Ambient air pollution and cardiovascular emergency department visits

BACKGROUND

Despite evidence supporting an association between ambient air pollutants and cardiovascular disease (CVD), the roles of the physicochemical components of particulate matter (PM) and copollutants are not fully understood. This time-series study examined the relation between ambient air pollution and cardiovascular conditions using ambient air quality data and emergency department visit data in Atlanta, Georgia, from January 1, 1993, to August 31, 2000.

METHODS

Outcome data on 4,407,535 emergency department visits were compiled from 31 hospitals in Atlanta. The air quality data included measurements of criteria pollutants for the entire study period, as well as detailed measurements of mass concentrations for the fine and coarse fractions of PM and several physical and chemical characteristics of PM for the final 25 months of the study. Emergency department visits for CVD and for cardiovascular subgroups were assessed in relation to daily measures of air pollutants using Poisson generalized linear models controlling for long-term temporal trends and meteorologic conditions with cubic splines.

RESULTS

Using an a priori 3-day moving average in single-pollutant models, CVD visits were associated with NO2, CO, PM2.5, organic carbon, elemental carbon, and oxygenated hydrocarbons. Secondary analyses suggested that these associations tended to be strongest with same-day pollution levels.

CONCLUSIONS

These findings provide evidence for an association between CVD visits and several correlated pollutants, including gases, PM2.5, and PM2.5 components.

Physician training in agricultural safety and health: the Emory Agromedicine Training Project

This paper describes the Emory Agromedicine Training Project, a component of Occupational Medicine residency training at Emory University since 1991. The Project places occupational medicine residents in rural settings, where they perform a range of activities: working on farms, service visits to farms, grand rounds presentations to rural hospitals, public presentations in farm communities, and clinical service in the migrant health program. In addition they complete a directed reading syllabus and a research project. The rotation has been successful in building the residents' knowledge of agricultural safety and health, instilling positive attitudes toward the field, and achieving desired behaviors and skills. In addition, strong statewide networking was accomplished through this initiative. Areas of limited success include the small number of residents trained, some resident dissatisfaction with intense travel requirements and security concerns, and inability to secure long-term funding. We conclude that agricultural safety and health is highly suitable for inclusion in occupational medicine training, and this model should be extended to primary care specialties such as family practice.

The impact of community design and land-use choices on public health: a scientific research agenda

The design of a community's built environment influences the physical and mental health of its residents. Because few studies have investigated this relationship, the Centers for Disease Control and Prevention hosted a workshop in May 2002 to help develop a scientific research agenda on these issues. Workshop participants' areas of expertise included physical activity, injury prevention, air pollution, water quality, urban planning, transportation, architecture, epidemiology, land use, mental health, social capital, housing, and social marketing. This report describes the 37 questions in the resulting research agenda. The next steps are to define priorities and obtain resources. The proposed research will help identify the best practices for designing new communities and revitalizing old ones in ways that promote physical and mental health.

Healthy places: exploring the evidence

"Sense of place" is a widely discussed concept in fields as diverse as geography, environmental psychology, and art, but it has little traction in the field of public health. The health impact of place includes physical, psychological, social, spiritual, and aesthetic outcomes. In this article, the author introduces sense of place as a public health construct. While many recommendations for "good places" are available, few are based on empirical evidence, and thus they are incompatible with current public health practice. Evidence-based recommendations for healthy place making could have important public health implications. Four aspects of the built environment, at different spatial scales-nature contact, buildings, public spaces, and urban form-are identified as offering promising opportunities for public health research, and potential research agendas for each are discussed.

Prevalence of hepatitis A virus infection among sewage workers in Georgia

BACKGROUND

Wastewater (WW) workers could have opportunity for direct contact with raw sewage, which might contain hepatitis A virus (HAV).

METHODS

A serologic survey of WW workers and a comparison population of roads and drainage workers (RD). Factors potentially associated with anti-HAV positivity were evaluated in univariate and multivariate analyses.

