Report on the Environment
Blood Cotinine Level
What are the trends in indoor air quality and their effects on human health?
The above question pertains to all 'Indoor Air' Indicators, however, the information on these pages (overview, graphics, references and metadata) relates specifically to "Blood Cotinine Level". Use the right side drop list to view the other related indicators on this question.
- Test your home for radon and have it fixed if radon is found at or above EPA's Action Level.
- If you are buying a new home, look for builders who use radon-resistant new construction.
- Pledge not to smoke in your home and car
- Talk to your children's teachers and day care providers about keeping the places where your children spend time free from second-hand smoke and radon.
- If you or someone you know have children in Head Start, work with your Head Start provider through the Care for Their Air campaign
Click to enlarge exhibit
Environmental tobacco smoke (ETS) contains a mixture of toxic chemicals, including known human carcinogens. Persistent exposure to ETS is associated with numerous health-related disorders or symptoms, such as coughing, chest discomfort, reduced lung function, acute and chronic coronary heart disease, and lung cancer (IARC, 2004; NTP, 2002; U.S. EPA, 1992; CDC, 2005). Children are at particular risk from exposure to ETS, which can exacerbate existing asthma among susceptible children and also greatly increase the risk for lower respiratory tract illness, such as bronchitis and pneumonia, among younger children (CDC, 2005). Younger children appear to be more susceptible to the effects of ETS than are older children (U.S. EPA, 1992).
Household ETS exposure is an important issue because many people, especially young children, spend much time inside their homes. Based on data reported from the 1994 National Health Interview Survey, the Department of Health and Human Services estimates that 27 percent of children age 6 years and younger are exposed to ETS in the home (U.S. DHHS, 2000).
Exposure to ETS leaves traces of specific chemicals in people’s blood, urine, saliva, and hair. Cotinine is a chemical that forms inside the body following exposure to nicotine, an ingredient in all tobacco products and a component of ETS. Following nicotine exposures, cotinine can usually be detected in blood for at least 1 or 2 days (Pirkle et al., 1996). Active smokers almost always have blood cotinine levels higher than 10 nanograms per milliliter (ng/mL), while non-smokers exposed to low levels of ETS typically have blood concentrations less than 1 ng/mL (CDC, 2005). Following heavy exposure to ETS, non-smokers can have blood cotinine levels between 1 and 10 ng/mL.
This indicator reflects blood cotinine concentrations in ng/mL among non-smokers for the U.S. population, age 3 years and older, as measured in the 1999-2000, 2001-2002, 2003-2004, 2005-2006, and 2007-2008 National Health and Nutrition Examination Survey (NHANES). NHANES is a series of surveys conducted by the Centers for Disease Control and Prevention’s (CDC’s) National Center for Health Statistics, designed to collect data on the health and nutritional status of the civilian, non-institutionalized U.S. population using a complex, stratified, multistage, probability-cluster design. Blood cotinine also was monitored in non-smokers age 4 years and older as part of NHANES III, between 1988 and 1994. CDC’s National Center for Environmental Health conducted the laboratory analyses for the biomonitoring samples. Beginning in 1999, NHANES became a continuous and annual national survey.
As part of the first phase of NHANES III (1988–1991), CDC estimated that the median blood cotinine level (50th percentile) among non-smokers in the general U.S. population was 0.20 ng/mL (Pirkle et al. 1996). In NHANES 1999–2000, the estimated median blood cotinine level among non-smokers nationwide had decreased to 0.06 ng/mL. During the most recent survey period (2007–2008), the estimated median blood cotinine levels for the U.S. population was 0.04 ng/mL (see Exhibit 2-57). This marks a 33 percent decrease from levels measured in 1999–2000 and an overall 80 percent decline since the NHANES III (1988–1991)–a consistent reduction over time that suggests a marked decrease in exposure to ETS.
Exhibit 2-57 shows the results of NHANES 1999–2008, by survey period, for different subpopulations. Similar decreasing trends in blood cotinine levels are observed between NHANES III (1988–1994) and the most recent 2007–2008 survey in each of the population groups defined by age, sex, and race/ethnicity (CDC, 2010). These data reveal three additional observations: (1) non-smoking males have slightly higher cotinine levels than females across survey periods; (2) of the ethnic groups presented, non-Hispanic blacks had the highest cotinine levels; (3) on average, people below the age of 20 have higher blood cotinine levels than people age 20 years and older.
