The Contribution of Declines in Blood Lead Levels to Reductions in Blood Pressure Levels: Longitudinal Evidence in the Strong Heart Family Study.

BACKGROUND: Chronic lead exposure is associated with both subclinical and clinical cardiovascular disease. We evaluated whether declines in blood lead were associated with changes in systolic and diastolic blood pressure in adult American Indian participants from the SHFS (Strong Heart Family Study). METHODS AND RESULTS: Lead in whole blood was measured in 285 SHFS participants in 1997 to 1999 and 2006 to 2009. Blood pressure and measures of cardiac geometry and function were obtained in 2001 to 2003 and 2006 to 2009. We used generalized estimating equations to evaluate the association of declines in blood lead with changes in blood pressure; cardiac function and geometry measures were considered secondary. Mean blood lead was 2.04 µg/dL at baseline. After ≈10 years, mean decline in blood lead was 0.67 µg/dL. In fully adjusted models, the mean difference in systolic blood pressure comparing the highest to lowest tertile of decline (>0.91 versus <0.27 µg/dL) in blood lead was -7.08 mm Hg (95% CI, -13.16 to -1.00). A significant nonlinear association between declines in blood lead and declines in systolic blood pressure was detected, with significant linear associations where blood lead decline was 0.1 µg/dL or higher. Declines in blood lead were nonsignificantly associated with declines in diastolic blood pressure and significantly associated with declines in interventricular septum thickness. CONCLUSIONS: Declines in blood lead levels in American Indian adults, even when small (0.1-1.0 µg/dL), were associated with reductions in systolic blood pressure. These findings suggest the need to further study the cardiovascular impacts of reducing lead exposures and the importance of lead exposure prevention.

Blood cadmium, lead, manganese, mercury, and selenium levels in American Indian populations: The Strong Heart Study.

BACKGROUND: Many American Indian (AI) communities are in areas affected by environmental contamination, such as toxic metals. However, studies assessing exposures in AI communities are limited. We measured blood metals in AI communities to assess historical exposure and identify participant characteristics associated with these levels in the Strong Heart Study (SHS) cohort. METHOD: Archived blood specimens collected from participants (n = 2014, all participants were 50 years of age and older) in Arizona, Oklahoma, and North and South Dakota during SHS Phase-III (1998-1999) were analyzed for cadmium, lead, manganese, mercury, and selenium using inductively coupled plasma triple quadrupole mass spectrometry. We conducted descriptive analyses for the entire cohort and stratified by selected subgroups, including selected demographics, health behaviors, income, waist circumference, and body mass index. Bivariate associations were conducted to examine associations between blood metal levels and selected socio-demographic and behavioral covariates. Finally, multivariate regression models were used to assess the best model fit that predicted blood metal levels. FINDINGS: All elements were detected in 100% of study participants, with the exception of mercury (detected in 73% of participants). The SHS population had higher levels of blood cadmium and manganese than the general U.S. population 50 years and older. The median blood mercury in the SHS cohort was at about 30% of the U.S. reference population, potentially due to low fish consumption. Participants in North Dakota and South Dakota had the highest blood cadmium, lead, manganese, and selenium, and the lowest total mercury levels, even after adjusting for covariates. In addition, each of the blood metals was associated with selected demographic, behavioral, income, and/or weight-related factors in multivariate models. These findings will help guide the tribes to develop education, outreach, and strategies to reduce harmful exposures and increase beneficial nutrient intake in these AI communities.

Associations between select blood VOCs and hematological measures in NHANES 2005-2010.

