In nearly every country in the world, there is a shortage of kidneys for transplantation. In the United States, around 73,000 people are on waiting lists to receive a kidney. Yet 4,000 die every year before the lifesaving organ is available.

Worldwide, about 66,000 kidney transplants are performed annually. By far, that’s too slow a rate to help an estimated 1 million people who have end-stage renal disease.

Is a global market for organ sales the answer? Can a for-profit system exist, save lives, and still not exploit the poor? A series of experts — medical doctors, international health experts, and ethicists — looked at the issue on Feb. 8, in the second of four Harvard conferences this academic year on current controversies in global health.

“It’s an extremely sensitive and troubling topic,” said symposium Chairman Daniel E. Wikler, the Mary B. Saltonstall Professor of Population Ethics, who is on the steering committee of Harvard’s Program in Ethics and Health, a conference co-sponsor. (The other was the Harvard School of Public Health.) “We have here the elements of tragedy.”

On one side, he said, are patients for whom “life hangs in the balance.” On the other, there are the desperately poor whose organs now have monetary value, and who are vulnerable to exploitation in a growing industry known as “transplant tourism.”

Kidney transplantation was the focus of the three-hour conference. In the case of kidneys, said Wikler, even the poorest person in the Philippines or India has “a couple of gemstones — diamonds — on each hip.”

Even in the face of desperate illness, there are moral standards to protect, said the one-time chief ethicist for the World Health Organization (WHO). But “with life hanging in the balance,” said Wikler of organ markets, “we need very convincing moral reasons to get in the way.”

Medical systems across the world are far from meeting the needs of kidney-transplant candidates, said Luc Noël, who tracks transplantation issues for WHO in Geneva. But there is also an urgent need for global resolve, he said. In the past decade, WHO and other groups have called for international standards that will protect the poor, monitor transplantation quality, keep the process transparent, and ban commercialization (now driven largely by the Internet).

In the present global hodgepodge of transplant tourism, thousands of patients — from the United States, Israel, Saudi Arabia, and other prosperous nations — get the kidneys they need, he said. But their donors (some of them exploited by organized crime) frequently get the short and sharp end of the stick.

Noël cited one survey of kidney donors in Pakistan’s for-profit market, where two-thirds of the operations are performed on foreigners. The survey showed that almost 70 percent of donors were slaves or bonded laborers; 90 percent were illiterate; 88 percent had no improvement in economic status from the donation; and 98 percent reported a subsequent decline in health, including chronic pain from large incisions.

WHO and its decision-making body, the World Health Assembly, have taken stands against commercialized kidney transplantation. Their goal is to establish within a decade a binding international document that protects the poor.

Prevention is one way of reducing the need for kidney transplants, acknowledged Noël. But in the meantime, waiting lists could shorten through more cadaver donations and more by living donors (a step he called “a civic gesture”).

In the United States alone, said Noël, one additional donated kidney a month to each of 58 donation service areas would create equilibrium — an equal number of waiting patients and available organs — by 2013.

Meanwhile, there have been country-by-country improvements, he said. Egypt is debating tighter laws; so is Pakistan. China recently cracked down on medical tourism, reducing the number of operations by one-third between 2006 and 2007. (Practices in China also add another layer of moral complexity: All 8,000 kidneys transplanted there in 2006 came from executed prisoners.)

In the Philippines, kidney transplants are officially restricted, with only 10 percent of operations supposed to go to foreigners. But the reality is different. One slum of Manila is known as “Kidneyville” for the high number (3,000) of organ donors living there.

Worse, Philippine health officials last December wrote a health policy that would make organ sales open and legal. That would mean sick patients would “descend on Manila [like] predators,” said Harvard Medical School (HMS) professor of surgery Francis L. Delmonico. A transplant surgeon, he’s medical director of the New England Organ Bank in Newton, Mass., and travels worldwide as a member of the ethics committee of The Transplantation Society, a scientific group.

Even in a regulated, government-run version of transplant tourism, “unethical realities” lead to exploitation of the poor and the vulnerable, said Delmonico. Waiting lists of sick patients are a concern, he acknowledged — but studies suggest that a profit-based international transplantation market “will destroy altruism” and reduce the number of kidney donations from both live donors and from cadavers.

To put waiting lists in perspective, he added, half of all patients on the lists are “medically ineligible” for transplants anyway — too sick for the required surgery.

A market-based system for kidneys is “workable and defensible,” argued conference presenter Julio J. Elias, an economist at the State University of New York, Buffalo.

Elias is co-author of a widely circulated paper that shows — with a flurry of economics formulas and cost-benefit analyses — that market incentives would increase the supply of organs available for transplanting, and would shorten waiting lists.

Still, he added, “The market may work, but some people may feel it’s repugnant.” And the effect of this repugnance on markets was the focus of his talk.

This culturally shared form of extreme dislike can sometimes mean certain transactions become illegal, said Elias. Horsemeat is widely illegal to sell, for instance, though it shares the same nutritional properties as the flesh of cows. Liquor used to be illegal, and so was life insurance. “Repugnance,” he said, “is associated with social costs.”

But the good news, in economic terms, is that perceptions of repugnance can shift along with other cultural norms, said Elias. If the price of beef goes up, he speculated, maybe the shared disgust at eating horsemeat will disappear — as the disgust at drinking did very soon after Prohibition.

Attitudes will change regarding legal transplantation markets for kidneys, he predicted, “when it is shown how efficiently prices will solve this problem.”

Two philosophers presenting at the conference disagreed. Nir Eyal, an instructor in social medicine in HMS’s Division of Ethics, argued that “dignitary harm” (an insult and/or injury to the dignity of a person) results from exploiting the economically vulnerable — a harm that unfairly spreads out and compromises every member of the same group.

Philosopher Samuel Kerstein, post-doctoral fellow in Harvard’s Program in Ethics and Health, was wary of markets for organs because of Immanuel Kant’s “Formula of Humanity” — in summary, “Act always in a way that expresses respect for the value of humanity.”

“To have value as a person is to have incomparable worth,” said Kerstein – so a market for organs that treats the poor as “tools available for the right price” is wrong. Organ transplantation was something Kant had a direct opinion of, though he died in 1804. In 18th-century Europe, the poor were being exploited for their teeth, which were transplanted into the jaws of the willing rich.

Today, said Kerstein, “selling organs is wrong in the current context it is likely to occur.” That is — with little respect for human dignity, particularly for the dignity of the poor.

But perhaps there are permissible alternatives to buying and selling organs, he said. Opt-out programs for organ donation, for instance, which have increased the number of cadaver donations in Spain, might be a possibility.

Or even an “organ draft,” suggested Kerstein, provocatively — a lotterylike system that would require a random set of the healthy to donate organs. “If we’re not willing to do that sort of thing,” he said, “we have to ask ourselves, ‘Why not?’”