Exhibit 2-58 shows the percentage of children between the ages of 4 and 17 with specified blood cotinine levels, for the total age group and by selected race and ethnicity breakdowns. Among the three subgroup populations presented, Mexican American children had the lowest percentage of blood cotinine levels greater than 1.0 ng/mL; this was evident for all three time periods displayed (10.7, 5.2, and 4.5 percent, respectively). Between 1988–1994 and 1999–2002, black, non-Hispanic children had the largest absolute decline of the three subgroups in the percentage of blood cotinine levels greater than 1.0 ng/mL, but that population also started off with the highest percentage above 1.0 ng/mL (36.6 percent). In 2003–2008, the percent of children with blood cotinine levels greater than 1.0 ng/mL decreased by 3.0, 0.7, and 2.4 percent among black, non-Hispanic, Mexican-American, and white, non-Hispanic, respectively, compared to 1999–2002 (Federal Interagency Forum on Child and Family Statistics, 2005; CDC, 2010).
- Because of the relatively small number of samples collected during any one calendar year, reporting the results in a two-year cycle (e.g., 1999–2000 or 2001–2002) may, in some cases, result in measures of central tendency that are unstable from one survey period to the next.
Data used for this indicator were generated with Stata statistical software utilizing the NHANES laboratory files available online in SAS® transport file format (CDC, 2010). Some of the data used for Exhibit 2-58 were extracted from a report by the Federal Interagency Forum on Child and Family Statistics (2005).
CDC (Centers for Disease Control and Prevention). 2010. National Center for Health Statistics, National Health and Nutrition Examination Survey. Accessed January 2010. http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm
CDC. 2004. NHANES analytic guidelines. June 2004 version. Accessed October 21, 2005. http://www.cdc.gov/nchs/data/nhanes/nhanes_general_guidelines_june_04.pdf
CDC. 2002. NHANES 1999-2000 addendum to the NHANES III analytic guidelines. Last update August 30, 2002. Accessed October 11, 2005. http://www.cdc.gov/nchs/data/nhanes/guidelines1.pdf
Federal Interagency Forum on Child and Family Statistics. 2005. America’s children: Key national indicators of well-being, 2005. Washington, DC: U.S. Government Printing Office. Accessed December 20, 2005. http://www.childstats.gov/pdf/ac2005/ac_05.pdf
IARC (International Agency for Research on Cancer). 2004. IARC working group on the evaluation of carcinogenic risks to humans. Evaluation of carcinogenic risks to humans, volume 83: Tobacco smoke and involuntary smoking. Lyon, France.
NTP (National Toxicology Program) 2002. Report on carcinogens, 10th edition.
Pirkle, J.L., K.M. Flegal, J.T. Bernert, D.J. Brody, R.A. Etzel, K.R. Maurer. 1996. Exposure of the U.S. population to environmental tobacco smoke: The third national health and nutrition examination survey, 1988 to 1991. J. Amer. Med. Assoc. 275:1233-1240.
U.S. DHHS (United States Department of Health and Human Services). 2000. Healthy people 2010. Second edition. Washington, DC: U.S. Government Printing Office http://www.healthypeople.gov/Document/HTML/Volume2/27Tobacco.htm#_Toc489766224
U.S. EPA (United States Environmental Protection Agency). 1992. Respiratory health effects of passive smoking: Lung cancer and other disorders. Washington, DC.
|Blood Cotinine Level|
|2.||ROE Question(s) This Indicator Helps to Answer|
|This indicator is used to help answer two ROE questions: "What are the trends in indoor air quality and their effects on human health?" and "What are the trends in exposure to environmental contaminants including across population subgroups and geographic regions?"|
This indicator describes the presence of cotinine in the blood of the U.S. population from 1999 to 2008. Blood cotinine levels from this period are also compared to those measured during earlier surveys (1988 to 1991). Blood cotinine is a chemical that forms inside the body after exposure to tobacco smoke. Looking at the amount of cotinine in the blood of non-smokers provides a good indication of exposures to environmental tobacco smoke and helps show changes over time and differences across subpopulations.