Exposure to VOCs is linked to health effects ranging from asthma to cancer and to negative impacts on the hematopoietic system. We examined the association between select blood VOC concentrations and hematological measures in a representative sample of the U.S. population from NHANES cycles spanning the years 2005 to 2010. We used Cox regression to assess the association between complete blood count with five-part differential (CBC) parameters and seven select blood VOCs, while addressing low detection rates among VOCs. Tobacco smoke exposure was classified using serum cotinine levels. The not-smoke-exposed group had lower VOC levels for most analytes compared with the smoke-exposed. Correlations between benzene, toluene, ethylbenzene, and xylenes (BTEX) were moderate to strong. Statistical associations were found between benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS) and hematocrit, hemoglobin, and white blood cell count among the smoke-exposed. Among the not-smoke-exposed, there was an association between BTEX and platelet count. We considered benzene most likely to be associated with higher levels of CBC concentrations. Our findings suggest VOC levels currently found in the general U.S. population are associated with changes in hematological measures, and smoking could be a contributor.

Adverse Childhood Experiences and Adulthood Negotiation in Intimate Partner Violence: The Sequentially Paradoxical Role of Interpersonal Sensitivity Among Female Inmates.

The present study examined interpersonal sensitivity and hostility as separate and sequential mediators in the association between adverse childhood experiences (ACE) and the conflict tactic of negotiation (e.g., a strategy utilized to resolve conflict with a romantic partner) among female inmates. Participants were 258 female inmates recruited from three Southern California jails. After statistically controlling for partner-negotiation, results from a sequential mediation model revealed that the association between ACE and negotiation was mediated through three separate pathways. The first single mediational pathway indicated that ACE was positively associated with interpersonal sensitivity, which in turn had a positive association with negotiation. The second single mediational pathway revealed that ACE was positively associated with hostility, which in turn had a negative association with negotiation. Finally, the sequential meditational path revealed that interpersonal sensitivity through hostility mediated the ACE and negotiation relationship. The present results suggest that ACE may result in increased interpersonal sensitivity, which may paradoxically result in both more and less negotiation with romantic partners. That is, ACE through interpersonal sensitivity alone may result in more negotiation, and ACE through interpersonal sensitivity and then hostility may result in less negotiation with romantic partners. We explicate how the psychopathological construct of interpersonal sensitivity may lead to increased and decreased rates of the positively construed conflict tacit of negotiation. In addition, the present findings are discussed in light of the high rates of both revictimization and perpetration of violence among female inmates.

Characterization of trace elements exposure in pregnant women in the United States, NHANES 1999-2016.

OBJECTIVE: The objective of the current study is to report on urine, blood and serum metal concentrations to characterize exposures to trace elements and micronutrient levels in both pregnant women and women of child-bearing age in the U.S. National Health and Nutrition Examination Survey (NHANES) years 1999-2016. METHODS: Urine and blood samples taken from NHANES participants were analyzed for thirteen urine metals, three blood metals, three serum metals, speciated mercury in blood and speciated arsenic in urine. Adjusted and unadjusted least squares geometric means and 95% confidence intervals were calculated for all participants among women aged 15-44 years. Changes in exposure levels over time were also examined. Serum cotinine levels were used to adjust for smoke exposure, as smoking is a source of metal exposure. RESULTS: Detection rates for four urine metals from the ATSDR Substance Priority List: arsenic, lead, mercury and cadmium were ~83-99% for both pregnant and non-pregnant women of child bearing age. A majority of metal concentrations were higher in pregnant women compared to non-pregnant women. Pregnant women had higher mean urine total arsenic, urine mercury, and urine lead; however, blood lead and mercury were higher in non-pregnant women. Blood lead, cadmium, mercury, as well as urine antimony, cadmium and lead in women of childbearing age decreased over time, while urine cobalt increased over time. CONCLUSIONS: Pregnant women in the US have been exposed to several trace metals, with observed concentrations for some trace elements decreasing since 1999.

Exposure of dioxin-like chemicals in participants of the Anniston community health survey follow-up.

