So, biomonitoring gives scientists
important information about the chemicals we’re exposed to and
how they affect our bodies. That information helps our
government and public health officials make more informed decisions. CDC conducts a survey every
2 years to assess the health and nutritional status of adults
and children in the U.S. It’s called the
National Health and Nutrition Examination Survey, or NHANES for short. Scientists at the Biomonitoring Program
use the NHANES survey results to gather exposure data,
or information about the levels of chemicals in people’s bodies.
Here’s how that works. First, scientists choose a sample —
a small group of people who participated in the NHANES survey —
to analyze. To reflect our diverse population
here in the United States, scientists make sure to
include people of different age groups, genders, and ethnicities.

Then, they study blood and
urine samples from this group of people to find out what
chemicals and how much of those chemicals are in their bodies. Finally, CDC publishes the results
in a report called the National Report on Human Exposure to
Environmental Chemicals and Updated Tables. This report is the most
comprehensive assessment ever made of human exposure to
environmental chemicals. The first version of the report,
published in March 2001, included exposure data about 27 chemicals. Additional reports followed in 2003, 2005, and 2009,
along with several report updates. Each report and update included
exposure data on more chemicals. The latest version includes
exposure data for more than 300 chemicals and includes
findings from 1999 to 2016. Here are a few of the chemicals
included in the report. All that biomonitoring data
has led to important policy changes that protect our nation’s health. For example, biomonitoring research
played an important role in reducing lead use in
the United States. People who are exposed to
high levels of lead can get lead poisoning, which may cause learning disabilities
and behavior problems. Very high levels of lead
in the body can cause seizures, coma, or even death. In 1981, the U.S. Environmental Protection Agency,
or EPA, was considering changing the law to allow more lead in gasoline.

But thanks in large part to
biomonitoring research, the EPA decided to restrict
the use of leaded gasoline instead. Here’s how it happened: The EPA’s research predicted that
leaded gasoline would have a limited impact on blood lead levels,
or the amount of lead people have in their bodies. But a CDC survey showed
that blood lead levels had dropped from 1976 to 1980
and that the drop tracked decreased use of lead in gasoline. Over that time period,
decreased use of lead in gasoline resulted from the
introduction of unleaded gasoline in the United States. More research showed similar
relationships between lead in gasoline and blood lead levels
in other countries. Based on this critical scientific evidence,
the EPA decided to restrict the use of leaded gasoline. And as remaining lead was
removed from gasoline, blood lead levels continued to decline. Removing lead from paint has also made
a big impact on lead levels in the U.S. By 1999, blood lead levels in children
ages 1 to 5 had fallen to historic lows. But we haven’t completely solved
the lead problem. While lead-based paint was banned
from use in housing in 1978, as many as 24 million older homes still
have lead paint or lead-contaminated dust.

And about 4 million of those are
home to young children, who are most likely to be affected
by lead poisoning. So, biomonitoring scientists continue to track
lead levels in Americans, helping us assess how well national programs aimed
at reducing or eliminating lead exposure are working. More information about blood lead levels
is available in CDC’s National Report on Human Exposure to Environmental
Chemicals and Updated Tables. Biomonitoring also helped us put
policies in place to reduce people’s exposure to secondhand smoke. Nicotine is the addictive chemical
used in tobacco products like cigarettes, vaping devices, and chewing tobacco. Even people who don’t smoke
or use other tobacco products might be exposed to nicotine
when they spend time in places where other people are smoking. This is called secondhand smoke,
and it can be harmful to people’s health. Cotinine is a substance that forms
in your body when you are exposed to nicotine. By measuring the levels of
cotinine in a person’s body, scientists can tell how much
nicotine they have been exposed to. CDC biomonitoring scientists developed
a way to measure very low levels of cotinine in people’s bodies.

They found that 88% of people
who didn’t smoke were exposed to secondhand smoke. And people who worked
around tobacco had even higher levels of cotinine in their bodies. This data inspired new laws
to restrict smoking in public buildings. When CDC measured cotinine levels
again in 1999 and 2000, they found that average
cotinine levels among people ages 3 and older had
decreased by more than 70%. That means people were exposed
to a lot less secondhand smoke. The 2006 Surgeon General’s Report
celebrated this dramatic reduction. However, there is still more
work to be done. Children’s cotinine levels are
still twice those of adults. And newer tobacco products
like e-cigarettes and vape pens could also present serious
health risks. Biomonitoring scientists continue to
track cotinine levels to assess how well efforts to reduce
secondhand smoke exposure are working.

For more information on cotinine levels,
see CDC’s National Report on Human Exposure to Environmental Chemicals
and Updated Tables..



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