUND

In vitro adulterants are used to invalidate assays for urine drugs of abuse. The present study examined the effect of pyridinium chlorochromate (PCC) found in the product "Urine Luck".

METHODS

PCC was prepared and added to positive urine controls at concentrations of 0, 10, 50, and 100 g/L. The controls were assayed for methamphetamine, benzoylecgonine (BE), codeine and morphine, tetrahydrocannabinol (THC), and phencyclidine (PCP) with the Emit II (Syva) and Abuscreen Online (Roche) immunoassays, and by gas chromatography/mass spectrometry (GC/MS). Two tests were also developed to detect PCC in urine: a spot test to detect chromate ions using 10 g/L 1,5-diphenylcarbazide as the indicator, and a GC/MS assay for pyridine. We tested 150 samples submitted for routine urinalysis, compliance, and workplace drug testing for PCC, using these assays.

RESULTS

Response rates decreased at 100 g/L PCC for all Emit II drug assays and for the Abuscreen morphine and THC assays. In contrast, the Abuscreen amphetamine assay produced apparently higher results, and no effect was seen on the results for BE or PCP. The PCC did not affect the GC/MS recovery of methamphetamine, BE, PCP, or their deuterated internal standards, but decreased GC/MS recovery of the opiates at both intermediate (50 g/L) and high (100 g/L) PCC concentrations and apparent concentrations of THC and THC-d3 at all PCC concentrations. Two of 50 samples submitted for workplace drug testing under chain-of-custody conditions were positive for PCC, whereas none of the remaining 100 specimens submitted for routine urinalysis or compliance drug testing were positive.

CONCLUSIONS

PCC is an effective adulterant for urine drug testing of THC and opiates. Identification of PCC use can be accomplished with use of a spot test for the oxidant.

Looking at environmental justice from an environmental health perspective

Although scientific evidence is scarce and uneven, there are mounting concerns that environmental health risks are borne disproportionately by members of the population who are poor and nonwhite. From an environmental health perspective, research to reduce critical uncertainties in health risk assessment must necessarily be at the heart of efforts to evaluate and resolve issues of environmental justice--helping to define the dimensions of the problem, understand its causes, and identify effective and efficient solutions. The full range of environmental health sciences, including exposure analysis, epidemiology, toxicology, biostatistics, and surveillance monitoring, is needed to build a strong scientific foundation for informed decision making. This is the best and surest way to promote health and safety for all members of our society, regardless of age, ethnicity, gender, health condition, race, or socioeconomic status.

An examination of race and poverty for populations living near industrial sources of air pollution

This study examines the sociodemographic characteristics of people living near industrial sources of air pollution in three areas of the United States: (1) the Kanawha Valley in West Virginia: (2) the Baton Rouge-New Orleans corridor in Louisiana: and (3) the greater Baltimore metropolitan area in Maryland. Using data from the 1990 Toxics Release Inventory (TRI) and the 1990 Census, we analyze relationships between variables assumed to be independent, such as location of single or multiple industrial emission sources, and the dependent variables of race (black/white) and poverty status (above/below poverty level). Results from all three study areas are consistent and indicate that African Americans and those living in households defined to be below the established poverty level are more likely, on average, to live closer to the nearest TRI facility and to live within 2 miles of multiple TRI facilities. Conversely, whites and those living in households above the poverty level are more likely, on average, to live farther from the nearest TRI facility and to live within 2 miles of fewer facilities, compared to African Americans and poor people.

Science and policy implications of defining environmental justice

Although 'environmental justice' is an increasingly important issue for policy makers and researchers, it remains for many a vague and abstract notion that is hard to define in practical, real-world terms. Part of the problem is that environmental justice is a complex, multidimensional construct that cannot easily be defined. Our aim in this article is to identify fundamental dimensions of environmental justice and highlight the resulting questions that are an inherent part of putting principles into practice. We argue that to have a constructive and informed debate about this emotionally charged topic, it is necessary to have a clear and workable definition of environmental justice. We do not propose our own definition, but instead point out that there are many possible legitimate definitions depending on one's beliefs, opinions, and values. The central point is not that a particular definition is right or wrong, but rather than choosing a definition has distinct implications for the formulation, implementation, and evaluation of both policy and science. These critical choices should be made explicit so that public dialogue can focus on the substance of this important policy issue.