The 2014 follow-up of the Anniston Community Health Survey (ACHS II) consisted of 338 surviving participants from the 2005-2007 baseline study (ACHS) who had previous polychlorinated biphenyl (PCB) measurements, were not pregnant, and were not institutionalized. Questionnaires and blood samples provided the demographic, personal history, and chemical concentration data of the Anniston residents. Approximately 51% of participants were African American, 72% were female, and the mean age was 63 years old. The objectives of this study were to provide an exposure assessment of dioxin-like chemicals in the ACHS II participants and compare the measurements with the general United States (U.S.) population via the National Health and Nutrition Examination Survey (NHANES). Stratified analyses revealed significantly higher average total dioxin toxic equivalencies (TEQs) among African Americans compared to Whites (33.1 vs. 19.2 pg/g lipid), and in females compared to males (29.8 vs. 17.0 pg/g lipid). When adjusting for age, sex, and race in linear regression, we found ACHS II participants to have significantly higher total dioxin TEQ than the general 2014 U.S. population that we estimated for using half-life and NHANES 2003/04 data (most recent NHANES individual samples data), by 16.7 pg/g lipid. Principal component analyses showed that non-ortho and mono-ortho PCBs were separated from the other dioxin-like chemicals among the Anniston residents, whereas the chemicals were all clustered together for estimated NHANES 2014. The concentrations of dioxin-like chemicals, especially non-ortho and mono-ortho PCBs, in Anniston residents who resided near the former PCB production plant were higher than those in the general U.S. POPULATION: Although data strongly supported this difference, these inferences are limited because NHANES 2013/14 data were unavailable and we used estimated NHANES 2014 levels that we imputed from NHANES 2003/04 data in conjunction with half-life values estimated from Milbrath et al., 2009.

Prevalence and associated demographic characteristics of exposure to multiple metals and their species in human populations: The United States NHANES, 2007-2012.

Lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As) are among the top 10 pollutants of global health concern. Studies have shown that exposures to these metals produce severe adverse effects. However, the mechanisms underlying these effects, particularly joint toxicities, are poorly understood in humans. The objective of this investigation was to identify and characterize prevalent combinations of these metals and their species in the U.S. NHANES population to provide background data for future studies of potential metal interactions. Exposure was defined as urine or blood levels ≥ medians of the NHANES 2007-2012 participants ≥6 years (n = 7408). Adjusted-odds ratios (adj-OR) and 95% confidence intervals were determined for covariates (age, gender, and race/ethnicity, cotinine and body mass index). Species-specific analysis was also conducted for As and Hg including iAs (urinary arsenous acid and/or arsenic acid), met-iAs (urinary monomethylarsonic acid and/or dimethylarsinic acid), and oHg (blood methyl-mercury and/or ethyl-mercury). For combinations of As and Hg species, age- and gender-specific prevalence was determined among NHANES 2011-2012 participants (n = 2342). Data showed that approximately 49.3% of the population contained a combination of three or more metals. The most prevalent unique specific combinations were Pb/Cd/Hg/As, Pb/Cd/Hg, and Pb/Cd. Age was consistently associated with these combinations: adj-ORs ranged from 10.9 (Pb/Cd) to 11.2 (Pb/Cd/Hg/As). Race/ethnicity was significant for Pb/Cd/Hg/As. Among women of reproductive age, frequency of oHg/iAs/met-iAS and oHg/met-iAs was 22.9 and 40.3%, respectively. These findings may help prioritize efforts to assess joint toxicities and their impact on public health.

Mortality from asbestos-associated disease in Libby, Montana 1979-2011.

Research on asbestos exposure in Libby, MT, has focused on occupational exposure in vermiculite mining and processing, but less attention has been paid to asbestos-related mortality among community members without vermiculite mining occupational history. Our study reports on asbestos-related mortality in Libby over 33 years (1979-2011) while controlling for occupational exposure. We calculated sex-specific 33-year standardized mortality ratios (SMRs) for Libby residents who died from 1979 to 2011 with an asbestos-related cause of death. Decedent address at time of death was geocoded to confirm inclusion in the Libby County Division. We controlled for past W.R. Grace employment by including and then removing them from the SMR analysis. Six hundred and ninety-four decedents were identified as having at least one asbestos-related cause of death and residing in our study area boundary. Statistically significant (P<0.05) 33-year SMRs, both before and after controlling for W.R. Grace employment, were found for: male and female non-malignant respiratory diseases, female COPD, and asbestosis for both sexes combined. Eighty-five men and two women were matched to employment records. We observed elevated asbestos-related mortality rates among males and females. SMR results for asbestosis were high for both sexes, even after controlling for past W.R. Grace employment. These results suggest that the general population may be experiencing asbestos-related effects, not just former vermiculite workers. Additional research is needed to determine whether SMRs remain elevated after controlling for secondary exposure, such as living with vermiculite workers.

