Trend at a glance
Evidence from multiple sources -- including a recent Sightline analysis of
Cascadians' breastmilk -- makes it clear that the residents of Cascadia carry
a thin soup of synthetic toxic chemicals in their bodies.
Many of these compounds simply did not exist, or were present in incredibly minute quantities, before the 20th century.
But determining contamination trends will require a comprehensive, long-term system
of testing Cascadia's human residents for the presence of toxic chemicals.
At present, no such program exists.
Updated January 2009.
(Click for more information on Sightline's pollution research.)
More about pollution
What the pollution indicator measures and why
The Scorecard's pollution indicator measures the concentration of two types of
long-lived toxic chemicals -- PCBs and PBDEs -- in human bodies, as manifested in mother's milk.
These compounds are considered "persistent bioaccumulative toxics":
they are harmful to living things, they break down slowly, and they build up over time in living tissue.
Read more 
Both PCBs and PBDEs can harm neurological development and the immune system of laboratory animals.
Long-term studies have found that children who were exposured to high levels of PCBs in the womb
can suffer from subtle learning and memory deficits.
And high levels of PBDEs and PCBs have
even been correlated with reduced genital size in polar bears.
Although the Cascadia Scorecard tracks only PCBs and PBDEs, other compounds are of concern as well.
For example, methyl mercury -- a hazardous form of mercury
-- can harm the nervous system, and is especially dangerous to
young children and developing fetuses. Some researchers estimate that as many as one in seven children
born in the United States have enough mercury in their blood to reduce their IQ.
Read less 
The target and why it was chosen
The Scorecard's target level for PBDEs is 1.3 parts per billion (as measured in fat), which was the median level in Japan in 2000.
(Click here for a chart of global PBDE levels.)
For PCBs the target level is 51 parts per billion, the lowest level found in any sample Sightline tested in 2004.
(Click to read about how the Scorecard works, including how targets are chosen.)
Long-term trends
Though banned in the 1970s, PCBs remain ubiquitous in soils, sediments, and living things.
Because the compounds are attracted to plant and animal fats, they concentrate at each successive link in the food chain,
reaching high levels in top predators such as orcas and humans.
Read more
PCBs were once prized by industry for their chemical stability
-- a quality that also makes them slow to degrade once released into the environment.
Levels of PCBs in the environment seem to have declined somewhat since their manufacture was banned.
But Washington's Puget Sound, with its history of industry and manufacturing, is considered a hot spot for PCB contamination.
In March 2006, the Washington Department of Health took the unusual step of warning consumers to
limit consumption of chinook salmon from Puget Sound to one meal per week, in part because of high levels of PCBs.
(The fish also contain high levels of mercury.)
Chinook tested from Puget Sound had up to six times more PCBs than chinook caught elsewhere on the West Coast.
PBDEs are chemical cousins of PCBs that until recently were used as flame retardants in furniture foams.
PBDE concentrations have been on the rise throughout most of the industrial world for decades,
with high (and rising) levels found in the bodies of North Americans.
(Click here for a chart of North American PBDE trends.)
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The results in detail
In 2004, Sightline investigated the levels of PCBs and PBDEs in Cascadians' bodies by
testing breastmilk samples from 40 first-time mothers with young infants.
The findings were alarming:
both compounds were present in every sample tested.
Among the 40 samples, the median (midpoint) concentration was
134 parts per billion of PCBs, and
50 parts per billion of PBDEs -- a level of PBDEs that is 20 to 40 times
higher than typically has been found in northern Europe and Japan.
Read more
Sightline tested
breastmilk, rather than blood, because human milk is high in the fats to which PCBs and PBDEs adhere;
because it can be collected noninvasively;
and because results from breastmilk tests can serve as a proxy for the toxic levels, or "body burdens," of similarly aged men and
nonbreastfeeding women.
Sightline's findings do not alter an important fact: breastmilk is far and away the healthiest food for infants.
Roughly one-third of the breastmilk samples Sightline tested had higher levels of PBDEs than PCBs,
suggesting that the health threats from PBDEs may gradually be overtaking those from PCBs.
And there's no firm evidence that PBDE contamination has plateaued.
A 2006 analysis of the blood of ten Washington residents also found PBDEs in every sample,
at concentrations comparable to those in the 2004 breastmilk samples.
Fortunately, North Americans have begun to take a more precautionary approach toward PBDEs.
The US Environmental Protection Agency reached an agreement the chemicals' manufacturers to halt production of the most
troublesome forms of the compounds.
In 2005 an Oregon bill banned the use of the most toxic forms of PBDEs in the state starting in 2006.
Likewise, Canada announced in 2006 that it would add all forms of PBDEs to its national list of toxic substances,
which may make them subject to additional regulations.
In Washington, the state health and ecology agencies recommended a near-total ban of the compounds,
and in early 2007 the Washington legislature voted overwhelmingly to follow those recommendations.
If the ban of PBDEs proves effective, concentrations of the compounds in human bodies will gradually wane.
That success may teach us to take greater initiative in combating toxics,
by requiring that potentially hazardous compounds be tested for safety before they are used widely.
Read less
PCB and PBDE levels, by region
Global PBDE levels
North American PBDE trends