Neutralization of beta-lactam antibiotics in an environmental monitoring medium

The neutralizing ability of Difco Bacto Penase, BBL Penicillinase, and Genzyme beta-lactamase for penicillin G, oxacillin, cephalothin, cefazolin, ceftazidime, ceftriaxone, cefotaxime, imipenem, and meropenem was determined in an agar medium. Trypticase soy agar plates (20 mL) containing 200 MU/L Difco Penase, 200 MU/L BBL Penicillinase, or 2 vials/L of Genzyme beta-lactamase were dosed with 20, 50, and 100 micrograms of each antibiotic and then inoculated (50-100 CFU/plate) with a susceptible microorganism. Percentage recoveries of the organism were calculated after incubation. Genzyme beta-lactamase effectively neutralized 100 micrograms of all the antibiotics except ceftazidime (32% recovery with 20 micrograms). The two penicillinases effectively neutralized 100 micrograms of penicillin G, oxacillin, cephalothin, and cefazolin; were slightly effective against ceftriaxone and cefotaxime (20-57% recovery with 20 micrograms); and totally ineffective against ceftazidime, imipenem, and meropenem. This investigation resulted in a useful procedure for qualifying and/or selecting a beta-lactamase for use in environmental monitoring medium to neutralize a particular beta-lactam.

Sociodemographic aspects of human susceptibility to toxic chemicals: Do class and race matter for realistic risk assessment?

Susceptibility is well-recognized as a potentially important aspect of health risk assessment, particularly for groups such as pregnant women and their fetuses, infants, children, the elderly, and the infirm, that are known or suspected to be more vulnerable to environmental insults. More recently, it has become apparent that economically disadvantaged groups are likely to be systematically both more exposed and more susceptible to environmental pollution. This article reviews the reasons why low-income communities and many racial minorities are at an increased risk because they are more susceptible to the adverse health effects of toxic chemicals. The scientific challenges of quantifying the magnitude of environmental health risks for these groups are discussed, emphasizing ramifications for risk assessment and risk management decisions. Problems incorporating susceptibility into risk-based decision making are identified, and specific actions are recommended to address these deficiencies.

What can research contribute to regulatory decisions about the health risks of multiple chemical sensitivity?

Multiple Chemical Sensitivity (MCS), which may not be caused by chemicals at all, is a serious medical problem of unknown origin and uncertain etiology that raises many fundamental science and policy questions. Regulators, for example, are confronted with a dilemma: what, if anything, should be done to protect people from the scientifically uncertain health risks of exposures to extremely low levels of environmental chemicals. Regulatory agencies, such as the Environmental Protection Agency, do not have the luxury of waiting until conclusive scientific evidence is available before making a decision; however, our present lack of scientific understanding about MCS is so acute that it is not possible to ascertain whether the cause of MCS-related symptoms is chemical, biological, physical, psychosocial, or some combination thereof. Nevertheless, many MCS sufferers and advocates for the chemically induced hypothesis are clamoring for regulatory action to reduce putative health risks from very-low-level exposures to chemicals in the environment. Unless steps are taken to improve the quantity and quality of the existing scientific data base, we cannot, with any acceptable degree of certainty, evaluate the extent to which regulatory decisions about MCS are either protective of public health or cost-effective. This article examines how research can strengthen the scientific basis for risk-related decisions about MCS, and proposes a framework for establishing research directions and priorities. It is argued that high-priority research on MCS is distinguishable by four attributes: (1) results are valuable for risk-related decisions; (2) findings significantly advance scientific knowledge and understanding; and the hypothesis being tested is both (3) biologically plausible and (4) readily testable.