Biomonitoring Human Exposure to Household Air Pollution and Association with Self-reported Health Symptoms - A Stove Intervention Study in Peru.

BACKGROUND: Household air pollution (HAP) from indoor biomass stoves contains harmful pollutants, such as polycyclic aromatic hydrocarbons (PAHs), and is a leading risk factor for global disease burden. We used biomonitoring to assess HAP exposure and association with self-reported symptoms in 334 non-smoking Peruvian women to evaluate the efficacy of a stove intervention program. METHODS: We conducted a cross-sectional study within the framework of a community randomized control trial. Using urinary PAH metabolites (OH-PAHs) as the exposure biomarkers, we investigated whether the intervention group (n=155, with new chimney-equipped stoves) were less exposed to HAP compared to the control group (n=179, with mostly open-fire stoves). We also estimated associations between the exposure biomarkers, risk factors, and self-reported health symptoms, such as recent eye conditions, respiratory conditions, and headache. RESULTS: We observed reduced headache and ocular symptoms in the intervention group than the control group. Urinary 2-naphthol, a suggested biomarker for inhalation PAH exposure, was significantly lower in the intervention group (GM with 95% CI: 13.4 [12.3, 14.6] µg/g creatinine) compared to control group (16.5 [15.0, 18.0] µg/g creatinine). Stove type and/or 2-naphthol was associated with a number of self-reported symptoms, such as red eye (adjusted OR with 95% CI: 3.80 [1.32, 10.9]) in the past 48h. CONCLUSIONS: Even with the improved stoves, the biomarker concentrations in this study far exceeded those of the general populations and were higher than a no-observed-genotoxic-effect-level, indicating high exposure and a potential for increased cancer risk in the population.

Sleep patterns in children with and without autism spectrum disorders: developmental comparisons.

The present study examined age-related changes in the sleep of children with autism spectrum disorders (ASD) compared to age-related changes in the sleep of typically developing (TD) children. Participants were 108 mothers of children with ASD and 108 mothers of TD children. Participants completed a questionnaire on children's overall sleep quality that also tapped specific sleep-domains (i.e., bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night wakings, parasomnias, disordered breathing, daytime sleepiness). Results confirm significantly poorer sleep quantity and quality in children with ASD, particularly children age 6-9 years. Unlike TD children, the sleep problems of children with ASD were unlikely to diminish with age. Our findings suggest that it is important to exam specific domains of sleep as well as overall sleep patterns. Finding of significant age-related interactions suggests that the practice of combining children from wide age-ranges into a single category obfuscates potentially important developmental differences.

Comparison of blood volatile organic compound levels in residents of Calcasieu and Lafayette Parishes, LA, with US reference ranges.

Agency for Toxic Substances and Disease Registry conducted a study to evaluate body burden levels of volatile organic compounds (VOCs) among residents of highly industrialized Calcasieu Parish, LA, USA, in 2002. Blood VOC levels in a representative sample of participants in Calcasieu Parish were compared with a similar group of participants in the less-industrialized Lafayette Parish. Participants' ages ranged from 15 to 91 years, 46% were men, and 89% were Caucasian. VOC levels in these two populations were also compared at the national levels. Solid-phase microextraction coupled with gas chromatography mass spectrometry was used to measure levels of 30 VOCs in blood samples collected from 283 self-described non-smoking study participants. Of the 30 VOCs, 6 had quantifiable levels in at least 25% of the blood samples analyzed. The frequency of detection was >95% for benzene and m-/p-xylene, >60% for 1,4-dichlorbenzene and toluene, 27% for ethylbenzene, and 39% for styrene. Calcasieu and Lafayette Parish participants had similar distributions for six VOCs in key percentiles and geometric means. When compared with a representative sampling of the 1999-2000 US general population, no significant differences were found between the parish data and the US general population.

