The word "bank" typically refers to financial institutions, large and small, from the storefront where you go to cash your checks to the big investment firms of Wall Street. Yet there is a class of banks that deals not with money but with bodily fluids—blood, sperm, and breast milk. These "banks" aren't part of our financial system, but banks they are, nevertheless.

To Kara W. Swanson, author of the new book Banking on the Body, that word is more than "mere metaphor"; it carries with it ideas and consequences for how we perceive the body and its byproducts. "This term, borrowed from financial banking and redolent with implications of markets and cash flows, created the context in which Americans learned to think about body products and in which we developed our contemporary laws governing property in the human body," she writes.

I spoke with Swanson, a professor of law at Northeastern University, to learn more about these banks and the market for our body products. A lightly edited transcript of our conversation follows.

Perhaps you can just start by sketching out a bit of the historical background. Where does the term "banks" first get used to talk about storage of the body's fluids and organs? How has that metaphor evolved over time?

This question was my starting question for the book. Like most of us, I was very familiar with the body "bank," especially the blood bank, but I had never stopped to think about why we called it a "bank"—and the more I thought about that, the odder it seemed to me. What sort of bank goes around begging for donations?

Finding out where that metaphor came from was the easy part. It originated in a very particular historical moment, 1937, in Depression-era Chicago. One doctor, Bernard Fantus, was charged with managing the supply of blood for Cook County Hospital, which was the public hospital in Chicago—it treated those who could not afford to go to public hospitals, and it relied on public funds. In 1937, money was very tight, and the hospital was operating on a shoestring budget.

Blood transfusions in the 1930s had become pretty common and safe (30 years earlier they were neither), but the problem was that they were expensive. Since doctors had begun working in earnest to incorporate them into medical care around the turn of the 20th century, they had relied on paid blood sellers as the most common source of supply. Sometimes they could access volunteers, usually friends or family of the patient who were there at the hospital, but that didn't always work.

Blood transfusion requires matching blood types, and there wasn't always a ready volunteer who had the right blood type. It also took quite a while to test anyone to find out their blood type. By the 1930s, the solution had become "professional-donor" registries. These might be run by a hospital, or free-standing institutions, either for-profit or non-profit. They kept lists of willing blood sellers, who had been pre-screened by a physical exam (most importantly, to make sure they did not have syphilis or malaria, which could be transmitted by blood) and whose blood type had been determined. When a transfusion was needed, a doctor could call the registry, and they would send a "donor" of the correct type. That donor expected payment, and the patient got the bill—a blood transfusion involved a direct sale from a particular professional donor to the patient.

Fantus' patients did not have the money for that bill—usually $25 to $50 dollars. And they often did not have available volunteer donors either. At Cook County, as at other public hospitals around the country, patients were literally dying for lack of blood—deaths that doctors knew could be avoided if blood was available to transfuse them.

This is the context for the introduction of the bank metaphor as a means of understanding body product exchange. Fantus' innovation was to break the direct person-to-person means of getting blood and to reconceive blood for transfusion, that is, blood as a body product, into an abstract unit of credit. He set up a refrigerator full of units of blood.

This seems common sense and ordinary to us today, but it was a big conceptual shift. When a doctor needed blood, he requested a unit of typed blood from the refrigerator—which Fantus came to call his "bank." The innovation was that the doctor needed to replace that blood. But the replacement no longer needed to be immediate, but could be later in time. And the replacement need not match the type of the blood withdrawn. It just needed to be a usable unit of blood (about a pint) that would restock the inventory. Almost any patient, even the indigent, could provide a pint of their own blood once recovered, or find a friend or family member to provide one—when that replacement did not need to be provided at the time of urgent need or match the patient's blood type.

Fantus called his refrigerator a "bank" because he wanted the hospital's doctors to take their repayment obligation very seriously. He told them it "was not a mere metaphor." Just like a bank could only pay out money if it received money (a concept very familiar after all the bank failures of the early 1930s), his "bank" could only have blood available for their patients if they put equal amounts back. It needed to be "balanced."

