National Health and Nutrition Examination Survey

Lead is a known environmental toxin that has been shown to deleteriously affect the nervous, hematopoietic, endocrine, renal, and reproductive systems. In young children, lead exposure is a particular hazard because children more readily absorb lead than do adults, and children's developing nervous systems also make them more susceptible to the effects of lead. Since first measuring blood lead during the 1976–1980 survey, NHANES has been the cornerstone for lead exposure surveillance in the U.S.

In 1999, NHANES began to collect dust samples from the homes of children 1–5 years of age to be tested for the presence of lead. Lead in dust is most often the result of old, peeling, or chipping lead-based paint. As part of the household visit, NHANES interviewers collected separate dust-wipe samples from the floor and window sill of one room in the home. Signing of a special informed consent was required prior to the collection.

Eligible survey participants were households with children 1–5 years of age.

The preparation procedure for dust-wipe sample digestion involves the quantitative transfer of the sample from the container into a beaker, and then the subsequent addition of nitric and hydrochloric acids and hot-plate heating. The procedure is described in the Appendix of the Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing (1). The technique does not involve complete digestion of the sample, but does entail leaching of the lead (Pb) from the collected dust. Recovery of the method is based and evaluated on the results of matrix (wipe) spiked National Institute of Standards and Technology (NIST) quality control samples. The lead content of the digestate is determined by using a PerkinElmer Flame Atomic Absorption Spectrometer (FAAS) Model 5000 or 5100 for all window dust-wipe samples and a PerkinElmer Graphite Furnace Atomic Absorption Spectrometer (GFAAS) Model 5100 for all floor dust-wipe samples. However, a floor dust sample whose value was found to be 5 μg or greater by GFAAS are re-analyzed by FAAS and that value is reported.

Detailed specimen collection instructions are discussed in the NHANES Household Interview Procedures Manual, Chapter 7. This chapter specifies the procedure to be used for preparation of the window and floor, specimen collection, labeling, and conditions for specimen transport.

Additional dust samples (either window sill or floor) were taken in 5% of households as part of the quality control procedures. A field blank was also collected. Results from these quality control measures are not included as part of this data file.

For the year 2000, the floor samples (n=30) had a 99.8% (+/-2.1%) recovery at an average spike level of 75.31 (sd 14.29) μg. The window sill samples (n=29) revealed a 99.8% (+/-2.9%) recovery at an average spike level of 74.94 (sd 18.77)μg. This data is not available for 1999.

This data file includes the laboratory values as well as variables related to characteristics of the room where the samples were taken, and other factors relevant to data collection.

DCDINDEX

The variable identifies the index child designated for dust collection. Descriptive data about the home environment and the dust samples were collected for one child in the household. In homes where more than one child aged 1-5 years resided, the descriptive and laboratory data for the index child were assigned to all other children in the age group.

DCDSTAT

This variable indicates which samples are available. In some households, only a single sample (either window sill or floor) was taken. This variable was derived based on final results from the laboratory.

DCD030

The room where the sample was taken was most often the same room where the child spent most of his or her time in the home. In editing this variable, some responses from the "other" category were re-coded to pre-existing categories, and additional categories were created.

DCD070A

Carpet in room selected for sample. Response categories ordering from the original question were reordered for purposes of clarification and consistency.

It is advised that this data file should be combined with additional years of data because data are available on a small subset of the survey population. This data file was designed to be used primarily at the SP level with other data collected in the MEC. Please note, data were retained for persons who took part in the household interview (including dust collection) but were not examined at the MEC.

LBXDFS

Floor sample, lead dust result (μg/sq ft), by GFAAS. All floor dust results are derived from a 1 square foot area, the size of the template used for the sample collection. If a floor sample was collected but the result is missing for LBXDFS, use LBXDFSF. Use LBDDFSLC, the laboratory comment code, to determine values below the limit of detection.

LBXDFSF

Floor sample, lead dust result μg/sq ft) by FAAS. All floor dust results are derived from a 1 square foot area, the size of the template used for the sample collection. If a floor sample was collected but the result is missing for LBXDFSF, use LBXDFS. Use LBDD3LC, the laboratory comment code, to determine values below the limit of detection.

LBXDDWS

Window sill sample, lead dust result (μg/sq ft). All window sill dust results were calculated based on the measured length and width of the window sill area. Use LBDDWSLC, the laboratory comment code, to determine values below the limit of detection.