Chemical mixtures from a public health perspective: the importance of research for informed decision making

When considered from a public health perspective, the central question regarding chemical mixtures is deceptively simple: Are current approaches to risk assessment for chemical mixtures affording effective (adequate) and efficient (cost-effective) protection for members of our society? Answering this question realistically depends on an understanding of the hierarchical goals of public health (i.e. prevention, intervention, treatment) and an accurate evaluation of the extent to which these goals are being achieved. To allow decision makers to make informed judgments about the health risks of chemical mixtures, adequate scientific knowledge and understanding must be available to support risk assessment activities, which are an integral part of the regulatory decision making process. Designing and implementing relevant research depends on the existence of a feedback loop between researchers and regulators, where the information needs of regulators influence the nature and direction of research and the information and understanding generated by researchers improves the scientific basis for public health decisions. A clear, consistent, commonly accepted taxonomy for describing important mixture-related phenomena is a key factor in creating and maintaining the necessary feedback loop. Ultimately, both researchers and regulators share a common goal with regard to chemical mixtures; improving the state-of-the-science so that we can make informed decisions about protecting public health. A survey of research issues and needs that are crucial to attaining this goal is presented.

Science and policy in regulatory decision making: getting the facts right about hazardous air pollutants

Hazardous air pollutants are regulated under Title III of the 1990 Clean Air Act Amendments. The Amendments replace the risk-based approach mandated in the 1977 Amendments with a prescriptive, technology-based approach requiring that maximum achievable control technology (MACT) be applied to all major industrial sources of 189 hazardous air pollutants. The change reflects political, rather than scientific consensus that the public health benefits justify the costs. The choice is put into perspective by looking at the interface between science and policy that occurs as part of regular decisionmaking. Particular emphasis is given to examining the interrelationships among facts (science), judgments (science policy), and policy (values) in the context of the risk assessment paradigm. Science and policy are discussed in relation to Title III, contrasting the political consensus for action with the scientific uncertainty about risks and benefits. It is argued that a balanced research program is needed to get the facts right about hazardous air pollutants, including research to meet statutory requirements, to reduce uncertainties in risk assessment, and to address strategic issues.

Research to strengthen the scientific basis for health risk assessment: a survey of the context and rationale for mechanistically based methods and models

Assessment of health risks is an integral part of regulatory decision-making that occurs at the interface between science (e.g. facts) and policy (e.g. values). Because existing scientific knowledge and understanding are often inadequate to answer the most critical risk-related questions, regulatory agencies have developed sets of formalized 'science policies' to extrapolate from existing data to real-life events and situations. These science policies, as, for example, the use of default assumptions or exposure scenarios, can introduce significant uncertainties into the final risk estimate. We survey the rationale for research to reduce extrapolation-related uncertainties, focusing specifically on the need to develop mechanistically based methods and models, including test methods to identify and characterize health effects, integrated human exposure models, physiologically based pharmacokinetic (PBPK) models and biologically based dose-response (BBDR) models.

Improving exposure assessment by monitoring human tissues for toxic chemicals

Typically, the availability of appropriate data to estimate human exposures to toxic chemicals is scarce. Consequently, exposure assessments are often based on indirect surrogates of exposure, such as a combination of questionnaire data on time-activities and concentrations of toxic chemicals measured in environmental media (e.g., air, water, food, soil, dust). Recent advances, however, make it technically feasible and relatively affordable to measure low levels of multiple toxic chemicals in accessible human tissues (e.g., blood, urine). The increasing availability of biological markers for exposure, along with improvements in pharmacokinetic understanding, present new opportunities to estimate exposure from human tissue measurements and from knowledge of intake and uptake parameters. Biological monitoring provides exposure information that is usually complementary to the type of exposure information obtained from environmental monitoring. Biological and environmental monitoring can be used separately or together in order to meet desired objectives. We present here a discussion of the value of biological monitoring for improving exposure assessment. We emphasize the role of biological monitoring in identifying high-priority exposures, evaluating the effectiveness of intervention and prevention efforts, identifying at-risk subpopulations, recognizing time trends in population exposures, establishing reference ranges of tissue concentrations, and providing integrated dose measurements.

