ROTTERDAM World markets match buyers and sellers for goods as different as oil and wheat or cars and computers. Why not for human organs like kidneys?
Strong demand for life-saving transplants and short supply of organs has raised ethical issues about whether humans should be treated like vessels to provide spare parts.
With a potentially vast supply of organs from often poor donors in developing countries for mostly rich recipients in the West, calls for "kidney for sale" schemes are getting louder.
The traditional ethical view that buying and selling organs is shameful -- upheld by legal bans on sales in Europe and North America -- is now under pressure due to a dramatic shortage of one of the most frequently transplanted organs, the kidney.
In the United States and Europe, most tissue for transplant is taken fresh from cadavers of the newly deceased. A smaller amount comes from live donors, mostly from a relative or friend.
"It is morally wrong to continue to let patients suffer and die on dialysis when we can do something to prevent it," Arthur Matas, a University of Minnesota transplant surgeon, told a conference in Rotterdam on European transplantation policy.
Those who defend these bans "are sentencing some of our transplantation candidates to death," he argued in a plea for a regulated market in organs to help meet the growing demand.
Matas was clearly in a minority amid speakers who warned a market system would discourage so-called "altruistic donations."
But defending the moral high ground is hard, because ever longer transplant waiting lists have fuelled a growing black market. The poor sell kidneys to the rich in what Netherlands Health Council adviser Michael Bos called "medical apartheid."
In a paper for the conference, Dr. Javaad Zargooshi called a commercial kidney system run in his native Iran since 1988 a failure. It had taken over 90 percent of the market, undermining voluntary donations, but donors had no post-operative care.
Gabriel Danovitch, a University of California at Los Angeles (UCLA) transplant surgeon, noted Hong Kong got half its kidneys for transplant from altruistic donors before it returned to Chinese rule in 1997.
"When Hong Kong could buy kidneys in China, live donations fell to 15 percent," he said. "In Israel, live donations fell by 30 percent when insurance companies said they would pay for 'transplant tourism' abroad.
In "transplant tourism," rich patients pay tens of thousands of dollars to receive kidneys in poor countries, where payments for donors ranges from around $500 in Iraq, $1,000 in India and $5,000 in Turkey, according to reports about the black market.
The problem is growing rapidly because medical progress has made kidney transplants safer just as rising levels of diabetes and hypertension are causing ever more kidney failures.
When the United States banned kidney sales in 1984, about 8,500 patients were on a transplant waiting list of about a year. Now they are estimated at 70,000 and the waiting time is five years or more, Mates said.
Waiting patients are hooked up several times a week to dialysis machines that purify the blood their failing kidneys can no longer clean. Their health deteriorates gradually, making a transplant a better and cheaper alternative.
Matas proposed a regulated system of kidney sales from live donors, with a state agency or private insurance company paying a fixed price to sellers. The state would ensure fair distribution of kidneys and long-term health cover for donors.
He rejected arguments this put a price on body parts, saying courts already pay damage claims for loss of limbs. "Prohibiting the poor from selling a kidney still leaves them poor and removes one possible option to improve their lives," he added.
China, long the most active kidney seller, has been accused for years of extracting organs from executed prisoners. Beijing has denied this and officially banned organ sales last year.
Swiss parliamentarian Ruth-Gaby Vermot-Mangold said nobody had a right to replacement organs: "If we in the rich West need organs, we will have to launch campaigns on our own ground to persuade people to act responsibly and donate their organs."
Our top photos from the past week.