Date: Mon, 1 Feb 1999 15:48:58 -0500 From: "Mellard, David" <dam7@cdc.gov> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg288$foo@default> Subject: allergies and cp's
> There is something that is strange to me...
> >When I'm working in my greenhouse and I'm touching a carnivorous plant
> >with enzymes (like Drosera and Pinguicula) than there appears (afer half
> >an hour) red spots on my skin. I know for sure that the red spots are
> >from the enzymes of my plants. The "strange" thing is that, when I touch
> >an Ibicella, there also appears red spots on my skin... Aren't that
> >"digesting" enzymes?
>
Years ago, detergent manufacturers had to remove enzymes from their product
because some people developed an allergic reaction to the enzymes in the
soap. If I remember correctly, allergic reactions went beyond dermatitis
and involved the pulmonary system in some people. That happened because in
addition to the skin contact people were more likely to breathe the soap in
while dispensing it. It would not surprise me if some people developed an
allergic skin reaction to the digestive enzymes in plants.
The literature is full of examples of allergic skin reactions to plant
products.
Two examples are poison ivy and poison oak. One must first have an initial
skin contact with a plant, which induces the sensitivity, but does not
produce symptoms. However, subsequent contact once you are sensitized is
needed to produce symptoms. Usually five days to three weeks after contact
are needed to develop a skin reaction, although symptoms can appear in 12 to
48 hours for poison ivy and poison oak. It's the low molecular weight
compounds in the plants sap (called haptens) that react with enzymes on your
skin to produce the reactive antigen that induces the allergic response on
the skin. Only skin areas that actually touch the plant will develop a
reaction, plus those areas where you may mechanically move the hapten or
antigen once things start to itch. The palms are less likely to show a
reaction because the thicker skin affords more protection than say the back
of the hand and arms.
Plants can also cause contact urticaria, which can have an immunologic or
nonimmunlogic component to the response. An example of an nonimmunologic
contact urticaria is being stuck by nettles, which inject chemicals (for
example, acetylcholine, histamine, and serotonin) through the plant's hair.
The American ladyslipper (Cyp reginae) is another example. Urticaria is
characterized by hives and inflammation (redness) of the skin. Certain
edible vegetables can cause an allergic urticaria. An example includes
peeling potatoes, which will result also in sneezing or wheezing.
Some plants can also sensitize the skin to UV irradiation. For example,
plants from the carrot and citrus families. The fuocoumarins in these
plants penetrate moist skin and will burn the skin upon exposure to sunlight
or fluorescent light.
Plants can also cause simple primary chemical irritation similar to skin
damage produced by acids. Plant examples here are buttercups, daphne, and
peppers. I'm guessing that this is the basis of pepper sprays causing of
eye irritation.
My guess is that you are experiencing a contact allergic reaction similar to
poison ivy. It would be interesting if someone could collect enough
Drosera dew to use a microprobe to measure the pH.
Regardless, all of this can be easily solved: wear gloves and long sleeved
shirts when working closely with your drosera or pinguicula or grin and bear
it.
David Mellard, PhD
Toxicologist
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