RESULTS

Among the 365 WW workers, overall anti-HAV prevalence was 38%, similar to that (35%) of the 166 RD workers (P = 0.5). Prevalence varied by wastewater job type from 45% among the 164 field crew workers to 32% among the 201 treatment plant workers. In multivariate modeling, factors associated with anti-HAV positivity included age > or = 40 years (odds ratio [OR] = 2.4; 95% CI = 1.6-3.7), black compared to other races (OR = 2.4; 95% CI = 1.5-3.8), birth outside the United States (OR = 7.5; 95% CI = 3.0-18.6), a high school education or less (OR 2.1; 95% CI = 1.4-3.2) and work on the field crew compared to RD work (OR 1.6; 95% CI = 1.1-2.4).

CONCLUSIONS

These results are consistent with no or a small increased risk of hepatitis A among WW workers, and do not provide a clear mandate for hepatitis A vaccination of these workers. Am. J. Ind. Med. 43: 172-178, 2003.

Organochlorines and breast cancer risk

Organochlorines are a diverse group of synthetic chemicals that include polychlorinated biphenyls (PCBs), dioxins, and organochlorine pesticides such as dichlorodiphenyl-trichloroethane (DDT), lindane, and hexachlorobenzene. Although use of DDT and PCBs has been banned in the United States since the 1970s, some organochlorine compounds have accumulated and persisted within the environment. As a result, measurable amounts can still be found in human tissue. Because some organochlorine compounds act as estrogen agonists or antagonists within in vitro and experimental animal systems, a possible association of breast cancer risk with organochlorine exposure has been hypothesized and investigated. Although a few studies support this hypothesis, the vast majority of epidemiological studies do not. While some of these compounds may have other adverse environmental or health effects, organochlorine exposure is not believed to be causally related to breast cancer. Women concerned about possible organochlorine exposure can be reassured that available evidence does not suggest an association between these chemicals and breast cancer.

The environmental history in pediatric practice: a study of pediatricians' attitudes, beliefs, and practices

We conducted a mail survey of practicing pediatricians in Georgia to assess their knowledge, attitudes, and behaviors regarding recording patients' environmental histories. Of 477 eligible pediatricians, 266 (55.8%) responded. Fewer than one in five reported having received training in environmental history-taking. Pediatricians reported that they strongly believe in the importance of environmental exposures in children's health, and 53.5% of respondents reported experience with a patient who was seriously affected by an environmental exposure. Pediatricians agreed moderately strongly that environmental history-taking is useful in identifying potentially hazardous exposures and in helping prevent these exposures. Respondents reported low self-efficacy regarding environmental history-taking, discussing environmental exposures with parents, and finding diagnosis and treatment resources related to environmental exposures. The probability of self-reported history-taking varied with the specific exposure, with environmental tobacco smoke and pets most frequently queried and asbestos, mercury, formaldehyde, and radon rarely queried. The pediatricians' preferred information resources include the American Academy of Pediatrics, newsletters, and patient education materials. Pediatricians are highly interested in pediatric environmental health but report low self-efficacy in taking and following up on environmental histories. There is considerable opportunity for training in environmental history-taking and for increasing the frequency with which such histories are taken.

Radon

Residential and occupational exposure to radon is the second leading cause of lung cancer after cigarette smoking. As many as eight million homes in the US have elevated radon levels according to Environmental Protection Agency estimates. High exposure levels in homes are largely a result of radon-contaminated gas rising from the soil. This makes it an unusual indoor air pollutant in that it has a natural source. This study examines the synergism between smoking and radon, what levels are considered safe, and what to do to safeguard against overexposure to radon.

