An evaluation of a Lake Houston tributary, Cypress Creek, for contamination and water quality

Introduction. Lake Houston serves as a reservoir for both recreational and drinking water for residents of Houston, Texas, and the metropolitan area. The Texas Commission on Environmental Quality (TCEQ) expressed concerns about the water quality and increasing amounts of pathogenic bacteria in Lake Houston (3). The objective of this investigation is to evaluate water quality for the presence of bacteria, nitrates, nitrites, carbon, phosphorus, dissolved oxygen, pH, turbidity, suspended solids, dissolved solids, and chlorine in Cypress Creek. The aims of this project are to analyze samples of water from Cypress Creek and to render a quantitative and graphical representation of the results. The collected information will allow for a better understanding of the aqueous environment in Cypress Creek.^ Methods. Water samples were collected in August 2009 and analyzed in the field and at UTSPH laboratory by spectrophotometry and other methods. Mapping software was utilized to develop novel maps of the sample sites using coordinates attained with the Global Positioning System (GPS). Sample sites and concentrations were mapped using Geographic Information System (GIS) software and correlated with permitted outfalls and other land use characteristic.^ Results. All areas sampled were positive for the presence of total coliform and Escherichia coli (E. coli). The presences of other water contaminants varied at each location in Cypress Creek but were under the maximum allowable limits designated by the Texas Commission on Environmental Quality. However, dissolved oxygen concentrations were elevated above the TCEQ limit of 5.0 mg/L at majority of the sites. One site had near-limit concentration of nitrates at 9.8 mg/L. Land use above this site included farm land, agricultural land, golf course, parks, residential neighborhoods, and nine permitted TCEQ effluent discharge sites within 0.5 miles upstream.^ Significance. Lake Houston and its tributary, Cypress Creek, are used as recreational waters where individuals may become exposed to microbial contamination. Lake Houston also is the source of drinking water for much of Houston/Harris and Galveston Counties. This research identified the presence of microbial contaminates in Cypress Creek above TCEQ regulatory requirements. Other water quality variables measured were in line with TCEQ regulations except for near-limit for nitrate at sample site #10, at Jarvis and Timberlake in Cypress Texas.^

Industrial benzene emissions in Houston: Legal barriers to reducing a public health threat

Decades of research show that environmental exposure to the chemical benzene is associated with severe carcinogenic, hematoxic and genotoxic effects on the human body. As such, the Environmental Protection Agency (EPA) has designated the chemical as a Hazardous Air Pollutant and prescribed benzene air concentration guidelines that provide cities with an ideal ambient level to protect human health. However, in Houston, Texas, a city home to the top industrial benzene emitters in the US who undoubtedly contribute greatly to the potentially unsafe levels of ambient benzene, regulations beyond the EPA’s unenforceable guidelines are critical to protecting public health. Despite this, the EPA has failed to establish National Ambient Air Quality Standards (NAAQS) for benzene. States are thus left to regulate air benzene levels on their own; in the case of Texas, the Texas Commission on Environmental Quality (TCEQ) and state legislature have failed to proactively develop legally enforceable policies to reduce major source benzene emissions. This inaction continues to exacerbate a public health problem, which may only be solved through a legal framework that restricts preventable benzene emissions to protect human health and holds industrial companies accountable for violations of such regulations and standards. This analysis explores legal barriers that the City of Houston and other relevant agencies currently face in their attempt to demand and bring about such change. ^

