In what researchers are calling a first, a new analysis suggests
that the greater a woman's exposure to a type of common chemical compound
called PFCs, the greater her risk for developing osteoarthritis.
Researchers did not find a similar risk among men regarding
these chemicals, which are now found in everything from nonstick cookware to
take-out containers and carpeting.
Osteoarthritis, the most common type of arthritis, causes
pain and stiffness and involves degeneration of the cartilage in the joints.
And the study authors stressed that while their investigation
identified a robust link between osteoarthritis and exposure to two specific
PFC chemicals - known as PFOA and PFOS - for now the finding can only be
described as an association, rather than a cause-and-effect relationship.
"But we did find a clear and strong association between
exposure to [these] compounds and osteoarthritis, which is a very painful
chronic disease," said study lead author Sarah Uhl, who conducted the
study while working as a researcher at the Yale School of Forestry and Environmental
Studies in New Haven, Conn.
"This adds to the body of information that we have
suggesting that these highly persistent synthetic chemicals are of concern when
it comes to the public health," she said.
Uhl noted that exposure to PFCs is nearly universal, given
their inclusion in a vast array of products to enable (among other things) the
grease-proofing of food packaging, waterproofing of rain gear, and textile
stain protection.
What the study found
Previous research has linked PFC exposure to a higher risk
for the premature onset of menopause in women, higher levels of "bad"
LDL cholesterol in men and women, and reduced effectiveness of routine
vaccinations among children.
To explore a potential PFC-osteoarthritis connection, the
authors looked at PFOA and PFOS exposure data collected between 2003 and 2008
by the US National Health and Nutrition Examination Survey.
The analysis covered more than 4000 men and women between
the ages of 20 and 84 for whom osteoarthritis status information was available.
The team found "significant associations" between
osteoarthritis incidence and exposure to PFOA or PFOS among women but not men.
Women exposed to the highest levels of either chemical
seemed to face up to nearly double the risk for developing osteoarthritis,
compared to women exposed to the lowest levels.
The osteoarthritis-PFC connection also appeared to be
stronger among younger women (between 20 and 49) than among older women
(between 50 and 84). But the team said more follow-up research is needed to
confirm the observation.
While the biological reason behind the potential connection
remains unclear, the team suggested that the chemicals may have a particularly
profound impact on hormonal balances for women.
"Our hormone systems are incredibly delicate and can be
thrown off by tiny doses of hormone-disrupting chemicals," Uhl said.
"And processes like inflammation and cartilage repair are associated with
our hormones, and are also associated with osteoarthritis."
Whatever the culprit, Uhl cautioned that the problem is
likely to persist for years to come despite a safety-driven downward trend in
global PFOA/PFOS use.
"Once they get into the environment they just don't go
away," she noted. "In people, they last years. So even if we were to
reduce the use of these chemicals right away, they're still going to be around
and in our bodies for a long time," she explained.
"Not being exposed is not an option, which is
frustrating," Uhl added. "But as consumers, I would say that one of
the best things to do is to lead a healthy lifestyle, and get exercise and eat
well. Because we're finding that those steps can reduce susceptibility to
factors that are outside our control."
More research needed
Commenting on the study, Dr Joseph Guettler, an orthopedic
surgeon and sports medicine specialist at Beaumont Hospital in Royal Oak,
Mich., suggested that PFC exposure should be put in context as one of a wide
number of variables that can potentially drive osteoarthritis risk.
"There's genetics, weight and obesity, and previous
injuries," he noted. "There are some people who are biomechanically
built in a certain way that predisposes them. And then others with certain
[jobs] who put a lot of wear and tear on their body," Guettler pointed
out.
"And now this study seems to add an environmental
factor, PFCs, to the list of traditional risk factors," he continued.
"The fact that they didn't find this association among
men surprises me," Guettler added. "They hypothesize that this may be
due to hormonal differences, but I would expect that the main mechanism for
PFCs influencing osteoarthritis would be through their effect on the
inflammatory process. Because PFCs have been linked to inflammation, and we are
well aware that inflammation has a significant negative impact on cartilage. So
there definitely needs to be more research."
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