Blood lead in children and its determinants in Nagpur, India

In a community-based cross-sectional study of 297 children aged 6 months to 6 years in an Indian city, the authors assessed the prevalence of elevated (> or = 10 microg/dL) blood lead (PbB) levels, their risk factors, and the lead contents in potential environmental sources. Mean PbB was 18.4 microg/dL +/- 16.5. The prevalence of elevated PbB was 67%. Anticipated risk factors for elevated PbB were living in houses painted with lead-based paint, odds ratio (OR) 6.42 (1.75, 23.6; p = 0.005), recent exposures to lead-based paint, OR 2.61 (1.07, 6.66; p = 0.03), and the use of the eye cosmetic ma," OR 2.63 (1.24, 5.56; p = 0.01). Unanticipated results were effect of upper caste as a risk factor, OR (adjusted) 1.85 (95% CI = 0.96, 3.57; p = 0.06), and the lack of effect of traffic, parental occupational exposure, or nutritional status. Analysis of various environmental sources such as paint, pencils, crayons, and clay revealed high lead levels. These results demonstrate the existence of a major environmental health problem in Indian children, with risk factors that differ from those in other countries.

Arsenic

The toxicity and carcinogenicity of arsenic are well known, but vexing questions remain. The current controversy over the appropriate Federal limit for arsenic in drinking water highlights some of the difficult scientific, ethical, economic, and political issues that complicate standard-setting in occupational and environmental health. These include limitations in the scientific evidence concerning the risk at low doses, uncertainty about the appropriate mathematical models for estimating the risk at low-level exposures based on data from higher-level exposures, and controversies concerning the appropriate safety margin, level of evidence required for standard-setting, and costs of remediation.

Beyond toxicity: human health and the natural environment

Research and teaching in environmental health have centered on the hazardous effects of various environmental exposures, such as toxic chemicals, radiation, and biological and physical agents. However, some kinds of environmental exposures may have positive health effects. According to E.O. Wilson's "biophilia" hypothesis, humans are innately attracted to other living organisms. Later authors have expanded this concept to suggest that humans have an innate bond with nature more generally. This implies that certain kinds of contact with the natural world may benefit health. Evidence supporting this hypothesis is presented from four aspects of the natural world: animals, plants, landscapes, and wilderness. Finally, the implications of this hypothesis for a broader agenda for environmental health, encompassing not only toxic outcomes but also salutary ones, are discussed. This agenda implies research on a range of potentially healthful environmental exposures, collaboration among professionals in a range of disciplines from public health to landscape architecture to city planning, and interventions based on research outcomes.

Cellular phones and risk of brain tumors

As cellular telephones are a relatively new technology, we do not yet have long-term follow-up on their possible biological effects. However, the lack of ionizing radiation and the low energy level emitted from cell phones and absorbed by human tissues make it unlikely that these devices cause cancer. Moreover, several well-designed epidemiologic studies find no consistent association between cell phone use and brain cancer. It is impossible to prove that any product or exposure is absolutely safe, especially in the absence of very long-term follow-up. Accordingly, the following summary from the Food and Drug Administration Center for Devices and Radiological Health offers advice to people concerned about their risk: If there is a risk from these products--and at this point we do not know that there is--it is probably very small. But if people are concerned about avoiding even potential risks, there are simple steps they can take to do so. People who must conduct extended conversations in their cars every day could switch to a type of mobile phone that places more distance between their bodies and the source of the RF, since the exposure level drops off dramatically with distance. For example, they could switch to: a mobile phone in which the antenna is located outside the vehicle, a hand-held phone with a built-in antenna connected to a different antenna mounted on the outside of the car or built into a separate package, or a headset with a remote antenna to a mobile phone carried at the waist. Again the scientific data do not demonstrate that mobile phones are harmful. But if people are concerned about the radiofrequency energy from these products, taking the simple precautions outlined above can reduce any possible risk. In addition, people who are concerned might choose digital rather than analog telephones, since the former use lower RF levels.

Diagnostic chelation challenge with DMSA: a biomarker of long-term mercury exposure?

