Inorganic Mercury
Uncertainties exist regarding levels of exposure to methyl mercury from fish consumption and potential health effects resulting from this exposure. Past estimates of exposure to methyl mercury have been obtained from results of food consumption surveys and measures of methyl mercury in fish. Measures of a biomarker of exposure are needed for improved exposure assessments. Blood mercury levels will be assessed in two subpopulations particularly vulnerable to the health effects from mercury exposure: children 1–5 years old and women of childbearing age.
Blood measures of inorganic mercury will be important for evaluation of exposure from exposure to mercury in interior latex paints
Participants aged 1 year and older, who do not meet any of the exclusion criteria, are eligible.
Whole blood specimens are processed, stored, and shipped to the Division of Laboratory Sciences, National Center for Environmental Health, and Centers for Disease Control and Prevention for analysis.
Inorganic Mercury
Inorganic mercury in blood is measured using stannous chloride as a reductant, also utilizing microwave digestion. Mercury vapor (reduced from inorganic mercury compounds) is measured via the same quartz cell at 253.7 nm.
The difference between total and inorganic mercury represents the organic mercury in blood. Mercury analysis identifies cases of mercury toxicity. The main organs affected by mercury are the brain and kidneys. Psychic and emotional disturbances are the initial signs of chronic intoxication by elemental mercury vapor or salts. Parasthesia and neuralgia may develop. Renal disease, digestive disturbances, and ocular lesions can also develop. Kidney toxicity is an important consequence of exposure to mercury salts.
There were no changes to the equipment or lab site from the previous 2 years.
Read the General Documentation on Laboratory Data file for detailed data processing and editing protocols. The analytical methods are described in the Description of the Laboratory Methodology section.
One variables were created, from existing variables, and added to this data file. The formula for its creation is as follows:
The inorganic mercury in ug/L was converted to nmol/L by multiplying by 4.99.
Detection Limits
The detection limits were constant for the analytes in the data set. The variable named LBX___ provides the analytic result for that analyte. In cases, where the result was below the limit of detection, the value for that variable is the detection limit divided by the square root of two.
Read the General Documentation on Laboratory Data file for detailed quality control and monitoring protocols.
The analytical methods are described in the Description of the Laboratory Methodology section.
The analysis of laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES Household Questionnaire Data Files contain demographic data, health indicators, and other related information collected during household interviews. They also contain all survey design variables and sample weights for these age groups. The phlebotomy file includes auxiliary information such as the conditions precluding venipuncture. The household questionnaire and phlebotomy files may be linked to the laboratory data file using the unique survey participant identifier SEQN.
Exam sample weights should be used for analyses. Please refer to the Analytic Guidelines for further details on the use of sample weights and other analytic issues. The Analytic Guidelines are available on the NHANES website.
| Code or Value | Value Description | Count | Cumulative | Skip to Item |
|---|---|---|---|---|
| 0.35 to 14 | Range of Values | 1860 | 1860 | |
| 0.25 | First Below Detection Limit Fill Value | 6302 | 8162 | |
| 0.28 | Second Below Detection Limit Fill Value | 0 | 8162 | |
| . | Missing | 1145 | 9307 |
| Code or Value | Value Description | Count | Cumulative | Skip to Item |
|---|---|---|---|---|
| 1.75 to 69.86 | Range of Values | 1860 | 1860 | |
| 1.4 | First Below Detection Limit Fill Value | 0 | 1860 | |
| 1.25 | Second Below Detection Limit Fill Value | 6302 | 8162 | |
| . | Missing | 1145 | 9307 |
| Code or Value | Value Description | Count | Cumulative | Skip to Item |
|---|---|---|---|---|
| 0 | At or above the detection limit | 1860 | 1860 | |
| 1 | Below lower detection limit | 6302 | 8162 | |
| . | Missing | 1145 | 9307 |