The role of municipalities in air toxics regulation: The Houston experience

The federal regulatory regime for addressing airborne toxic pollutants functions fairly well in most of the country. However, it has proved deficient in addressing local risk issues, especially in urban areas with densely concentrated sources. The problem is especially pronounced in Houston, which is home to one of the world's biggest petrochemical complexes and a major port, both located near a large metropolitan center. Despite the fact that local government's role in regulating air toxics is typically quite limited, from 2004-2009, the City of Houston implemented a novel municipality-based air toxics reduction strategy. The initiatives ranged from voluntary agreements to litigation and legislation. This case study considers why the city chose the policy tools it did, how the tools performed relative to the designers' intentions, and how the debate among actors with conflicting values and goals shaped the policy landscape. The city's unconventional approach to controlling hazardous air pollution has not yet been examined rigorously. The case study was developed through reviews of publicly available documents and quasi-public documents obtained through public record requests, as well as interviews with key informants. The informants represented a range of experience and perspectives. They included current and former public officials at the city (including Mayor White), former Texas Commission on Environmental Quality staff, faculty at local universities, industry representatives, and environmental public health advocates. Some of the city's tools were successful in meeting their designers' intent, some were less successful. Ultimately, even those tools that did not achieve their stated purpose were nonetheless successful in bringing attention and resources to the air quality issue. Through a series of pleas and prods, the city managed to draw attention to the problem locally and get reluctant policymakers at higher levels of government to respond. This work demonstrates the potential for local government to overcome limitations in the federal regulatory regime for air toxics control, shifting the balance of local, state, and federal initiative. It also highlights the importance of flexible, cooperative strategies in local environmental protection.^

Airliner cabin air quality exposure assessment

The airliner cabin environment and its effects on occupant health have not been fully characterized. This dissertation is: (1) A review of airliner environmental control systems (ECSs) that modulate the ventilation, temperature, relative humidity (RH), and barometric pressure (PB) of the cabin environment---variables related to occupant comfort and health. (2) A review and assessment of the methods and findings of key cabin air quality (CAQ) investigations. Several significant deficiencies impede the drawing of inferences about CAQ, e.g., lack of detail about investigative methods, differences in methods between investigations, limited assessment of CAQ variables, small sample sizes, and technological deficiencies of data collection. (3) A comprehensive evaluation of the methods used in the subsequent NIOSH-FAA Airliner CAQ Exposure Assessment Feasibility Study (STUDY) in which this author participated. A number of problems were identified which limit the usefulness of the data. (4) An analysis of the reliable 10-flight STUDY data. Univariate and multivariate methods applied to CO2 (a surrogate for air contaminants), temperature, RH, and PB, in association with percent passenger load, ventilation system, flight duration, airliner body type, and measurement location within the cabin, revealed neither the measured values nor their variability exceeded established health-based exposure limits. Regression analyses suggest CO2, temperature, and RH were affected by percent passenger load. In-flight measurements of CO2 and RH were relatively independent of ventilation system type or flight duration. Cabin temperature was associated with percent passenger load, ventilation system type, and flight duration. (5) A synthesis of the implications of the airliner ECS and cabin O2 environment on occupant health. A model was developed to predict consequences of the airliner cabin pressure altitude 8,000 ft limit and resulting model-estimated PO2 on cardiopulmonary status. Based on the PB, altitude, and environmental data derived from the 10 STUDY flights, the predicted PaO2 of adults with COPD, or elderly adults with or without COPD, breathing ambient cabin air could be < 55 mm Hg (SaO2 < 88%). Reduction in cabin PB found in the STUDY flights could aggravate various medical conditions and require the use of in-flight supplemental O2. ^

Revising the National Ambient Air Quality Standards: The integration of science and policy

Under the Clean Air Act, Congress granted discretionary decision making authority to the Administrator of the Environmental Protection Agency (EPA). This discretionary authority involves setting standards to protect the public's health with an "adequate margin of safety" based on current scientific knowledge. The Administrator of the EPA is usually not a scientist, and for the National Ambient Air Quality Standard (NAAQS) for particulate matter (PM), the Administrator faced the task of revising a standard when several scientific factors were ambiguous. These factors included: (1) no identifiable threshold below which health effects are not manifested, (2) no biological basis to explain the reported associations between particulate matter and adverse health effects, and (3) no consensus among the members of the Clean Air Scientific Advisory Committee (CASAC) as to what an appropriate PM indicator, averaging period, or value would be for the revised standard. ^ This project recommends and demonstrates a tool, integrated assessment (IA), to aid the Administrator in making a public health policy decision in the face of ambiguous scientific factors. IA is an interdisciplinary approach to decision making that has been used to deal with complex issues involving many uncertainties, particularly climate change analyses. Two IA approaches are presented; a rough set analysis by which the expertise of CASAC members can be better utilized, and a flag model for incorporating the views of stakeholders into the standard setting process. ^ The rough set analysis can describe minimal and maximal conditions about the current science pertaining to PM and health effects. Similarly, a flag model can evaluate agreement or lack of agreement by various stakeholder groups to the proposed standard in the PM review process. ^ The use of these IA tools will enable the Administrator to (1) complete the NAAQS review in a manner that is in closer compliance with the Clean Air Act, (2) expand the input from CASAC, (3) take into consideration the views of the stakeholders, and (4) retain discretionary decision making authority. ^

