PHILADELPHIA - Rationing medical care is denounced as immoral in the United States, yet it goes on daily in hospitals, clinics, nursing homes, ambulances and pharmacies.

Since 2006, this country has had worsening shortages of sterile generic injectables - drugs given by shots or intravenously. Currently, more than 300 medicines crucial to treating cancer, infections, cardiac arrest, premature infants, pain and more are in short supply.

The reasons for this predicament are complex, and the fixes elusive. The scope, however, is clear from surveys of medical and trade groups. The latest, a University of Pennsylvania poll of oncologists released last month, found 83 percent had dealt with shortages by delaying cancer treatments, omitting doses, using second-choice drugs or sending patients elsewhere.

"Oncologists are facing wrenching decisions about how to allocate lifesaving drugs," said cancer specialist Keerthi Gogineni, who led the Penn survey.

Why aren't patients and families up in arms?

They may not realize their care was compromised or complicated by a shortage unless their caregivers are unusually candid.

"Patients in an intensive-care unit often don't know they've been impacted," said pharmacist Erin Fox, who tracks shortages as manager of the University of Utah's drug-information service. "And the hospitals don't want folks to talk about it. They don't want to admit, 'We had a patient who died because we didn't have this drug.' "

The secret human toll is rising. In the last three years, dozens of deaths due to contaminated drugs have been linked to producers and vendors who have capitalized on shortages. The Institute for Safe Medication Practices (ISMP) in Horsham, north of Philadelphia, received hundreds of reports of medication errors and near-disasters, and 15 deaths related to shortages when it surveyed 1,800 health-care practitioners in 2010.

"This is the worst I've ever seen in over 40 years as a pharmacist," said Michael Cohen, ISMP president, who contributes to The Inquirer's Checkup blog. "It's truly a public health crisis."

One group of patients has been acutely aware and outspoken about the crisis because it threatens their health every day.

These 30,000 Americans cannot eat by mouth, usually from digestive diseases. They must get all nourishment - from vitamins to fat - in a customized, sterile solution pumped into a heart vein, called total parenteral nutrition, or TPN.

"We were very vocal in outlining for (government officials) what we think needs to be done," said Joan Bishop, director of the nonprofit Oley Foundation in Albany, N.Y., a TPN support network. "You can't just let people starve."

Among the group's stalwart activists is Bettemarie Bond, 42, of Levittown. She suffers from rare digestive and metabolic disorders and has been on TPN since 1990. A single bite of, say, pizza, would set off excruciating inflammation in her pancreas and gut.

When she was in her teens, doctors told Bond to prepare to be an invalid. Instead, helped by her parents and TPN specialists, she graduated from college, bought a house and became a pediatric occupational therapist. She works with autistic preschoolers and hides her infusion pumps in a snazzy backpack.

To do all this, Bond has to conserve energy; even taking a shower can exhaust her. The shortages add needless stress. Consider that severe selenium deficiency can cause heart damage, yet she has not had the trace element for almost a year. She has gone without IV multivitamins for months.

Though shortages occur in other developed countries, the U.S. is especially vulnerable, experts agree.

In a recent analysis, Food and Drug Administration officials cited a root problem: U.S. factories that make sterile injectables are few, aging and inadequate, and manufacturers have no economic incentives to upgrade. When equipment breaks or inspectors find problems, it's often easier to quit making the injectables - which have high production costs and low profit margins.

Only seven companies now make virtually all sterile injectables in the U.S., their plants running round the clock.

Experts cite other factors behind shortages, including hospital group purchasing contracts that drive down prices, hoarding and low insurance reimbursements.