With global warming comes a rash of poison ivy*

By Anita Manning, USA TODAY

Poison ivy loves global warming.

As carbon dioxide levels have risen, the nasty weed has grown more
vigorously and is producing more of the evil oil that makes people itch,
says a report in this month's issue of the journal Weed Science.

Lead author Lewis Ziska, an ecologist in the U.S. Department of
Agriculture's office on crop systems and global change in Beltsville,
Md., grew poison ivy in chambers under conditions that matched CO-2
levels as they were in 1950, about 300 parts per million (ppm), and as
they are today, about 400 ppm. "Even with the small change (in CO-2
level) that has already occurred, poison ivy was able to double in
size," he says.

Poison ivy grown at CO-2 levels up to 600 ppm, the predicted level at
the end of this century, were even bigger, tripling the 1950s-size
plants, the researchers report.

The work is a continuation of a study published last year that found
that poison ivy plants in a wooded area at a Duke University research
center that were exposed to high CO-2 levels grew faster than other
weeds. The plants also produced a more concentrated amount of urushiol,
the substance in poison ivy leaves that causes an allergic reaction in
about 80% of the population.

Ziska says removing some of the leaves, to simulate natural nibbling by
deer and rabbits, did nothing to impede growth. Higher CO-2 levels and
higher temperatures that make for a longer growing season are "a win-win
for poison ivy … but not necessarily for human health," Ziska says.

Every summer, doctors see poison ivy rashes, which usually can be
treated with anti-itch creams or lotions. But Robin Gehris, a pediatric
dermatologist at Children's Hospital of Pittsburgh, says she has never
seen so many severe cases as she has this year. That includes five cases
of "black dot" poison ivy, an unusual form of the familiar rash that
begins with black spots caused by the oxidation of the plant oil on the
skin and develops into a fiercely itchy rash.

Caused by common poison ivy, it may result from a greater-than-usual
exposure to the oil on the leaf surface, Gehris says. Patients "end up
with a more nasty dermatitis," she says, so for doctors, the black dots
"identify that select population of patients that need to be treated
more aggressively."

One of Gehris' patients is Clayton Coppola, 7, of West Homestead, Pa.
This month, while playing near a local athletic field, he, his brother,
Tyler, 5, and a 7-year-old neighbor picked blackberries and pulled on
ivy weeds growing on a fence. Within minutes, says Dawn Coppola, his
mother, the boys sprouted black dots on their faces. "We thought it was
oil on the fence or blackberry juice," she says.

She tried to wash the dots off or scrape them with her fingernail. She
even tried mascara remover, but the spots wouldn't go away. She took the
boys to a doctor, who was puzzled and e-mailed a photo to Gehris at
Children's Hospital.

Tyler's and the neighbor boy's black spots and poison ivy rashes, though
worse than average poison ivy cases, have eased.

Clayton, who had about 10 black dots, still has a fierce poison ivy rash
all over his body and is being treated with steroids. His mother says he
"looks like he got stung by a thousand bees."

FIGHT THE ITCH

If you're exposed to poison ivy:

•Wash area with alcohol; rinse with water.

•Wash clothes and wipe shoes with alcohol and water.

•If itchy blisters erupt, wet compresses, oral antihistamines and
over-the-counter anti-itch creams and lotions may help.

•Severe rash may require a prescription corticosteroid; see your doctor.

Source: Food and Drug Administration