Informed decisions about protecting and promoting public health: rationale for a National Human Exposure Assessment Survey

Accurate and reliable exposure-related information is essential for informed decisions about protecting and promoting public health. The need for more and better data on population exposures to environmental chemicals is discussed, with emphasis on the justification for collecting baseline data on exposure distributions for the general population and for important population subgroups. A rationale is provided for undertaking exposure surveillance in the U.S. population by means of a National Human Exposure Assessment Survey (NHEXAS). The knowledge and understanding generated by NHEXAS will contribute to more informed and more credible decisions in three ways: (1) by establishing a core set of approaches, methods, and data that will significantly advance the field of exposure analysis; (2) by developing a strong and direct connection between science (exposure research and surveillance) and policy (decisions about assessment, management, and communication of health risks); and (3) by creating a connected group of researchers and regulators who share a mutual appreciation and understanding of the value of exposure surveillance for well-reasoned decisions.

Integrating science and policy in a National Human Exposure Assessment Survey

Despite tremendous progress in environmental protection over the past two decades, critical gaps remain in our understanding of actual human exposures to environmental chemicals. While the research community and the policy makers share the common goal of reducing environmental risks, it must be recognized that their information needs are often divergent. The design of effective exposure research must consider the needs and practical limitations of regulators and policy-makers and balance the often conflicting needs of policy and science. This paper examines some of the inherent conflicts between exposure research (science) and regulatory (policy) realities, and describes how the needs of policy makers were integrated into the design of a National Human Exposure Assessment Survey (NHEXAS). NHEXAS represents perhaps the most ambitious exposure surveillance effort ever undertaken. Exposure surveillance is presented as a model for bridging the gap between policy and science in the development of risk management approaches. The success of risk-based priority setting will depend upon the quality of information to support the risk assessment process. Environmental exposure surveillance will be essential to the characterization of risks and, ultimately, to the evaluation of the effectiveness of regulatory strategies.

Overview of important design issues for a National Human Exposure Assessment Survey

Exposure issues have important consequences for regulatory decisions. Reliable answers to exposure questions are critical for site cleanup, model validation, and cumulative risk issues, as well as giving perspective on our risk estimates. This paper discusses some of the important issues in designing the National Human Exposure Assessment Survey (NHEXAS) and, by implication, other exposure-monitoring-based studies as well. Sampling design issues are discussed in terms useful to exposure assessors. These issues include simple random sample designs versus more complex multistage designs, design efficiency, how to determine the sample size for the desired precision of the estimate, and the effects of stratification and oversampling on the needed sample size. This paper also discusses several important nonsampling issues such as population definition, response rates, and several potential sources of error in interpreting the monitoring results.

The importance of human exposure information: a need for exposure-related data bases to protect and promote public health

As a subfield of public health, environmental health is concerned with evaluating and ameliorating the effects of people on the environment and the effects of the environment on people. Separating hazards from risks, and characterizing the magnitude, likelihood, and uncertainty of risks is at the heart of environmental health in the 1990s. To this end, a full range of data is needed, including data that characterize the distribution of hazards, the population potentially at risk, and the contact between people and pollution that creates the risk. Several government-sponsored data systems contain information on a range of exposure estimators. The challenge is to develop meaningful, properly validated models to identify public health needs and evaluate public health programs.

Estimating exposure and dose to characterize health risks: the role of human tissue monitoring in exposure assessment

Exposure assessment is an integral part of health risk characterization. Exposure assessments typically address three critical aspects of exposure: the number of people exposed to the environmental toxicant, at specific concentrations, for the time period of interest; the resulting dose; and the relative contribution of important sources and pathways to exposure/dose. Because historically both "point-of-contact" measurements and information about dose and related pharmacokinetic processes have been lacking, exposure assessments have had to rely on construction of "scenarios" to estimate exposure and dose. This could change, however, as advances in development of biologic markers of exposure and dose make it possible to measure and interpret toxicant concentrations in accessible human tissues. The increasing availability of "biomarkers," coupled with improvements in pharmacokinetic understanding, present opportunities to estimate ("reconstruct") exposure from measurements of dose and knowledge of intake and uptake parameters. Human tissue monitoring, however, is not a substitute for more traditional methods of measuring exposure, but rather a complementary approach. A combination of exposure measurements and dose measurements provides the most credible scientific basis for exposure assessment.