The data used for this indicator represent blood samples collected from a subset of study participants during the continuous (1999-2008) National Health and Nutrition Examination Survey (NHANES) and analyzed for cotinine. Historical NHANES III data are also considered, which covered the period 1988 to 1994. The Centers for Disease Control and Prevention's (CDC's) National Center for Environmental Health (NCEH) conducted the laboratory analyses.
The underlying laboratory data are available online in SAS® transport file format, along with the questionnaires and related documentation, at: http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm.
For the most part, individual level data are available, but data access limitations exist for some variables due to confidentiality issues. Disclosure risks and issues pertaining to confidentiality protection prevent NCHS from releasing all of the NHANES demographics variables publicly. Additional information may be publicly accessible through the NCHS Research Data Center (RDC). The RDC Web site has information about special request data files. Refer to the
NHANES 2007-2008 Data Documentation, Codebook, and Frequencies Demographic Variables and Sample Weights (DEMO_E) for additional information:
The NHANES III (1988-1994) data shown in Exhibit 2-58 were extracted from the Federal Interagency Forum on Child and Family Statistics (2005). NHANES III collected data on serum cotinine levels for children ages 4 and older, while the continuous NHANES (beginning in 1999) provided cotinine data for children 3 years and older, which is the reason the exhibit displays the age grouping 4-17 years.
NHANES is a series of surveys conducted by CDC's National Center for Health Statistics that is designed to collect data on the health and nutritional status of the civilian, non-institutionalized U.S. population. Blood samples were collected from a random sample of NHANES participants and are intended to provide estimates for the U.S. population. Participants are selected through a complex statistical process using the most current Census information, meaning that NHANES divides the United States into communities and neighborhoods, and neighborhoods and housing units are selected at random (CDC, 2010). This indicator is based on a national probability-based sampling design and is deemed of sufficient quality for generalization to the nation.
The survey represents a random sample of participants and is not designed to select or exclude participants on the basis of their potential for low or high exposure to a chemical, nor does the design permit examination of exposure levels by locality, state, or region; seasons of the year; proximity to sources of exposure; or use of particular products (CDC, 2009). However, NHANES is designed to provide statistically representative national averages. NHANES data provide a snapshot of the health and nutrition of the U.S. population. As a result, survey participants are from a broad range of age groups and racial/ethnic backgrounds, and each participant represents approximately "50,000 other U.S. residents" (CDC, 2010).
Beginning in 1999, NHANES became a continuous and annual survey. The sampling plan for each year follows a complex, stratified, multistage, probability-cluster design to select a representative sample of the civilian, non-institutionalized population. Every year, approximately 7,000 individuals of all ages are interviewed in their homes; of these, approximately 5,000 complete the health examination component of the survey. Data are released in 2-year cycles. The samples for 1999-2000; 2001-2002; 2003-2004; 2005-2006; and 2007-2008 surveys were used for this analysis.
To produce more reliable statistics (i.e., to enable the detection of meaningful differences between populations), the sampling methodology is purposely designed to oversample selected subgroups. For example, 1999-2006 surveys included over-samples of low-income persons, adolescents (12- to 19 years), older Americans (60 years or older), African Americans, Mexican Americans, and pregnant women. Oversampling schemes can change, however, across survey periods. Beginning in 2007, oversampling of pregnant women and adolescents was discontinued to enable oversampling of the Hispanic populations instead of just the Mexican American population.
CDC presents the measurements produced by NHANES for this indicator in its "Second National Report on Human Exposure to Environmental Chemicals" (CDC, 2003), "Third National Report on Human Exposure to Environmental Chemicals" (CDC, 2005), and "Fourth National Report on Human Exposure to Environmental Chemicals" (CDC, 2009).
Specimen Collection and Analysis
Blood serum specimens were collected from survey participants aged 3 years or older in NHANES 1999-2008 and analyzed for cotinine, and 4 years or older for NHANES III (1988-1994).
Serum cotinine is measured by an isotope dilution high performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometric (ID HPLC-APCI MS/MS) method. Briefly, the serum sample is spiked with methyl-D, cotinine as an internal standard, and following an equilibration period, the sample is applied to a basified solid phase extraction column. Cotinine is extracted off the column with methylene chloride, the organic extract is concentrated, and the residue is injected onto a short, C18 HPLC column. The eluant from these injections is monitored by APCI-MS/MS, and the m/z 80 daughter ion from the m/z 177 quasi-molecular ion in quantitated, along with additional ions for the internal standard, for the external standard, and for confirmation. Cotinine concentrations are derived from the ratio of native to labeled cotinine in the sample by comparisons to a standard curve. See the description of laboratory procedures used for cotinine at http://www.cdc.gov/nchs/data/nhanes/nhanes_01_02/l06_b_met_cotinine.pdf (24 pp, 344K , About PDF). The unit of analysis used for this indicator was nanograms per milliliter (ng/mL) (http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/COTNAL_E.htm).
Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory Procedures Manual (LPM) (CDC, 2001). Each chapter in the LPM specifies the procedures to be used for collecting, labeling, processing, preserving, and transporting specimens for each method used in the survey. Refer to the following data sources for specific information regarding data collection and processing: http://www.cdc.gov/nchs/data/nhanes/blood.pdf (24 pp, 75K) and http://www.cdc.gov/nchs/data/nhanes/LAB1-6.pdf (245 pp, 2.2MB).
The Addendum to the NHANES III for the 1999-2000 data set and the NHANES Analytic Guidelines June 2004 Version outline the sampling design and recommend analytic procedures. See http://www.cdc.gov/nchs/data/nhanes/guidelines1.pdf (28 pp, 371K); http://www.cdc.gov/nchs/data/nhanes/nhanes3/nh3gui.pdf (49 pp, 182K); and http://www.cdc.gov/nchs/data/nhanes/nhanes_general_guidelines_june_04.pdf (6 pp, 28K).
Details of the design and content of each survey and the public use data files are available at: http://www.cdc.gov/nchs/nhanes.htm.
NHANES analytic and reporting guidelines are outlined in: http://www.cdc.gov/nchs/data/nhanes/nhanes_03_04/nhanes_analytic_guidelines_dec_2005.pdf (14 pp, 48K).
Survey-specific documentation can be found at:
NHANES 2007–2008 public data general release file documentation: http://www.cdc.gov/nchs/nhanes/nhanes2007-2008/generaldoc_e.htm
NHANES 2005–2006 public data general release file documentation: http://www.cdc.gov/NCHS/data/nhanes/nhanes_05_06/general_data_release_doc_05_06.pdf (7 pp, 41K)
NHANES 2003–2004 public data general release file documentation: http://www.cdc.gov/nchs/data/nhanes/nhanes_03_04/general_data_release_doc_03-04.pdf (7 pp, 52K)
NHANES 2001-2002 public data general release file documentation: http://www.cdc.gov/nchs/data/nhanes/nhanes_01_02/general_data_release_doc.pdf (6 pp, 49K)
NHANES 1999-2000 public release data release file documentation: http://www.cdc.gov/nchs/data/nhanes/gendoc.pdf (6 pp, 101K)
NHANES public use data files were downloaded from the CDC National Health Statistics Center Web site (http://www.cdc.gov/nchs/nhanes.htm). Compilation and statistical queries of NHANES data were done in strict accordance with the data and analytic guidance provided by CDC (CDC, 2006).
No extrapolation methods were used to transform the data. NHANES selects a representative sample of the civilian, non-institutionalized population in the United States using a complex, stratified, multistage, probability-cluster design. The NHANES 1999-2004 survey is designed to give an annual sample that is nationally representative.
|9.||Quality Assurance and Quality Control|
NHANES data undergo rigorous quality control and quality assurance procedures and all protocols meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed quality control and quality assurance instructions are discussed in the NHANES Laboratory Procedures Manual (LPM) (CDC, 2001). Quality assurance activities are conducted before data collection and consist of equipment calibration and training. Quality control activities occur during data collection/processing and consist of automated software edits, data analysis of technician performance, and analytic processing.
In order to ensure the utility of its statistical and analytic information products, NCHS, which oversees NHANES, conducts independent research and consults with experts in areas such as data collection, data analysis, and a variety of substantive topics and issues. NCHS reviews the quality (including the objectivity, utility, and integrity) of information before it is released and treats information quality as integral to every step of the development of information. NCHS assures the security of its statistical and analytic information products through the enforcement of rigorous controls that protect against unauthorized access to the data, revision or corruption of the data, or unauthorized use of the data. See NCHS Guidelines for Ensuring the Quality of Information Disseminated to the Public for more information: http://www.cdc.gov/nchs/about/policy/quality.htm.
