I CAN NEVER resist the Red Cross. All my self-conscious penny-ante marks of good conduct (saying "please," recycling, moderate-to-generous tipping) won't do a burn victim as much good as a pint of O-negative.

So when the blood van pulls up across the street from my office every month, I go and I sit and I fill out the form. I have to answer the list of yes/no questions every time, and they take on a ritual significance, like the Four Questions of Passover.

Some excerpts: Am I over 110 pounds? Yes, and thank goodness. Proof for my mother that I really eat three meals a day. Was I born in certain countries in western Africa, or have I received a blood transfusion there since 1977? The questionnaire asks these and other questions relating to Africa because of a rare strain of HIV that's popped up there. I check "no." Sub-saharan Africa has 12 million AIDS orphans, and I get to fiddle with checking off boxes in a clean room. Lucky isn't strong enough a word.

Another risk: mad cow disease. Well, I'm a vegetarian, which helps avoid old Creutzfeldt-Jakob disease. But they don't ask about what I eat, just about visits to England and long stays in other bits of Europe. Despite my envy of rich expatriates in Paris, I at least get to check that "no" box. Take that!

In general, you must wait 12 months after getting a tattoo to donate. Again, square Sumana gets to blow a raspberry at the edgy hipsters.

And then the few uncomfortable questions start. Not because I have to weasel around the answers (I don't), but because these are the ones that the doctor also asks me, face-to-face, in a carefully nonjudgmental voice. "Have you ever used needles to inject yourself with drugs, steroids, or anything else not prescribed to you by a doctor?" "Have you taken drugs or money as payment for sex, even once, since 1977?" "Are you donating today just to get tested for HIV?" I answer them all "no."

I have to remind myself that they ask everyone these questions, that the doctor has not decided that I look like "that sort of girl." I don't have to remind myself that I live a pretty risk-averse lifestyle regarding blood-borne infections, especially HIV. The questions have reminded me of this.

Returning to work after the most recent donation attempt, I expressed relief that I'd "made the right choices in life" and avoided several high-risk categories. One colleague gently criticized me for implying a criticism of her acquaintances who choose to exchange sex for money. Well, for most of the women in that profession, it wasn't a choice and they'd rather be out of it, and thank God I was never forced into it in the first place.

But the second retort I heard stung a little harder. A gay colleague reminded me of one of the deal-breaker questions: "Are you a male who has had sexual contact with another male, even once, since 1977?" As far as I can tell, gay men don't choose to be gay. But the relevant medical experts agree on classifying gay sex in the "high-risk" category for HIV exposure. Yes, the ban feels unfair for the safer-sex protocol-following monogamous gay male couples, just as it would feel unfair for vegetarian me to live five years in England, come home, and get barred from donating on account of mad cow disease. But barring high-risk populations from donating to the blood supply, in combination with lab tests that screen donated blood, have lowered the chance of receiving an HIV positive blood transfusion to one in 1.5 million.

I've reconciled myself to the tradeoff but can understand gay men's unhappiness with the ban. As it happened, my personal choices in the form of an unbalanced diet kept me from donating anyway. The doctor performed a pinprick test on my finger and checked the iron levels in my blood (iron helps make red blood cells). I came up just under the mark. Time to break out the prune juice and kale, for my sake as well as someone else's.

It was a good reminder that all of our personal choices have consequences. Ethical consumers know this. But we can also affect the world as producers. And even if you're poor, as long as you're basically healthy, you can produce something really irreplaceable and give it to someone who needs it.

The summer dip in donations is hitting blood banks hard, and they're below emergency levels, so go to BeADonor.com and find the hours of your local blood drive.

Sumana Harihareswara's MC Masala appears each Thursday. You can e-mail her at sumana@crummy.com.