The relationship between enterotoxigenic {\it Escherichia coli\/} infection and environmental risk factors in Bilbeis, Egypt, 1981--1983

Diarrheal disease associated with enterotoxigenic Escherichia coli (ETEC) infection is one of the major public health problems in many developing countries, especially in infants and young children. Because tests suitable for field laboratories have been developed only relatively recently, the literature on the environmental risk factors associated with ETEC is not as complete as for many other pathogens or for diarrhea of unspecified etiology.^ Data from a diarrheal disease surveillance project in rural Egypt in which stool samples were tested for a variety of pathogens, and in which an environmental questionnaire was completed for the same study households, provided an opportunity to test for an association between ETEC and various risk factors present in those households. ETEC laboratory-positive specimens were compared with ETEC laboratory-negative specimens for both symptomatic and asymptomatic children less than three years of age at the individual and household level using a case-comparison design.^ Individual children more likely to have LT infection were those who lived in HHs that had cooked food stored for subsequent consumption at the time of the visit, where caretakers used water but not soap to clean an infant after a diarrheal stool, and that had an indoor, private water source. LT was more common in HHs where the caretaker did not clean an infant with soap after a diarrheal stool, and where a sleeping infant was not covered with a net. At both the individual and HH level, LT was significantly associated with good water supply in terms of quantity and storage.^ ST was isolated more frequently at the individual level where a sleeping infant was covered with a net, where large animals were kept in or around the house, where water was always available and was not potable, and where the water container was not covered. At the HH level, the absence of a toilet or latrine and the indiscriminate disposal of animal waste decreased risk. Using animal feces for fertilizer, the presence of large animals, and poor water quality were associated with ST at both the individual and HH level.^ These findings are mostly consistent with those of other studies, and/or are biologically plausible, with the obvious exception of those from this study where poorer water supplies are associated with less infection, at least in the case of LT. More direct observation of how animal ownership and feces disposal relates to different types of water supply and usage might clarify mechanisms through which some ETEC infection could be prevented in similar settings. ^

THE CHLOREX TREATABILITY STUDY: ENVIRONMENTAL FATE IN FACULTATIVE ANAEROBIC AND AEROBIC WASTE STABILIZATION PONDS (BIODEGRADATION, VOLATILIZATION, SORPTION, PRIORITY POLLUTANTS)

The efficacy of waste stabilization lagoons for the treatment of five priority pollutants and two widely used commercial compounds was evaluated in laboratory model ponds. Three ponds were designed to simulate a primary anaerobic lagoon, a secondary facultative lagoon, and a tertiary aerobic lagoon. Biodegradation, volatilization, and sorption losses were quantified for bis(2-chloroethyl) ether, benzene, toluene, naphthalene, phenanthrene, ethylene glycol, and ethylene glycol monoethyl ether. A statistical model using a log normal transformation indicated biodegradation of bis(2-chloroethyl) ether followed first-order kinetics. Additionally, multiple regression analysis indicated biochemical oxygen demand was the water quality variable most highly correlated with bis(2-chloroethyl) ether effluent concentration. ^

The role of environmental tobacco smoke in the development and exacerbation of asthma among children in developing countries: A systematic review

