Communicating results to community residents: lessons from recent ATSDR health investigations.

As a public health agency within the US Department of Health and Human Services, the Agency for Toxic Substances and Disease Registry (ATSDR) is responsible for implementing the health-related provisions of the Superfund Act. Much of its work is carried out to address health concerns in communities near sources of environmental contamination, usually in consultation with other local, state, and federal agencies. Over the last decade, ATSDR has considered, supported or conducted health investigations in a variety of different communities across the country. Communication with community residents has been an integral part of the process in all of these activities. The approach to communicating results needs to begin early by developing relationships and clarifying expectations, and it needs to remain flexible. Through examples taken from specific situations, we illustrate many of the lessons we have gained from trying to apply the principles of good community involvement to the design and conduct of health investigations and to the communication of study results.

Ambient hydrogen sulfide, total reduced sulfur, and hospital visits for respiratory diseases in northeast Nebraska, 1998-2000.

This analysis examined associations between total reduced sulfur (TRS) and hydrogen sulfide (H(2)S) levels, and hospital visits for respiratory disease among residents of Dakota City and South Sioux City, Nebraska, from January 1998 to May 2000. For reference, the association between TRS, H(2)S, and digestive diseases was also examined. Time-series analyses of daily hospital visits in the selected outcome categories and measures of TRS and H(2)S were performed using generalized additive models with a Poisson link. TRS and H(2)S levels were categorized as high if at least one of the daily 30-min rolling averages was > or =30 ppb and as low if every rolling average was <30 ppb. Loess smoothers allowed for flexible modeling of the time effect and the effect of temperature and relative humidity. The measure of association used was the mean percent change in the average number of hospital visits recorded following a day with a high exposure versus a day with a low exposure. For children less than 18 years of age, a positive association was found between asthma hospital visits and 1-day lagged TRS levels. For adults, a positive association was found between asthma hospital visits and H(2)S levels on the previous day. A positive association also was found between hospital visits for all respiratory diseases, and H(2)S and TRS levels on the previous day for children but not for adults. No association was found between contaminant levels and hospital visits for all digestive diseases. These findings suggest that TRS or H(2)S levels may be associated with exacerbations of asthma or other respiratory diseases among the residents of Dakota City and South Sioux City.

Confirming the utility of four kidney biomarker tests in a longitudinal follow-up study.

In this follow-up study, 526 persons were followed for almost 5 years to assess the reversibility and predictive value of four kidney biomarkers in a field epidemiology setting. This study examined (a) whether elevations in urinary albumin, N-acetyl-beta-D-glucosaminidase, retinol-binding protein, and alanine aminopeptidase remained elevated at follow-up and (b) whether these initial elevations were predictive of kidney disease (as measured by markers of kidney dysfunction: serum creatinine, serum cystatin C, creatinine clearance, and urine osmolality) at follow-up. Study participants were 8-76 years of age at baseline and were followed for an average of 4.5 years. Approximately 50% of adults who had an elevated biomarker did not have an elevation at followup. Youths with elevated biomarkers at baseline, but who completed adolescence by the time of the follow-up, no longer had any elevations in biomarkers at follow-up. Adult participants who had elevated biomarkers and selected health conditions at baseline (diabetes and, to a lesser extent, heart disease, hypertension, gout, and urinary tract disease) were more likely to show early indicators of kidney impairment at follow-up. Participants with these health conditions and normal kidney biomarker values at baseline had kidney test results at follow-up that were similar to results of study participants who did not have these health conditions at baseline. The presence or absence of elevated biomarkers at baseline among generally healthy participants was not associated with the development of early indicators of kidney impairment at follow-up. This longitudinal study confirmed the utility of these four kidney biomarker tests as markers of preclinical organ dysfunction among adults with certain preexisting medical conditions.

Could monoamine plasma levels and erythrocyte membrane ATPase activities at birth be predictive for future hand performance?

The monoamine and intracellular calcium systems are two major elements of nervous system functions. However, their role in human brain development is unclear. We studied the association between activity of monoamine and intracellular calcium systems during prenatal life and subsequent psychomotor performances in healthy children. We used prospective data from 247 children followed from birth through 6 y of age. Among those, 195 were examined at 9 mo using the Brunet-Lézine Scales, whereas 126 were examined at 3 y and 100 at 6 y using the McCarthy Scales of Children's Ability. A blood sample was collected from the umbilical cord to measure levels of dopamine and serotonin metabolites (homovanillic acid and 5-hydroxyindoleacetic acid, respectively) and ATPase activities (Na+K+-ATPase and Ca2+Mg2+-ATPase). The hand skill score at 6 y of age was significantly and negatively correlated with ATPase activities and with monoamine metabolite concentrations. No other cognitive score was related to biochemical measures at birth. Results were adjusted for child's sex, mother's educational level, duration of labor, and tea consumption. Composite scores of ATPase activities and monoamine metabolite concentrations measured at birth explained 29% of hand skill score variance at 6 y. Our results demonstrate the importance of prenatal factors on monoaminergic and ATPase activities in early human psychomotor development. This study also suggests that specific psychometric measures such as fine motor tests may be a better developmental measurement to correlate with biochemical factors than general cognitive scales.

Community-based exposure estimate for hydrogen sulfide.

Indoor and outdoor air pollution monitoring may indicate potential human exposure to air contaminants. Individual and population exposures to air contaminants depend upon many factors including time spent outdoors and indoors, permeability of housing structures, and mobility within a community. In this report, we illustrate an approach for using long-term air monitoring to establish patterns or changes of environmental exposures, improve validity and representativeness of data, and prevent exposure misclassification. Long-term air monitoring for hydrogen sulfide (H2S) at 14 Dakota City, Nebraska, residences identified differences in area-wide concentration levels, geographic locations, and seasonal exposures. Air data for 1999 indicated that Dakota City residents were repeatedly exposed, both indoors and outdoors, to moderate levels (>or=90 parts per billion [ppb]) of H2S. Using GIS modeling and kriging, we produced a geographic gradient of exposure estimate or map for ambient H2S. These findings formed the basis for designing two health investigations for this community.

Effects of exposure to low levels of environmental cadmium on renal biomarkers.

We conducted a study among residents of a small community contaminated with heavy metals from a defunct zinc smelter and residents from a comparison community to determine whether biologic measures of cadmium exposure were associated with biomarkers of early kidney damage. Creatinine-adjusted urinary cadmium levels did not differ between the smelter and comparison communities; thus we combined individuals from both communities (n = 361) for further analyses. The overall mean urinary cadmium level was low, 0.26 microg/g creatinine, similar to reference values observed in the U.S. general population. For children ages 6-17 years, urinary concentration of N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), and albumin were positively associated with urinary cadmium, but these associations did not remain statistically significant after adjusting for urinary creatinine and other potential confounders. For adults ages 18 or older, urinary concentration of NAG, AAP, and albumin were positively associated with urinary cadmium. The associations with NAG and AAP but not with albumin remained statistically significant after adjusting for creatinine and other potential confounders. We found a positive dose-effect relationship between levels of creatinine-adjusted urinary cadmium and NAG and AAP activity, and statistically significant differences in mean activity for these two enzymes between the highest (> or =1.0 microg cadmium/g creatinine) and the lowest (< or =0.25 microg cadmium/g creatinine) exposure groups. The findings of this study indicate that biologic measures of cadmium exposure at levels below 2.0 microg/g creatinine may produce measurable changes in kidney biomarkers.