Biomonitoring - Cotinine
In nonsmokers, cotinine is a marker of exposure to environmental tobacco smoke (ETS), commonly referred to as secondhand smoke.
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Indicators
Cotinine in nonsmoking children ages 3 to 17 years: Median and 95th percentile concentrations in blood serum, 1988-2020 (Indicator B4)*
*The data for 2020 only go through March 2020 because the NHANES program suspended field operations due to the COVID-19 pandemic. As a result, data collection for the 2019–2020 cycle was not completed.
Web update: 2023
Click to open in new window | Tips for selecting and filtering data (pdf) | Download in Excel
- Data for this indicator are obtained from an ongoing continuous survey conducted by the National Center for Health Statistics.
- Survey data are representative of the U.S. civilian noninstitutionalized population.
- Cotinine is measured in blood samples obtained from individual survey participants.
- The median level of cotinine measured in blood serum of nonsmoking children ages 3 to 17 years dropped from 0.25 ng/mL in 1988–1991 (ages 4 to 17 years) to 0.02 ng/mL in 2017–2020, a decrease of 92%. This decreasing trend was statistically significant.
- Cotinine values for children at the 95th percentile decreased by 34% from 1988–1991 to 2017–2020. This trend was also statistically significant.
- Children at the 95th percentile of cotinine levels had much higher levels than those at the median. In 1988–1991, the 95th percentile cotinine level (3.2 ng/mL) was 13 times the median level (0.25 ng/mL); in 2017–2020, the 95th percentile cotinine level (2.1 ng/mL) was 105 times the median level (0.02 ng/mL).
- In every period measured except 2013-2014, children at the 95th percentile had higher levels of cotinine in their blood than women at the 95th percentile. (Compare with Indicator B5.)
- In 2015–2020, median concentrations of cotinine in blood for nonsmokers were approximately 0.10 ng/mL for Black non-Hispanic children, 0.03 ng/mL for White non- Hispanic children, 0.02 ng/mL for Mexican-American children, and 0.02 ng/mL for children of “All Other Races/Ethnicities.” The differences between Black non-Hispanic children and the other race/ethnicity groups were all statistically significant. (See Indicator B4a.)
- In 2015–2020, the median concentration of cotinine in blood serum for nonsmoking children living below the poverty level (0.07 ng/mL) was about 4 times the median for nonsmoking children living at or above the poverty level (0.02 ng/mL). The differences between income groups were not statistically significant after accounting for differences by age, sex, and race/ethnicity. Black non-Hispanic children living below poverty level had higher concentrations of cotinine compared with other race/ethnicity groups, but the estimate is not reliable enough to assess statistical significance. (See Indicator B4a.)
- In 2015–2020, 95th percentile concentrations of cotinine in blood for nonsmokers were 1.9 ng/mL for White non-Hispanic children and 3.0 ng/mL for Black non-Hispanic children. The differences between levels for these race/ethnicity groups were statistically significant. (See Indicator B4b.)
Cotinine in nonsmoking women ages 16 to 49 years: Median and 95th percentile concentrations in blood serum, 1988-2020 (Indicator B5)*
*The data for 2020 only go through March 2020 because the NHANES program suspended field operations due to the COVID-19 pandemic. As a result, data collection for the 2019–2020 cycle was not completed.
Web update: 2023
Click to open in new window | Tips for selecting and filtering data (pdf) | Download in Excel
- Data for this indicator are obtained from an ongoing continuous survey conducted by the National Center for Health Statistics.
- Survey data are representative of the U.S. civilian noninstitutionalized population.
- Cotinine is measured in blood samples obtained from individual survey participants.
- The median level of cotinine measured in blood serum of nonsmoking women of child-bearing age dropped from 0.21 ng/mL in 1988–1991 to 0.02 ng/mL in 2017–2020, a decrease of 90%. This decreasing trend was statistically significant.
- Cotinine values for women at the 95th percentile decreased by 46% from 1988–1991 to 2017–2020. This trend was also statistically significant.
- Women at the 95th percentile of cotinine levels had much higher levels than those at the median. In 1988–1991, the 95th percentile cotinine level (2.6 ng/mL) was 12 times the median level (0.21 ng/mL); in 2017–2020, the 95th percentile cotinine level (1.4 ng/mL) was 70 times the median level (0.02 ng/mL).