This indicator simply shows that exposure to environmental tobacco smoke (ETS) has occurred. Cotinine is a major metabolite of nicotine and is currently regarded as the best biomarker in active smokers and in non-smokers exposed to ETS. While non-smokers exposed to low levels of ETS typically have blood concentrations less than 1 ng/mL, those exposed to heavy exposure can have blood cotinine levels between 1 and 10 ng/mL. Active smokers almost always have blood cotinine levels higher than 10 ng/mL, and sometimes higher than 500 ng/mL. As reported in CDC's 2009 "Fourth National Report on Human Exposure to Environmental Chemicals" (http://www.cdc.gov/exposurereport/), the measurement of an environmental chemical in a person's blood or urine does not by itself mean that the chemical has caused or will cause harmful effects.
|11.||Comparability Over Time and Space|
The dataset is generally comparable over time and space. As a national survey, NHANES has a set of standardized, nationwide procedures. Although the survey became continuous in 1999, this change only reduced the dataset's variability; data before and after this change are still generally comparable.
|12.||Sources of Uncertainty|
Content under review.
|13.||Sources of Variability|
Because of the relatively small sample size for any 1-year period, analytical data for just one or two survey participants may be weighted heavily and greatly influence the mean value reported. To increase precision and statistical reliability, two or more 2-year cycles of the continuous NHANES data across calendar years are combined, increasing the sample size and utility of the indicator.
The continuous NHANES is considered nationally representative, but it is subject to the limits of increased sampling error due to 1) the smaller number of individuals sampled in the annual sample and 2) the smaller number of PSUs available for each annual sample. Therefore, the sample size for any 1-year period is relatively small, possibly resulting in large variability for U.S. population estimates, especially those for narrowly defined demographic groups or other specific subgroup analyses. Also, because the number of geographic sites sampled each year is small and environmental exposures may vary geographically, national estimates based on one year of data may be highly variable.
For the continuous NHANES, the first stage of selection was the PSU-level. The PSUs were defined as single counties. For a few PSUs, the county population was too small and those counties were combined with geographically contiguous counties to form a PSU. The continuous NHANES sample is selected from a relatively small number of PSUs compared to NHANES III. Because of the small number of PSUs, variance estimates that account for the complex design may be relatively unstable and introduce a higher level of uncertainty into the annual estimates.
A further description of survey design, sample weights, and variance estimation measurements associated with the continuous NHANES data sets are available at: http://www.cdc.gov/nchs/data/nhanes/guidelines1.pdf (28 pp, 371K) and http://www.cdc.gov/nchs/data/nhanes/nhanes_general_guidelines_june_04.pdf (6 pp, 28K).
No trend analysis has been conducted on this dataset.
Limitations to this indicator include the following:
CDC (Centers for Disease Control and Prevention). 2010. National Center for Health Statistics (NCHS) National Health and Nutrition Examination Survey: Welcome NHANES participants. Accessed May 2010. http://www.cdc.gov/nhanes/.
CDC. 2009. Fourth national report on human exposure to environmental chemicals. http://www.cdc.gov/exposurereport.
CDC. 2006. NHANES analytic and reporting guidelines: The National Health and Nutrition Examination Survey (NHANES). Last update: December 2005. Last correction: September 2006. http://www.cdc.gov/nchs/data/nhanes/nhanes_03_04/nhanes_analytic_guidelines_dec_2005.pdf (14 pp, 48K).
CDC. 2005. Third national report on human exposure to environmental chemicals.
CDC. 2003. Second national report on human exposure to environmental chemicals.
CDC. 2001. National Health and Nutrition Examination Survey laboratory procedures manual. http://www.cdc.gov/nchs/data/nhanes/LAB1-6.pdf (245 pp, 2.2MB).
Federal Interagency Forum on Child and Family Statistics. 2005. America's children: key national indicators of well-being, 2005. Washington, DC: U.S. Government Printing Office. Accessed December 20, 2005. http://www.childstats.gov/pdf/ac2005/ac_05.pdf (195 pp, 2.64MB).
Korn, E.L., and B.I. Graubard. 1998. Confidence intervals for proportions with small expected number of positive counts estimated from survey data. Survey Methodology 24:193-201.
StataCorp. 2009. Stata Statistical Software: Release 11. College Station, TX: StataCorp LP.