Impact of body mass index on the detection of radiographic localized pleural thickening.

RATIONALE AND OBJECTIVES: Subpleural fat can be difficult to distinguish from localized pleural thickening (LPT), a marker of asbestos exposure, on chest radiographs. The aims of this study were to examine the influence of body mass index (BMI) on the performance of radiograph readers when classifying LPT and to model the risk of false test results with varying BMI. MATERIALS AND METHODS: Subjects (n = 200) were patients being screened or treated for asbestos-related health outcomes. A film chest radiograph, a digital chest radiograph, and a high-resolution computed tomography (HRCT) chest scan were collected from each subject. All radiographs were independently read by seven B readers and scored using the International Labour Office system. HRCT scans, read by three experienced thoracic radiologists, served as the gold standard for the presence of LPT. We calculated measures of radiograph reader performance, including sensitivity and specificity, for each image modality. We also used logistic regression to estimate the probability of a false-positive and a false-negative result while controlling for covariates. RESULTS: The proportion of false-positive readings correlated with BMI. While controlling for covariates, regression modeling showed the probability of a false-positive result increased with increasing BMI category, younger age, not having pleural calcification, and among subjects not reporting occupational or household contact asbestos exposure. CONCLUSIONS: Clinicians should be cautious when evaluating radiographs of younger obese persons for the presence of asbestos-related pleural plaque, particularly in populations having an anticipated low or background prevalence of LPT.

Predictors of stimulant abuse treatment outcomes in severely mentally ill outpatients.

BACKGROUND: Severe mental illness is often exclusionary criteria for studies examining factors that influence addiction treatment outcome. Therefore, little is known about predictors of treatment response of individuals receiving psychosocial treatments for addictions who suffer from co-occurring severe mental illness. METHODS: The impact of demographic, substance abuse severity, psychiatric severity, and service utilization variables on in-treatment performance (i.e., longest duration of abstinence) in a 12-week contingency management (CM) intervention for stimulant abuse in 96 severely mentally ill adults was investigated. A 4-step linear regression was used to identify independent predictors of in-treatment abstinence. RESULTS: This model accounted for 37.4% of variance in the longest duration of abstinence outcome. Lower levels of stimulant use (i.e., stimulant-negative urine test) and psychiatric severity (i.e., lower levels of psychiatric distress), as well as higher rates of outpatient treatment utilization at study entry were independently associated with longer duration of drug abstinence. CONCLUSION: These data suggest that individuals with low levels of stimulant use and psychiatric severity, as well as those actively engaged in services are most likely to succeed in a typical CM intervention. For others, modifications to CM interventions, such as increasing the value of reinforcement or adding CM to evidence based psychiatric interventions may improve treatment outcomes.

Associations between radiographic findings and spirometry in a community exposed to Libby amphibole.

BACKGROUND: Among asbestos-exposed individuals, abnormal spirometry is usually associated with parenchymal abnormalities or diffuse pleural thickening. Localised pleural thickening (LPT), the most common abnormality associated with asbestos exposure, is typically thought to be a marker of exposure with little clinical consequence. Our objective was to determine if abnormal spirometry is associated with LPT independent of other abnormalities, using data from community-based screening conducted in Libby, Montana. METHODS: Subjects were a subset of screening participants comprising persons with interpretable spirometry and chest radiograph results (n=6475). Chest radiographs were independently evaluated by two or three B readers, and participants were classified by mutually exclusive categories of spirometry outcome: normal, restriction, obstruction or mixed defect. RESULTS: Restrictive spirometry was strongly associated with parenchymal abnormalities (OR 2.9; 95% CI 1.4 to 6.0) and diffuse pleural thickening (OR 4.1; 95% CI 2.1 to 7.8). Controlling for the presence of these abnormalities as well as age, smoking status and other covariates, restrictive spirometry was also associated with LPT (OR 1.4; 95% CI 1.1 to 1.8). The risk of restrictive spirometric findings correlated with the severity of LPT. CONCLUSIONS: In this large community-based screening cohort, restrictive spirometry is significantly associated with LPT, indicating that this abnormality may result in lung function impairment. Physicians treating patients exposed to Libby amphibole should be aware that LPT may have functional consequences.