Environmental tobacco smoke (ETS) is an important indoor air pollutant associated with adverse effects on the respiratory health of the general population, especially people with asthma. ETS consists mainly of sidestream smoke from burning cigarettes and a smaller quantity of mainstream smoke which is exhaled by the smoker. At least one out of every three children is frequently exposed to ETS. ^ This paper reviewed the literature for studies on the role of ETS in the development and exacerbation of asthma among children in developing countries, specifically the low and middle income countries from the year 1980 to the present. The databases searched in this systematic review were: Ovid Medline; PubMed (National Library of Medicine); and Cumulative Index to Nursing and Allied Health (CINAHL) (EBSCOhost). Out of a total of 197 articles initially identified, only four studies (two from China, one from Macedonia and one from Brazil) were rated by two independent raters as being of high quality, and were selected for final abstraction, synthesis and evidence weighting. Results from these four studies suggests that, in developing countries, ETS exposure is associated with childhood asthma, and that asthma prevalence increases with an increase in the amount and duration of exposure to ETS. Similarly, exposure to ETS is associated with persistent cough, current night dry cough, and exacerbation of asthma symptoms. ^ Therefore, as is the case in developed nations, there is suggestive evidence in the literature that ETS exposure plays substantial role in the development and/or exacerbation of asthma among children in developing countries. To decrease the likelihood of new asthma development, enhance asthma control, and reduce the rate of medical service utilization in children exposed to ETS, smoking should be eliminated at home and in public places.^

A feasibility study for assessing building occupants' indoor air quality expectations compared to nationally recognized standards

Indoor Air Quality (IAQ) can have significant implications for health, productivity, job performance, and operating cost. Professional experience in the field of indoor air quality suggests that high expectations (better than nationally established standards) (American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE)) of workplace indoor air quality lead to increase air quality complaints. To determine whether there is a positive association between expectations and indoor air quality complaints, a one-time descriptive and analytical cross-sectional pilot study was conducted. Area Safety Liaisons (n = 330) at University of Texas Health Science Center – Houston were asked to answer a questionnaire regarding their expectations of four workplace indoor air quality indicators i.e., (temperature, relative humidity, carbon dioxide, and carbon monoxide) and if they experienced and reported indoor air quality problems. A chi-square test for independence was used to evaluate associations among the variables of interest. The response rate was 54% (n = 177). Results did not show significant associations between expectation and indoor air quality. However, a greater proportion of Area Safety Liaisons who expected indoor air quality indicators to be better than the established standard experienced greater indoor air quality problems. Similarly, a slightly higher proportion of Area Liaisons who expected indoor air quality indicators to be better than the standard reported greater indoor air quality complaints. ^ The findings indicated that a greater proportion of Area Safety Liaisons with high expectations (conditions that are beyond what is considered normal and acceptable by ASHRAE) experienced greater indoor air quality discomfort. This result suggests a positive association between high expectations and experienced and reported indoor air quality complaints. Future studies may be able to address whether the frequency of complaints and resulting investigations can be reduced through information and education about what are acceptable conditions.^

The success of worksite nutrition and physical activity interventions with environmental modifications A systematic review

Background: As obesity increases among U.S. workers, employers are implementing programs to increase physical activity and improve diets. Although programs to address individual determinants of obesity have been evaluated, less is known about the effects of workplace programs that change environmental factors, because most reviews have not isolated environmental programs; the one that did was published in 2005. ^ Objective: To update the 2005 review to determine the effectiveness of workplace environmental interventions. ^ Methods: The Medline database was searched for published English language reports (2003-2011) of randomized controlled (RCTs) or quasi-experimental trials (NRCTs) that evaluated strategies to modify physical activity opportunities or food services, targeting employees at least 18 years, not including retirees and that provided data for at least one physical activity, dietary, or health risk indicator. Three coders independently extracted study characteristics and scored the quality of study methods. Program effectiveness was determined using the 2005 review's best evidence approach. ^ Results: Seven studies represented in nine reports met eligibility criteria; three focused on diet and the remainder targeted diet and physical activity interventions. All but one study received a high quality score for internal validity. The evidence for the effectiveness of workplace environmental interventions was at best, inconclusive for diet and physical activity and limited for health risk indicators. The outcome constructs were inconsistent across the studies. ^ Conclusions: Limitations in the methods of the 2005 review made it challenging to draw conclusions about findings for this review that include: variation in outcome measures, reliance on distal measures without proximal behavior change measures, no distinction between changes at the workplace versus outside the workplace, and inappropriate analyses of cluster designs that biased findings toward statistical significance. The best evidence approach relied on vote-counting, using statistical significance alone rather than effect size and confidence intervals. Future research should address these limitations and use more rigorous methods; systematic reviews should use methods of meta-analysis to summarize study findings. These recommendations will help employers to better understand how environmental modifications in the workplace can support their efforts to combat the effects of obesity among employees.^