Katherine D: First, I have to say that I love reading your comments! I'm
responding to your message re. UV radiation. I only have a moment to "talk,"
since I'm on a tight deadline at work (writing a science update on global
warming, aargh!). But since ozone depletion is one of my "specialities," I'd
like to add a quick point ... or two....

These days, when you're talking about UV radiation, you need to remember
that stratospheric ozone depletion has greatly increased the amount of UV
to which we in the mid- and north-latitudes are exposed. This
depletion gets worse the farther "poleward" you go.

The ozone layer is most depleted in the spring, across the planet. In
the poles, the springtime depletion is about 50%, but it's still about 10-15%
in southern Canada, the northern States and Europe. In other words, the
earth's natural sunscreen isn't working nearly as well as before.

It's true that you'll get more UV closer to the equator. But the
depletion is so great now in Canada, for example, that it's (roughly) as if
we've moved to Florida! The Canadian Dermatological Association estimates
that one in seven children born this year will develop skin cancer in their
lifetime (benign and malignant).

I don't think -- based on the reports I've read on skin cancers, increased
incidence of cataracts and immunological damage done by UV -- that dark
skins protect a great deal more than lighter skins. Skin cancers are
increasing at an alarming rate, in people of all skin colours (but it's true
that fair-haired people are more at risk).

Also, *both* the sunlight intensity and the total amount of hours you're
outoors (even walking to lunch, at work, for example) make a difference in
your total amount of UV radiation exposure. It all adds up, so it's important
not to overlook the many "less noticeable" times we're outdoors -- as well as
being careful on big southern vacations, or a day at the beach.

A plug for the ozone layer and future human existence: the worst single
contributors to ozone depletion are vehicle air conditioners, whether or not
you turn them on -- because they tend to leak CFC. In Canada, you can get
your air conditioner drained of CFC -- the technician safely captures and
stores the CFC for later destruction. Also, when you get your fridges and
freezers serviced, make sure the technician doesn't release the CFC into the
air.

I know this isn't direct breastfeeding stuff, but I couldn't resist. --
Andrea C. -- science writer, BC
Environment