Lessons from the 2006 Louisiana health and population survey.

The 2005 hurricane season caused extensive damage and induced a mass migration of approximately 1.1 million people from southern Louisiana in the United States. Current and accurate estimates of population size and demographics and an assessment of the critical needs for public services were required to guide recovery efforts. Since forecasts using pre-hurricane data may produce inaccurate estimates of the post-hurricane population, a household survey in 18 hurricane-affected parishes was conducted to provide timely and credible information on the size of these populations, their demographics and their condition. This paper describes the methods used, the challenges encountered, and the key factors for successful implementation. This post-disaster survey was unique because it identified the needs of the people in the affected parishes and quantified the number of people with these needs. Consequently, this survey established new population and health indicator baselines that otherwise would have not been available to guide the relief and recovery efforts in southern Louisiana.

Variability of urinary concentrations of polycyclic aromatic hydrocarbon metabolite in general population and comparison of spot, first-morning, and 24-h void sampling.

Urinary mono-hydroxy polycyclic aromatic hydrocarbons (OH-PAHs) are commonly used in biomonitoring to assess exposure to polycyclic aromatic hydrocarbons (PAHs). Similar to other biologically non-persistent chemicals, OH-PAHs have relatively short biological half-lives (4.4-35 h). Little information is available on their variability in urinary concentrations over time in non-occupationally exposed subjects. This study was designed to (i) examine the variability of nine urinary OH-PAH metabolite concentrations over time and (ii) calculate sample size requirements for future epidemiological studies on the basis of spot urine, first-morning void, and 24-h void sampling. Individual urine samples (n=427) were collected during 1 week from 8 non-occupationally exposed adults. We recorded the time and volume of each urine excretion, dietary details, and driving activities of the participants. Within subjects, the coefficients of variation (CVs) for the wet-weight concentration of OH-PAHs in all samples ranged from 45% to 297%; creatinine adjustment reduced the CV to 19-288% (P<0.001; paired t-test). The simulated 24-h void concentrations were the least variable measure, with CVs ranging from 13% to 182% for the 9 OH-PAHs. Within-day variability contributed on average 84%, and between-day variability accounted for 16% of the total variance of 1-hydroxypyrene (1-PYR). Intraclass correlation coefficients of 1-PYR levels were 0.55 for spot urine samples, 0.65 [corrected] for first-morning voids, and 0.77 [corrected] for 24-h voids, indicating a high degree of correlation between urine measurements collected from the same subject over time. Sample size calculations were performed to estimate the number of subjects required for detecting differences in the geometric mean at a statistical power of 80% for spot urine, first-morning, and 24-h void sampling. These data will aid in the design of future studies of PAHs and possibly other biologically non-persistent chemicals and in the interpretation of their analytical results.

Assessment of non-occupational exposure to polycyclic aromatic hydrocarbons through personal air sampling and urinary biomonitoring.

