Bloody hell - is that art?

I wonder how much menstrual blood will be flowing in this year's batch of degree shows. Art students, after all, are expected to break every kind of taboo. I can't tell you the number of times I've had to pronounce on the suitability of a pierced penis here, a scarred rape victim there, jostling for space with simulated (I hope) cocaine leaves and a row of ceramic vaginas that I had to persuade the vice-chancellor were actually ashtrays. But I can't remember any student artwork that has dealt graphically and explicitly with periods.

What prompted me to contemplate this strange omission was Tracey Emin's current show at the Hayward Gallery. I'd taken in the statement quilts and the neon slogans, the reconstructed beach hut, the confessional videos and photographs. But just as I was getting a bit weary of masturbation and miscarriages, I was stopped in my tracks by one item, tucked unobtrusively into a corner. There, arranged in pairs in glass cabinets, in varying degrees of dampness and redness, was a selection of used tampons. And, despite the reputation of this most personal and challenging of artists, they made quite an impact. Even Emin herself has confessed to feeling a bit iffy about including them.

Menstruation has never had a good press. Men recoil from the very idea of it, and religions claim it is proof of women's inferiority and filthiness. Fairy tales abound with the image of blood as a symbol of corrupt woman. Think of Cinderella's avaricious ugly sisters, their bleeding toe and heel a testimony to their monstrous woman-ness. Think of Snow White, untainted until she eats the red side of the apple, or the pure white Sleeping Beauty, who falls from grace through the prick of a finger and a spurt of blood. Women are told to keep away during their periods, or the bread won't rise, the corn will wither, the milk will curdle.

And attitudes haven't changed all that much even now. Menstruation is still regarded as either embarrassing or as disgusting. We talk about having the curse, or having the painters in, or being on the rag. Until relatively recently, the whole idea of periods was so distressing that commercials for sanitary towels were banned from television. Even when they began to appear on our screens, blue ink had to be used to demonstrate their effectiveness. Red for blood was considered beyond the pale.

It was Germaine Greer who, in The Female Eunuch, first urged us to stop colluding with the oppression and to come clean. Don't hide your tampon away when you have to go to the loo, she exhorted us. Brandish it with pride. Learn to celebrate yourself, get drunk with your womanhood, try tasting your own menstrual blood. "If it makes you sick, you've got a long way to go baby."

Since then, several feminist artists have also incorporated menstruation in their work. In The Red Flag, Judy Chicago depicts a dripping tampon being removed. Rozita Fogelman splattered a canvas with a representation of menstrual blood. Ipshita Thakur painted packages of Whisper sanitary pads suspended in space. Usually these pieces have been designed to make a political message. But such direct statements are somewhat alien to Emin, whose elliptical, intimate style seems closer to that of feminist poetry.

In the poem The Watch, Marge Piercy refers to menstruation as the "red splash of freedom" for so many anxious women, while for others it's a signal of infertility: "Another month, another chance missed./Forty years of our lives, that flag/is shown or not and our immediate/and sometimes final fate determined."

It's a sentiment echoed by Emin in the scrawled statement accompanying the exhibit. "Some days I don't bleed at all - and one day I won't. There'll be no blood and my womb will be a dry, redundant bag," she writes. "All that 23 years of bleeding has helped me be who I am."

Her vulnerability is made even more poignant in the context of the rest of the exhibition: the raw filmic description of a botched abortion; the sad scattering of baby clothes, the half-finished crocheted shawl, the plastic pregnancy test tube placed alongside the tampons. She didn't want children - "if I'd had them I would have hung myself by now" - but her plaintive mixture of sadness and defiance, certainty and guilt, must resonate with anyone who has had to wrestle with similar heart-wrenching choices.

At the end of her written piece, Emin strives to explain how she has turned her own waste into art. "And now - I can look at these sodden little tampons - and I can think - I made them - I made that blood - and the inside of my body cast those shapes." This attempt at fusion between a woman's body and her art is similarly evoked by Erica Jong in her poem, Inventing My Life, where she compares writing to bleeding: parchment becomes "a tampon to the muse's womb".

I doubt that Emin, who consistently resists being classified, would much like to be described as a feminist, but this item proves that she is. For these sad, bedraggled bits of detritus typify her quest to distil her own experiences as a woman into statements both touching and profound.

Emin has now granted permission for the next generation of women artists to cast off their shame, and to flaunt their freedom in vermilion and scarlet, poppy, cherry, pillar-box red. Maybe it's happening already. Maybe next week I'll have a lot more explaining to do when the vice-chancellor comes to visit.