Grantee Research Project Results
2006 Progress Report: Dose-Response of Nitrate and Other Methemoglobin Inducers on Methemoglobin Levels of Infants
EPA Grant Number: R829781Title: Dose-Response of Nitrate and Other Methemoglobin Inducers on Methemoglobin Levels of Infants
Investigators: VanDerslice, Jim
Institution: Washington State Department of Health
EPA Project Officer: Page, Angela
Project Period: September 2, 2002 through September 1, 2005 (Extended to September 1, 2007)
Project Period Covered by this Report: September 2, 2005 through September 1, 2006
Project Amount: $594,934
RFA: Health Effects of Chemical Contaminants in Drinking Water (2001) RFA Text | Recipients Lists
Research Category: Drinking Water , Human Health , Water
Objective:
The objectives of the research project are to: (1) estimate the intake of methemoglobin inducers by infants and their effects on methemoglobin levels; (2) estimate the effect of potential endogenous production of nitrite (i.e., symptoms of infection and gastrointestinal distress) on the level of methemoglobin in infants; and (3) examine mothers’ knowledge and attitudes regarding the risks associated with the use of private well water for infants.
Progress Summary:
Data collection was completed in October 2005. Overall, 736 interviews were completed—59 percent of the 1,258 mothers who were contacted and eligible to be in the study (Table 1). Most of those who were ineligible had moved out of the study area or lived in an area served by a public water supply.
Table 1. Status of Recruiting
| Status | Number | % of Group Noted | |||||||||||
| Infants selected | 1,940 | ||||||||||||
| No Contact | 392 | (20.2% of those selected) | |||||||||||
| Contacted | 1,548 | (79.8% of those selected) | |||||||||||
| Deceased | 1 | ||||||||||||
| Not eligible | 197 | (12.7% of those contacted) | |||||||||||
| Refused | 522 | (33.7% of those contacted) | |||||||||||
| Recruited | 828 | (53.5% of those contacted) | |||||||||||
| Refused at interview | 92 | (11.1% of those recruited) | |||||||||||
| Completed interview | 736 | (88.9% of those recruited) |
Data from the interviews, the blood sampling for methemoglobin levels and the water quality analyses were reviewed and subsequently entered into a relational database (Microsoft Access®) with custom data entry screens and built-in range checks and consistency checks. The data were converted to SAS format and analyzed using SAS® version 9 (Cary, NC).
Univariate and bivariate analyses were carried out. The preliminary results were presented to personnel from Washington State Department of Health and from local health jurisdictions responsible for providing oversight and assistance to small unregulated water systems and individuals with private wells. Some of the preliminary results are presented below.
Just more than one-half of the respondents (54%) had their own well; 45 percent were served by small, unregulated water systems. About 30 percent of household kitchen tap samples were positive for total coliforms, and 1.5 percent were positive for Escherichia coli. However, after the tap had been disinfected and the aerator screen removed, the proportion of positive samples dropped to 9.2 percent and 0.4 percent, respectively.
About three-quarters of the households had nitrate levels (NO3-N) of less than 5 mg/L, whereas another 15 percent were between 5 and 10 mg/L. Just under 10 percent of the households had tap water exceeding the maximum contaminant level of 10 mg/L.
Methemoglobin levels were obtained from 585 of the enrolled infants. A normal range of methemoglobin for infants has not been established. However, 2 percent had levels above the 3 percent methemoglobin that is considered elevated among adults. Almost 10 percent (9.2%) of sampled infants had levels between 2 and 3 percent methemoglobin.
Data analyses are continuing. Estimates of total nitrate exposure are being prepared combining water quality, water consumption, medication usage, and consumption of foods containing nitrate. Multivariate analyses will be conducted. A second analysis will be carried out using data from this study and a similar study conducted in the same region in 2000-2001.
Future Activities:
Further analyses will be conducted in the next year. We will combine our data with similar data from the Columbia Basin Infant Health Study and re-run the analyses. We will present findings at national and international meetings, such as the Conference of the International Society for Environment Epidemiology and the Conference of the International Society for Exposure Analysis. We also will prepare and publish papers in peer-reviewed journals.
Journal Articles:
No journal articles submitted with this report: View all 6 publications for this projectSupplemental Keywords:
drinking water, nitrate, infants, methemoglobinemia, “blue-baby” syndrome,, RFA, Health, Scientific Discipline, Water, Health Risk Assessment, Risk Assessments, Environmental Chemistry, Analytical Chemistry, Children's Health, Biochemistry, Drinking Water, health effects, human health, dietary exposure, other - exposure, methemoglobin formation, nitrate contamination, water quality, human exposure, chemical contaminants, dietary ingestion exposures, chemical exposure, children, drinking water contaminants, exposure, groundwater, methemoglobin, children's vulnerablity, human health effects, human health risk, assessment of exposure, exposure and effects, exposure assessmentProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.