Chelation challenge testing has been used to assess the body burden of various metals. The best-known example is EDTA challenge in lead-exposed individuals. This study assessed diagnostic chelation challenge with dimercaptosuccinic acid (DMSA) as a measure of mercury body burden among mercury-exposed workers. Former employees at a chloralkali plant, for whom detailed exposure histories were available (n = 119), and unexposed controls (n = 101) completed 24-hr urine collections before and after the administration of two doses of DMSA, 10 mg/kg. The urinary response to DMSA was measured as both the absolute change and the relative change in mercury excretion. The average 24-hr mercury excretion was 4.3 microg/24 hr before chelation, and 7.8 microg/24 hr after chelation. There was no association between past occupational mercury exposure and the urinary excretion of mercury either before or after DMSA administration. There was also no association between urinary mercury excretion and the number of dental amalgam surfaces, in contrast to recent published results. We believe the most likely reason that DMSA chelation challenge failed to reflect past mercury exposure was the elapsed time (several years) since the exposure had ended. These results provide normative values for urinary mercury excretion both before and after DMSA challenge, and suggest that DMSA chelation challenge is not useful as a biomarker of past mercury exposure.

Reconstruction of occupational mercury exposures at a chloralkali plant

OBJECTIVE

To reconstruct historical workplace exposure to mercury (Hg) from 1956 to 1994 at a large chloralkali factory for use in a current epidemiology study of the factory.

METHODS

All job activities of the employees were classified into one of 16 exposure categories, and the dates of changes in the processes were identified. Exposures to Hg for each job category, at each period of the plant's operation, were then reconstructed from several data sources. A job-time period-exposure matrix was created, and the individual exposures of former workers were calculated. Data on exposure to Hg in air were compared with modelled concentrations of Hg in air and data on urinary Hg of the employees.

RESULTS

Within an exposure category, concentrations of Hg in air were fairly constant for the first 20 years of the factory's operation, but began to increase in the late 1970s. Employees working in the cell room had the greatest exposures to Hg. The exposure estimates had significant correlations (p<0.001) with the urinary data and were well within the modelled range of concentrations of Hg in air.

CONCLUSIONS

The highest exposures occurred from 1987 until the plant closed in early 1994 with some exposure categories having time weighted average exposures to Hg greater than 140 microg/m(3).

Health effects of long-term mercury exposure among chloralkali plant workers

BACKGROUND

Inorganic mercury is toxic to the nervous system, kidneys, and reproductive system. We studied the health effects of mercury exposure among former employees of a chloralkali plant that operated from 1955 to 1994 in Georgia.

METHODS

Former plant workers and unexposed workers from nearby employers were studied. Exposure was assessed with a job-exposure matrix based on historical measurements and personnel records. Health outcomes were assessed with interviews, physical examinations, neurological and neurobehavioral testing, renal function testing, and urinary porphyrin measurements. Exposure-disease associations were assessed with multivariate modeling.

RESULTS

Exposed workers reported more symptoms, and tended toward more physical examination abnormalities, than unexposed workers. Exposed workers performed worse than unexposed subjects on some quantitative tests of vibration sense, motor speed and coordination, and tremor, and on one test of cognitive function. Few findings remained significant when exposure was modeled as a continuous variable. Neither renal function nor porphyrin excretion was associated with mercury exposure.

CONCLUSIONS

Mercury-exposed chloralkali plant workers reported more symptoms than unexposed controls, but no strong associations were demonstrated with neurological or renal function or with porphyrin excretion.

Occupational and environmental medicine and primary care

This article introduces occupational and environmental medicine (OEM) to physicians in other specialties, and especially to primary care physicians, by highlighting the common foundations of OEM practice and primary care practice. These common foundations include careful diagnosis and treatment, appropriate use of consultants, collaboration with non-medical professionals, attention to psychosocial issues, care of the entire family, respect for confidentiality, patient education, preventing disability and maximizing function, diligent patient follow-up, epidemiological thinking, and continuing medical education.

The international trade in toxic waste: the case of Sihanoukville, Cambodia

In December 1998, 2,700 metric tons of industrial waste containing high levels of mercury and other metals and possibly other toxic compounds were shipped illegally from Taiwan to Sihanoukville, Cambodia. There the waste was unloaded and transferred to a nearby inland dumpsite. An estimated 2,000 Sihanoukville residents were exposed to the waste occupationally or environmentally, and at least six deaths and hundreds of injuries have been associated with the incident. The authors describe the human exposures and associated morbidity and mortality, recount the medical and public health response, and consider the issues complicating epidemiologic analysis of the incident. They also consider the major issues highlighted by the incident, including the trade in toxic waste between developed and less developed countries, the factors that shape emergency public health responses in resource-poor environments, and the importance of prevention and preparedness in containing emergencies in developing countries.