Before modern genetics, blood was considered a bit like DNA is today—the carrier of individuality, that which links someone to their family.

The metaphor was thus a way of solving a medical problem—how to get this life-saving body product to all patients who needed it, not just those who could afford to buy it? His solution was successful at Cook County, and as soon as he publicized it, doctors all over the country, who hated the idea that patients were dying needlessly, rushed to adopt it. Large urban public hospitals opened "blood banks" in the late 1930s and early 1940s, and after the idea of blood donation became much more publicly understood during the WWII national blood program, blood banks became the ubiquitous feature of hospitals they are today during the late 1940s and 1950s.

That, as I said, was the easy part. What I aim to do in the book is to understand how the metaphor spread, which it did in two ways. As I just described, it became the way we understood the blood supply, which was a crucial feature of the rise of modern hospital-based medical care. Modern surgery depends on the blood bank. But the metaphor proved so powerful as a way of thinking about how a body product is exchanged between strangers that it colonized other body products. Both those that predated the blood bank, that is, breast milk, which was exchanged through mothers' milk stations beginning in the 1910s, and those that came into medical use later, such as sperm, beginning in the 1950s.

In your book, you argue that, like Fantus said, the "bank" terminology has never been "mere metaphor." Can you talk about the ways that the bank metaphor has shaped our understanding of these systems? How has the connection between medical banks and financial institutions manifested?

The metaphor was very useful in solving Fantus' problem—improving access to a body product supply. But it relied, as he well knew, on an analogy to financial banks, and implied that body products should be treated like money in the bank.

Financial banks are a bedrock of capitalism and facilitate markets. The analogy between bodies and markets didn't particularly bother Fantus—he, like other doctors, was very comfortable with buying blood and milk from suppliers. But it did bother some people who preferred to think about the human body as something which should be kept out of markets, that buying and selling body bits was immoral, or at least dangerous to the selfhood of the supplier, and perhaps even the recipient.

The banking metaphor, by treating body products as abstract units, that could be accounted for in balance sheets, also contradicted our understanding of bodies as unique. Before modern genetics, blood was considered a bit like DNA is today—the carrier of individuality, that which links someone to their family. To share blood was to share common traits. Treating each unit of blood as the same contradicted that common understanding.

Blood bank official Phil J. Swigart holds two bottles of blood identified as "white" while another bottle labeled "colored" sits at right in Little Rock, Arkansas, on April 8, 1959. Racial segregation of blood was mandated by Arkansas law. (AP)

What happened as the metaphor became more used in the 1950s and 1960s, was that a backlash developed against the market implications of the metaphor. The doctors and lay people who ran blood banks in the 1950s and 1960s, pushed the metaphor to its extremes—they told patients that each transfusion was a "loan" that needed to be repaid. Patients could repay in kind, or pay stiff replacements fees instead—fees that a bank could use to buy blood from a professional donor—always with the goal of keeping sufficient inventory.

The emphasis on buying and selling led blood banks into trouble in the courts—attorneys for patients injured from transfusions (which happened sometimes, if mismatched blood was given, or the blood contained a disease) argued that banked blood was a product. Product liability law was developing to find the manufacturer of a dangerous product liable even without negligence. Doctors, blood banks, and hospitals were horrified to have themselves considered product manufacturers. They began to backpedal from the banking metaphor by trying to make banked blood seem less like a product exchanged in markets.

What happened, with blood banks, and also with other kinds of banks, is that the banking metaphor and the backlash encouraged doctors, patients, and those of us who might be suppliers, to focus on one aspect—the supplier. Was the supplying body paid or unpaid? Paid suppliers, who were obviously entering into a market transaction, were treating their bodies as a source of private property, and were acting as though they were selling a product. Unpaid suppliers, were seen as giving gifts, out of altruism, and keeping themselves out of a market.

