The microbiome: a contributor to health and disease.

As the 21st century unfolds there is substantial evidence that biological research is experiencing extraordinary scientific and technological advances. Prominent among these advances are the completion of the Human Genome Project, which laid the foundation for the second advance, the Human Microbiome Project. Emerging from these advances are two overarching conclusions: a) genomics is no longer the sole domain of the geneticist, and b) we each are hosts to trillions of microorganisms. Genomics and other technologies have enhanced efforts to characterize the structure, composition, and functions of the microbiome. This characterization has fueled progress in understanding the role of the microbiome in health and disease. In this review, we highlight developments that have helped illuminate the microbiome-health connection. This information can improve an understanding of connections and relationships among multiple factors (or determinants) of health.

Medicaid patient asthma-related acute care visits and their associations with ozone and particulates in Washington, DC, from 1994-2005.

The primary objective of this ecologic and contextual study is to determine statistically significant short-term associations between air quality (daily ozone and particulate concentrations) and Medicaid patient general acute care daily visits for asthma exacerbations over 11 years for Washington, DC residents, and to identify regions and populations that may experience increased asthma exacerbations related to air quality. After removing long-term trends and day-of-week effects in the Medicaid data, Poisson regression was applied to daily time series data. Significant associations were found between asthma-related general acute care visits and ozone concentrations. Significant associations with both ozone and PM2.5 concentrations were observed for 5- to 12-year-olds. While poor air quality was closely associated with asthma exacerbations observed in acute care visits in areas where Medicaid enrollment was high, the strongest associations between asthma-related visits and air quality were not always for the areas with the highest Medicaid enrollment.

Elevated lead in drinking water in Washington, DC, 2003-2004: the public health response.

BACKGROUND: In 2003, residents of the District of Columbia (DC) experienced an abrupt rise in lead levels in drinking water, which followed a change in water-disinfection treatment in 2001 and which was attributed to consequent changes in water chemistry and corrosivity. OBJECTIVES: To evaluate the public health implications of the exceedance, the DC Department of Health expanded the scope of its monitoring programs for blood lead levels in children. METHODS: From 3 February 2004 to 31 July 2004, 6,834 DC residents were screened to determine their blood lead levels. RESULTS: Children from 6 months to 6 years of age constituted 2,342 of those tested; 65 had blood lead levels > 10 microg/dL (the "level of concern" defined by the Centers for Disease Control and Prevention), the highest with a level of 68 microg/dL. Investigation of their homes identified environmental sources of lead exposure other than tap water as the source, when the source was identified. Most of the children with elevated blood lead levels (n = 46; 70.8%) lived in homes without lead drinking-water service lines, which is the principal source of lead in drinking water in older cities. Although residents of houses with lead service lines had higher blood lead levels on average than those in houses that did not, this relationship is confounded. Older houses that retain lead service lines usually have not been rehabilitated and are more likely to be associated with other sources of exposure, particularly lead paint. None of 96 pregnant women tested showed blood lead levels > 10 microg/dL, but two nursing mothers had blood lead levels > 10 microg/dL. Among two data sets of 107 and 71 children for whom paired blood and water lead levels could be obtained, there was no correlation (r(2) = -0.03142 for the 107). CONCLUSIONS: The expanded screening program developed in response to increased lead levels in water uncovered the true dimensions of a continuing problem with sources of lead in homes, specifically lead paint. This study cannot be used to correlate lead in drinking water with blood lead levels directly because it is based on an ecologic rather than individualized exposure assessment; the protocol for measuring lead was based on regulatory requirements rather than estimating individual intake; numerous interventions were introduced to mitigate the effect; exposure from drinking water is confounded with other sources of lead in older houses; and the period of potential exposure was limited and variable.

Pediatric patient asthma-related emergency department visits and admissions in Washington, DC, from 2001-2004, and associations with air quality, socio-economic status and age group.

BACKGROUND: The District of Columbia (DC) Department of Health, under a grant from the US Centers for Disease Control and Prevention, established an Environmental Public Health Tracking Program. As part of this program, the goals of this contextual pilot study are to quantify short-term associations between daily pediatric emergency department (ED) visits and admissions for asthma exacerbations with ozone and particulate concentrations, and broader associations with socio-economic status and age group. METHODS: Data included daily counts of de-identified asthma-related pediatric ED visits for DC residents and daily ozone and particulate concentrations during 2001-2004. Daily temperature, mold, and pollen measurements were also obtained. After a cubic spline was applied to control for long-term seasonal trends in the ED data, a Poisson regression analysis was applied to the time series of daily counts for selected age groups. RESULTS: Associations between pediatric asthma ED visits and outdoor ozone concentrations were significant and strongest for the 5-12 year-old age group, for which a 0.01-ppm increase in ozone concentration indicated a mean 3.2% increase in daily ED visits and a mean 8.3% increase in daily ED admissions. However, the 1-4 yr old age group had the highest rate of asthma-related ED visits. For 1-17 yr olds, the rates of both asthma-related ED visits and admissions increased logarithmically with the percentage of children living below the poverty threshold, slowing when this percentage exceeded 30%. CONCLUSION: Significant associations were found between ozone concentrations and asthma-related ED visits, especially for 5-12 year olds. The result that the most significant ozone associations were not seen in the age group (1-4 yrs) with the highest rate of asthma-related ED visits may be related to the clinical difficulty in accurately diagnosing asthma among this age group. We observed real increases in relative risk of asthma ED visits for children living in higher poverty zip codes versus other zip codes, as well as similar logarithmic relationships for visits and admissions, which implies ED over-utilization may not be a factor. These results could suggest designs for future epidemiological studies that include more information on individual exposures and other risk factors.

Environmental factors associated with asthma.

Asthma, a disease of attacks and remission, continues to account for substantial morbidity and direct economic costs. Numerous studies--epidemiologic, toxicologic and clinical--present evidence for a broad spectrum of environmental risk factors associated with asthma. This review summarizes current thinking on a subset of these factors. Knowledge of potential environmental determinants of asthma is important to both the patient and healthcare professional in the application of multiple modalities of medical and environmental intervention for management of the development, and exacerbation of this chronic inflammatory disorder of the airways.

Association between bone lead concentration and blood pressure among young adults.

BACKGROUND: Occupational and environmental exposure to lead has been examined for its effect on blood pressure (BP) in adults with varying results. The present analyses assessed the association between bone lead concentration and BP in early adult life in persons exposed during childhood. METHODS: Study participants included young adult members of two cohorts with different past histories of lead exposure. Lead exposure was assessed using noninvasive K-X-ray fluorescence spectroscopy to quantify bone lead concentration, an index of long-term lead exposure superior to current blood lead concentration. Systolic and diastolic BP measurements were obtained using conventional clinical methods. Multiple linear regression models were constructed to allow for control of covariates of BP identified a priori. RESULTS: Analyses were performed on 508 participants. While controlling for potential confounders, systolic BP was 4.3 mm Hg greater among members of the highest of four bone lead concentration groups (> 10 microg Pb/g bone) when compared with the lowest bone lead concentration group (< 1 microg Pb/g bone; P = 0.004), and diastolic BP was 2.8 mm Hg greater among members of the highest bone lead concentration group when compared with the lowest bone lead concentration group (P = 0.03). CONCLUSIONS: These results suggest that substantial lead exposure during childhood can increase BP during young adulthood.