To industry folks, it's the latest scare-of-the-month. To health care and environmental advocates, the issue is first, do no harm. The subject being debated is the simple, other life-saving medical device - the plastic intravenous (IV) bag.
The bag is made of polyvinyl chloride, a hard plastic. When mixed with the plasticizer di (2- ethylhexyl) phthalate (DEHP), PVC becomes flexible and suitable for medical tubing and IV bags. More than 80% of the IV bags used in the U.S. are PVC plastic manufactured mainly by Baxter Healthcare Corp., Deerfield, Ill., and Abbott Laboratories, North Chicago, Ill.
DEHP is associated with PVC not through chemical bonding but via weak van der Waals forces, so small quantities eventually migrate into any substance- including saline- contained in the bag. In a 1995 study, Baxter Healthcare found that DEHP can reach concentrations of 5 ppm in intravenous fluids. This amount, says Joseph DiGangi, a scientist in Greenpeace's Toxic Campaign, Chicago, and a member of the 170-member coalition Health Care Without Harm, Falls Church, VA., is more than 800 times higher than the amount of DEHP the Environmental Protection Agency permits in drinking water.
EPA's standard is set at 6 ppb, but its stated goal is a zero concentration for DEHP in drinking water. "If EPA thinks the goal for DEHP should be zero, why should DEHP be in a medical product containing a fluid that will be infused into patients?" DiGangi asks.
Leaching is especially troublesome if the substance has fat components. Makers of the anticancer drugs Taxol and Taxotere, for example, warn against PVC-DEHP equipment to administer the drug intravenously.
Animals fed high doses of DEHP have exhibited various problems, including damage to the liver, kidney, heart, and testes. Damage varies with the species studied, and the studies have been faulted for a variety of reasons. In fact, the Food and Drug Administration is reviewing the studies. Still, in 1986, EPA listed DEHP as a "probable human carcinogen." Premature infants and chronically ill adults are at special risk for exposure to DEHP.
Studies have never shown direct harm to humans from the leaching of DEHP from PVC medical devices. Fred Krause, director of the Chlor-Vinyl Campaign for the Chlorine Chemistry Council for the Vinyl Institute, says: "The use of PVC in this [medical] market has been well established. It has been used safely for over 40 years without any ill effects as far as we can tell."
Baxter spokeswoman Deborah Spak adds, "The large
body of scientific studies done over the past several
decades shows that the amount of DEHP leaching out is
safe." She also notes, "In general, PVC bags
offer many exceptional performance characteristics that
other materials don't offer." PVC bags can
be centrifuged, they are flexible, they offer optimal
clarity, and they can be sterilized at very high
temperatures.
The health care coalition counters that DEHP's potential health effect - such as liver cancer and impaired sperm counts- would only become apparent years after exposure, making it difficult to link the damage to DEHP. Furthermore, the coalition argues, no long term, comprehensive epidemiological studies have been done to ferret out the health effects of DEHP exposures in humans.
The issue becomes more tangled: Phthalates are toxic, but they can also be beneficial. Several years ago, DEHP was found to leach into blood stored in PVC bags. The amount leached depended on the amount added to the PVC in manufacturing. The leached DEHP osmotically stabilized red blood cell membranes and thus substantially increased the shelf-life of blood.
The vinyl chloride industry and IV bag makers like to tout DEHP's beneficial effects on red blood cells. But coalition members, Di Gangi, and Ted Schettler, science director for the Science and Environmental Health Network, Boston, argue that other, nontoxic stabilizers can be found. Moreover, unlike the haphazard concentrations of DEHP found in blood under storage conditions, the nontoxic substances could be deliberately added to blood in precisely known concentrations.
Alternatives to PVC-polyolefin bags for example--are available and are claimed by health care advocates to be cost-effective. Some IV bag manufacturers, however, claim that polyolefin bags are not as clear or as pliable as PVC bags, and they melt at the temperature needed to sterilize IV fluids. They contend that radiation sterilization would hike manufacturing costs.
But the coalition points out that B.Braun/McGaw of Bethlehem. Pa with roughly 18% of the market in the US., makes only polyolefin bags. The company says its bags withstand the high temperatures needed for sterilization and are comparable in cost to PVC bags. Jackie Hunt Christensen, a co-coordinator of the coalition, says the average cost of vinyl and olefin bags ranges from 85 cents to $1.00 per bag, but hospitals usually contract with manufacturers for several years and can frequently negotiate a lower cost.
Non-PVC IV bags and tubing are widely available in Europe. Baxter Healthcare has FDA approval to market non-PVC bags for blood components in the U.S. and has purchased a Swiss company that sells non-PVC medical devices outside the U.S. A spokeswoman for Abbott Labs says the company "is developing alternatives to PVC."
PVC medical products comprise only 6%of the total North American vinyl chloride market, Krause says. Most PVC goes into the making of construction materials. A switch to PVC alternatives in medical products wouldn't be welcomed by the industry, but it wouldn't devastate it either.
Balancing the slight harm to the vinyl chloride industry and the availability of cost-effective alternatives against studies--albeit ambiguous--that show potentially harmful health effects to humans dictates a prudent switch to non-PVC, DEHP free alternatives.
|
If you have come to this page from an outside location click here to get back to mindfully.org |