This narrowing of focus left out two aspects of body-product exchange that Fantus had been concerned about when he developed the metaphor, and which his predecessor doctors had focused on in the beginning of using body products as therapeutics: creating an adequate supply, available when needed and making sure that all patients could access that supply. I argue in the book that the metaphor and its backlash created a narrowing that has led both to contemporary laws that regulate body products mostly from the aspect of supplier payment, and a situation in which those other aspects are often not well met—a safe and adequate supply and availability based need. This, in turn, has led to current injustices in the use of body products as therapeutics, not just those which are banked, but unbankable ones, such as organs.

What I learned as I investigated the body banks was that the metaphor had an unfortunate and unintended effect on body-product exchange. By understanding its history, and remembering the body product exchange before the body bank, we can begin to address current injustices.

Can you say more about those injustices? How do they play out? How does "banking" play a role in perpetuating or even instigating them?

Take perhaps the most common nonbankable body product today—kidneys. It is no secret that every year, more Americans go on lists as waiting for a transplant than donated organs become available. The disparity between supply and demand keeps growing. In these conditions of scarcity, not all who need this body product can get it. Those with resources, can, if they choose, leave the U.S. and travel elsewhere to purchase an organ through international grey markets. On average, those with more socioeconomic resources tend to receive kidneys, and those with fewer resources tend to supply organs. Because in the United States race tends to follow class, this tendency means that there are also racial disparities; a disproportionate number of racial minorities are suppliers, while African Americans tend to receive kidneys proportionally less often than European Americans.

I like to remind people that lots of altruistic gestures are compensated—the doctors, and nurses, and everyone who works on a transplant operation are all in caring professions.

This disparity is unjust. Many people have suggested that providing some sort of compensation to families who supply kidneys from a deceased loved one, or even those who act as living kidney donors, might decrease the scarcity, and thus this injustice. Such compensation is outlawed by the National Organ Transplant Act, passed in 1984. As I explain in the book, although early body products were always purchased by doctors, by the time organ transplantation became reasonably successful, the banking metaphor, and the backlash against markets in body products which it helped to create, supported swift passage of this law.

In law, we thus divide body products into two categories: those which we legally mandate as gifts only—all organs—and everything else, which can be gifted or sold, at the discretion of the supplier. Organs is defined broadly—bone marrow, for example, is an "organ." This means that bone marrow, which can now be extracted from the blood in a procedure similar to the way blood plasma is harvested, cannot be sold by anyone. (Blood plasma is routinely sold, by the way.)

A nonprofit organization in California wanted to experiment and provided $3,000 to bone marrow donors. Not a free market, not auctions on ebay, but a set fee, that would not be provided as cash, but in the form of scholarships, charitable donations, or housing subsidies. Their goal was to recruit more non-European American donors, because it is currently much harder for non-European Americans needing a bone marrow transplant to find a match. This proposal was against the law, and the organization needed to sue to use this approach.

I argue in the book that the simple pay-suppliers/don't-pay-suppliers approach to thinking about body products, which resulted from the banking metaphor, needs to be replaced with more nuanced thinking. Should we treat different types of organs (hearts v. bone marrow) differently? Can we think about compensation schemes that are not free markets, but are managed to support the public goals of increasing body-product supply? Can those schemes protect suppliers and recipients alike by keeping suppliers safe from exploitation, and recipients safe from diseased products? I use history to suggest that the answers can sometimes be yes. Body products used to be routinely paid for, and doctors thought about these potential problems and addressed them. Over time, we have forgotten this past, and come to assume that buying body products is always dangerous and bad.

I like to remind people that lots of altruistic gestures are compensated—the doctors, and nurses, and everyone who works on a transplant operation are all in caring professions. They are doing those jobs because they want to help people (at least we hope and assume so). But we wouldn't suggest that they shouldn't be paid because to offer payment for such efforts would be insulting or immoral or cause their altruistic tendencies to be replaced by mercenary concerns.

Yet that is how we treat organ supply—that offering money would do all those bad things. Why should the supplier of a body product be the only person in that life-saving supply chain who is not compensated? People might choose not to be compensated, but if they want to be, and if more folks will act as suppliers with that incentive, why not?

