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Biomedical subjects

K Sexton

Publications and source records attributed to K Sexton.

At least 37 records · Page 2Linked to original sources
PubMed1990

The federal environmental health workforce in the United States.

This paper summarizes existing data on the size and composition of the federal environmental health workforce, delineates the major categories of activities carried out by its members, identifies current and emerging issues that are likely to affect workforce activities, and makes qualitative inferences about future trends and directions. Findings suggest that there is a current and future need for more and better qualified professionals in the federal environmental health workforce.

Environmental Health↗
PubMed1983

Indoor air pollution: a public health perspective.

Although official efforts to control air pollution have traditionally focused on outdoor air, it is now apparent that elevated contaminant concentrations are common inside some private and public buildings. Concerns about potential public health problems due to indoor air pollution are based on evidence that urban residents typically spend more than 90 percent of their time indoors, concentrations of some contaminants are higher indoors than outdoors, and for some pollutants personal exposures are not characterized adequately by outdoor measurements. Among the more important indoor contaminants associated with health or irritation effects are passive tobacco smoke, radon decay products, carbon monoxide, nitrogen dioxide, formaldehyde, asbestos fibers, microorganisms, and aeroallergens. Efforts to assess health risks associated with indoor air pollution are limited by insufficient information about the number of people exposed, the pattern and severity of exposures, and the health consequences of exposures. An overall strategy should be developed to investigate indoor exposures, health effects, control options, and public policy alternatives.

Adolescent↗
PubMed1983

Estimating human exposure to nitrogen dioxide: an indoor/outdoor modeling approach.

Adverse health consequences associated with human exposure to nitrogen dioxide are well documented. In order for policymakers to assess health risks and implement appropriate control strategies, accurate information is required concerning (1) the number of people exposed, (2) the severity and patterns of exposure, and (3) the health-related effects of exposure. In the past, data from central monitoring sites have been used to establish air pollution exposures. However, it is now recognized that people spend much of their time indoors or in areas away from fixed monitors where pollutant concentrations may be drastically different. An attempt to provide a more realistic estimate of nitrogen dioxide exposures is made. A simple deterministic model is developed, relating exposure to background ambient levels, indoor values, and human activities. Ambient and indoor parameters are derived from monitoring programs in six U.S. cities. Results suggest indoor nitrogen dioxide concentrations in private dwellings vary primarily with outdoor levels and type of cooking fuel, but are also affected by factors such as air-exchange rates and strength of indoor sources. Estimates of population exposures are obtained by combining observed distributions of nitrogen dioxide concentrations from outdoor and indoor settings with information about number of people and time spent in each microenvironment.

Air Pollution↗
PubMed1979

Glycohemoglobin and glucose tolerance tests compared as indicators of borderline diabetes.

We concurrently measured glycohemoglobin and performed 3-h oral (100 g) glucose tolerance tests on 69 ambulatory patients suspected of having abnormal carbohydrate metabolism. The patients were divided into two groups: (a) The 37 patients for whom the results were normal had plasma glucose concentrations of 0.70--1.15 milligram during fasting and 0.70--1.23 g/L 2 h after glucose ingestion. (b) Borderline diabetics exceeded one or both of these limits. The range of glycohemoglobin in the normal group was 3.0--4.7% of total hemoglobin. Of the 21 borderline diabetics, 11 had increased glycohemoglobin (4.8--8.0%). The difference in tolerance test results between borderline diabetics with and without increased glycohemoglobin was insufficient to predict the status of glycohemoglobin. We suggest a tentative definition for latent diabetes: increased glycohemoglobin in the presence of normal or borderline-abnormal glucose concentration in plasma collected during fasting.

Adolescent↗
PubMed1975

The effect of triazolam on the sleep of insomniacs.

The effects of three oral doses of bedtime triazolam (0.25 mg, 0.5 mg, and 1.0 mg) a new benzodiazepine, on the laboratory sleep of insomniacs were studied in a double blind design which used the following 14 consecutive night schedule: 1-4 placebo; 5-11 drug; 12-14 placebo. Effects on sleep were measured objectively by conventional EEG/EOG/EMG sleep recordings and subjectively by questionnaires administered each morning. Side or toxic effects were assessed by screening physicals and questionnaires administered each morning and each evening and by a comparison of the prestudy vs. end-study physical exams and clinical lab tests. At the 0.5 mg dose triazolam significantly reduced several objective and subjective measures of insomnia. It had lesser effects at the 0.25 mg dose and equal or greater effects at 1.0 mg dose. There were no remarkable side or toxic effects at any dose.

Adult↗
PubMedDate not supplied

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.

Environmental Health↗
PubMedDate not supplied

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.

Environmental Health↗
PubMedDate not supplied

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.

Black or African American↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

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).

Biomarkers↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

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.

Adolescent↗
PubMedDate not supplied

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.

Air Pollution, Indoor↗