- In 2015–2020, median concentrations of cotinine in blood for nonsmoking women were approximately 0.09 ng/mL for Black non-Hispanic women, 0.02 ng/mL for White non- Hispanic women, and 0.01 ng/mL for Mexican-American women. The differences between Black non-Hispanic women and Mexican-American women were statistically significant. (See Indicator B5a.)
- Cotinine values at the 95th percentile were more than four times higher for nonsmoking women living below the poverty level (5.0 ng/mL) than for nonsmoking women living at or above the poverty level (1.1 ng/mL) in 2015–2020. The differences between between income groups were not statistically significant after accounting for differences by age, sex, and race/ethnicity (See Indicator B5b.)
About the Cotinine Indicators
Indicators B4 and B5 present information about cotinine levels measured in children and women. In nonsmokers, cotinine is a marker of exposure to environmental tobacco smoke (ETS), commonly referred to as secondhand smoke. The data are from a national survey that collects blood specimens from a representative sample of the population every two years, and then measures the concentration of various contaminants in the blood. These indicators focus on both children and women of child-bearing age because of concern for potential adverse effects in children exposed to ETS and in children born to women who have been exposed to ETS. Note that the data for 2020 only go through March 2020 because the NHANES program suspended field operations due to the COVID-19 pandemic. As a result, data collection for the 2019–2020 cycle was not completed.
ETS is a complex mixture of gases and particles and includes smoke from burning cigarettes, cigars, and pipe tobacco, as well as exhaled smoke. Children can be exposed to ETS in their homes or in places where people are allowed to smoke, such as some restaurants in some locations throughout the United States.
According to the U.S. Surgeon General, there is no safe level of exposure to ETS, and breathing even a small amount can be harmful to human health. The Surgeon General has concluded that exposure to ETS causes sudden infant death syndrome (SIDS), acute lower respiratory infections, ear problems, and more severe asthma in children. Exposure to ETS causes respiratory symptoms and slows lung growth in children. The exposure of a pregnant woman to ETS can also be harmful to her developing fetus. The Surgeon General has determined that exposure of pregnant women to ETS causes a small reduction in mean birth weight and the evidence is suggestive (but not sufficient to infer causation) of a relationship between maternal exposure to environmental tobacco smoke during pregnancy and preterm delivery.
Indicators B4 and B5 present cotinine levels measured in blood serum of women and children from the National Health and Nutrition Examination Survey (NHANES) as a marker of exposure to ETS.
More information about cotinine and Indicators B4 and B5 is provided in the Cotinine section of America's Children and the Environment, Third Edition (pdf) .
Methods - Cotinine
The National Center for Health Statistics, a division of the Centers for Disease Control and Prevention, conducts the National Health and Nutrition Examination Surveys (NHANES), a series of U.S. national surveys of the health and nutrition status of the noninstitutionalized civilian population. Interviews and physical examinations are conducted with approximately 10,000 people in each two-year survey cycle. The survey measures cotinine levels in blood serum samples collected from NHANES participants.
Indicator B4 uses the NHANES data to present median and 95th percentile concentrations of cotinine measured in blood serum of nonsmoking children ages 3 to 17 years (ages 4 to 17 years for 1988-1994). Indicator B5 uses the NHANES data to present median and 95th percentile concentrations of cotinine measured in blood serum of nonsmoking women ages 16 to 49 years. Both indicators present cotinine levels for non-tobacco-users only.
- Detailed Methods for Indicators B4 and B5 (pdf)
- Metadata for National Health and Nutrition Examination Survey (NHANES)
Supplemental Data Tables
The following data tables are available to view and export for analysis and visualization. Right click the table for exporting options.
Related Links
- Centers for Disease Control and Prevention (CDC): Health Effects of Secondhand Smoke
- Centers for Disease Control and Prevention (CDC): National Report on Human Exposure to Environmental Chemicals
- National Cancer Institute (NCI): Secondhand Smoke and Cancer
- National Toxicology Program (NTP): Tobacco-Related Exposures
- U.S. EPA: Health Effects of Exposure to Secondhand Smoke