To give a more specific historical example, let's think about mothers' milk stations in the 1930s. At that time, in most cities, such a station existed. It was established and supervised by a doctor or doctors, and its daily operations were run by nurses. Lactating women came to the station to express their breast milk and were paid by the ounce. Payment was used to ensure an adequate supply. The supply was used for sick and/or premature infants who lack a maternal source of milk.

Doctors were trying to save lives. They created a controlled market—milk was bought by the ounce, processed, pasteurized and made ready for use for another baby, and then sold by the ounce.  The doctors controlled the sales. Milk was only sold based on a doctor's prescription, and the price varied—the well-to-do paid top dollar, the poor paid little or none. The station manipulated pricing to get the milk to as many babies who needed it as possible, and with the goal of bringing in enough cash to keep the station running, without trying to make a profit.  

That served two goals—a safe and adequate supply and maximizing recipients based on need rather than on wealth. But the doctors did not stop there.  They also thought about the mothers who sold milk as people whose health they could influence. These women, of course, had recently given birth, and had a baby, as well as perhaps other children. The stations tried to set the purchase price for their milk at a rate that would help these mothers stay at home to care for their own infants, rather than being forced to go out to wage work, endangering their babies' health by early weaning. The women also got free medical care in the form of check-ups, and free well baby visits, as they were required to bring in their own babies for weighing. They were also given nutritional and child care advice. All valuable forms of compensation in the Depression, when virtually no one had health insurance.

Doctors saw the market in milk as a win-win, benefiting their infant patients, but also the selling mothers and their children. Women reportedly earned enough money to buy cribs and baby clothes. One Detroit woman saved her earnings over three pregnancies and lactation periods and bought a small house. One New York woman, a Russian immigrant, saved her money to help pay her sister's passage.

Yet today, mother's milk banks describe themselves as donor banks, and state that buying milk would be harmful to suppliers and recipients alike. I have no problem with women donating excess breastmilk to the nonprofit milk banks, motivated by the desire to help other babies, but I find it a bit offensive that a for-profit company, Prolacta Bioscience, which sells a patented formula based on human milk, also fails to offer its suppliers any money, telling them their only reward is helping babies. Our acquired distaste for paid suppliers is supporting the business model of this company.

What is on the horizon for the body's natural resources? How are medical advances changing what body parts are commodities? What questions and challenges will these advances bring over the next few decades?

Property in the human body is becoming increasingly significant. Thanks to the biotechnology revolution, property sourced from the human body today includes not only body fluids and body parts, but also property derived from material aspects of the body, such as genes and cell lines. Some of this physical property is turned into intellectual property through the patent system. The Supreme Court in 2013 issued an opinion about the patentability of human genes in a case involving the BRCA1/BRCA 2 genes that can show increased susceptibility for breast cancer. There were a lot of strong feelings about what it means to own genes, and who should own them.

What I've learned from my historical investigations is that property sourced from the human body—even when we try to treat it, as one blood bank in the 1940s said "just like carrots and silver teaspoons"—never is just the same. We think and feel about it differently, and the law, even patent law, needs to acknowledge those feelings, grounded in our knowledge of ourselves and our bodies.

At the same time, as we develop biobanks as resources for genomic medicine, and become increasing able to transplant body parts—I am fascinated at the way human faces are becoming body products—the need to break out of the gift/sale dichotomy to think about body products more creatively and flexibly also is becoming more urgent. Regulation needn't be an on/off switch that bans all compensation out of worry about over-commodification.

We can think about, and regulate, new forms of body products individually, keeping in mind not just the presence or absence of supplier compensation, but the questions that drove the development of the first body products, and continue to drive the development of new ones: How can we have a safe and adequate supply? How can we maximize provision to patients based on need, rather than solely on ability to pay? And how we treat suppliers safely and respectfully? Answering these questions may involve markets and compensation, and it may also involve altruism and gifting, not as opposites, but as shared ways of supporting medical treatments that we all would like to have available for ourselves and those we love.