Non-occupational inhalation and ingestion exposure to polycyclic aromatic hydrocarbons (PAHs) has been studied in 8 non-smoking volunteers through personal air sampling and urinary biomonitoring. The study period was divided into 4 segments (2 days/segment), including weekdays with regular commute and weekends with limited traffic related exposures; each segment had a high or low PAH diet. Personal air samples were collected continuously from the subjects while at home, at work, and while commuting to and from work. All urine excretions were collected as individual samples during the study. In personal air samples, 28 PAHs were measured, and in urine samples 9 mono-hydroxylated metabolites (OH-PAHs) from 4 parent PAHs (naphthalene, fluorene, phenanthrene and pyrene) were measured. Naphthalene was found at higher concentrations in air samples collected at the subjects' residences, whereas PAHs with four or more aromatic rings were found at higher levels in samples taken while commuting. Urinary OH-PAH biomarker levels increased following reported high inhalation and/or dietary exposure. On days with a low PAH diet, the total amount of inhaled naphthalene during each 24-hour period was well correlated with the amount of excreted naphthols, as was, to a lesser extent, fluorene with its urinary metabolites. During days with a high dietary intake, only naphthalene was significantly correlated with its excreted metabolite. These findings suggest that this group of non-occupational subjects were exposed to naphthalene primarily through indoor air inhalation, and exposed to other PAHs such as pyrene mainly through ingestion.

The usefulness of computed tomography in detecting asbestos-related pleural abnormalities in people who had indeterminate chest radiographs: the Libby, MT, experience.

This epidemiological study was conducted to determine whether high-resolution computed tomography (HRCT) is useful to screen for pulmonary abnormalities in people exposed to vermiculite containing asbestos. During June-September 2001, we evaluated HRCT of 353 people in Libby, MT, who had been exposed to asbestiform minerals associated with vermiculite. Of these, 334 participants of the summer 2000 medical testing program underwent HRCT of the chest at St. John's Lutheran Hospital and 19 eligible people who recently had undergone an HRCT scan at the same facility and under the same testing protocol allowed the study reviewers to use that scan. All 353 study participants were former vermiculite mine/mill workers (n = 55), their household contacts (n = 99), and people exposed to vermiculite through recreational or other activities (n = 199). Participants' 2000 medical testing results indicated only one of the three B-reader chest radiograph reviewers had reported a pleural abnormality (indeterminate chest radiograph). Three expert computer tomography (CT) scan evaluators reviewed the HRCT scans and identified pleural abnormalities in 98 (27.8%) of the 353 participants whose previous chest radiographs were classified indeterminate. Of these 98 people, 69 (70.4%) were either former vermiculite mine/mill workers or household contacts, and 40 (40.8%) showed pleural calcification on HRCT. Thirty out of the 40 people with pleural calcification reported having no occupational exposure to either Libby vermiculite or asbestos. Our findings indicate that low-dose HRCT can be considered for screening certain former vermiculite mine/mill workers and their household contacts who have indeterminate chest radiographs and may be useful for diagnosing a suspicious finding on a chest radiograph, particularly in a high-risk person.

Neurobehavioral evaluation for a community with chronic exposure to hydrogen sulfide gas.

In May 2000, the Agency for Toxic Substances and Disease Registry of the US government conducted a health investigation in response to community concerns regarding ambient and indoor hydrogen sulfide (H(2)S), odor, and health symptoms in Dakota City, Nebraska. The objective was to determine whether adult residents in an area with repeated exposure to H(2)S showed poorer performance on neurobehavioral tests than unexposed residents. Study participants were required to meet age (#10878;16 years of age) and length of residency (2 years) eligibility requirements. A battery of computer-assisted standardized neurobehavioral tests was administered in English or Spanish. A questionnaire was used to collect information about participants, demographic and health status. Three hundred forty-five people agreed to participate. After the exclusion of 10 persons, analyses were conducted on 335 participants; 171 residents in the target area and 164 residents in the comparison area. The two groups were comparable in demographic characteristics and various health conditions. Overall, neurobehavioral test results for the target and comparison groups were similar. Residence in the H(2)S-exposed area was associated with marginally poorer performance on a test of memory, namely, match to sample score, and a test of grip strength. However, these differences were not significant. Deficits in overall neurobehavioral performance were not associated with exposure to H(2)S in this study.