Interim results of the study of particulates and health in Atlanta (SOPHIA)

Substantial evidence supports an association of particulate matter (PM) with cardiorespiratory illnesses, but little is known regarding characteristics of PM that might contribute to this association and the mechanisms of action. The Atlanta superstation sponsored by the Electric Power Research Institute as part of the Aerosol Research and Inhalation Epidemiology Study (ARIES) study is monitoring chemical composition of ambient particles by size fraction, as well as a comprehensive suite of other pollutants, at a site in downtown Atlanta during the 25-month period, August 1, 1998-August 31, 2000. Our investigative team is making use of this unique resource in several morbidity studies, called the "Study of Particulates and Health in Atlanta (SOPHIA)". The study includes the following components: (1) a time series investigation of emergency department (ED) visits for the period during which the superstation is operating; (2) a time series investigation of ED visits during the 5 years prior to implementation of the superstation; and (3) a study of arrhythmic events in patients equipped with automatic implantable cardioverter defibrillators (AICDs) for the period January 1, 1993-August 31, 2000. Thirty-three of 39 Atlanta area EDs are participating in the ED studies, comprising over a million annual ED visits. In this paper, we present initial analyses of data from 18 of the 33 participating EDs. The preliminary data set includes 1,662,713 ED visits during the pre-superstation time period and 559,480 visits during the superstation time period. Visits for four case groupings--asthma, chronic obstructive pulmonary disease (COPD), dysrhythmia, and all cardiovascular diseases (CVDs) combined--have been assessed relative to daily air quality indices, controlling for long-term temporal trends and meteorologic variables, using general linear models, generalized estimating equations and generalized additive models. Single-pollutant models predicting case visitation rates using moving averages of 0-, 1-, and 2-day lagged air quality variables were run. For the pre-superstation period, PM10 (24-h), ozone (8-h), SO2 (1-h), NO2 (1-h) and CO (1-h) were studied. For the first 12 months of superstation operation, the following air quality variables of a priori interest were available: ozone (8-h), NO2 (1-h), SO2 (1-h), CO (1-h), and 24-h measurements of PM10, coarse PM (PM 2.5-10 microm), PM2.5, polar VOCs, 10-100 nm particulate count and surface area, and in the PM2.5 fraction: sulfates, acidity, water-soluble metals, organic matter (OM), and elemental carbon (EC). During the pre-superstation time period, statistically significant, positive associations were observed for adult asthma with ozone, and for COPD with ozone, NO2 and PM10. During the superstation time period, the following statistically significant, positive associations were observed: dysrhythmia with CO, coarse PM, and PM2.5 EC; and all CVDs with CO, PM2.5 EC and PM2.5 OM. While covariation of many of the air quality indices limits the informativeness of this analysis, the study provides one of the first assessments of PM components in relation to ED visits.

Use of a job-exposure matrix to assess occupational exposures in relation to birth defects

Accurate exposure assessment remains a challenge in occupational epidemiology. We evaluated one approach, use of a job-exposure matrix (JEM), by applying the National Institute for Occupational Safety and Health (NIOSH) JEM to a large case-control birth defects study that included parental occupation information. We investigated the JEM exposure predictions in several ways and found that for a substantial proportion of the parents in the birth defects study, the JEM yielded either no exposure data or nonsense predictions. Among exposure predictions that were plausible, most were of low probability. The high probability exposure predictions were statistically unstable, and neither low nor high probability exposure predictions were reliable. There was considerable discrepancy between the JEM predictions and expert assessments for five exposures of interest. Application of the NIOSH JEM to the birth defects study database (and probably other databases as well) does not provide a useful means of assessing occupational exposures.