WASHINGTON — A new vinyl industry study says PVC manufacturing produces at most 1 percent of the toxin dioxin released into the environment, countering claims that PVC production accounts for significant dioxin releases.
The Vinyl Institute study comes as the Environmental Protection Agency is completing an inventory of dioxin in the United States, part of a long-term reassessment of dioxin's health and exposure effects.
The VI study, delivered to EPA Aug. 10, found that PVC manufacturing most likely produces about 24.3 grams of dioxin a year, with that amount falling to 16 grams if waste that is landfilled is not counted. About 3,000 grams of dioxin are produced in the United States each year.
That compares with a 1993 Greenpeace estimate of between 283 grams and 565 grams of dioxin a year from vinyl production.
The study means that vinyl manufacturing should not be a high priority in EPA's attempts to reduce dioxin emissions, said William Carroll, vice president of chlorovinyl issues for Occidental Chemical Corp. in Dallas and a spokesman on the issue for Morristown, N.J.-based VI.
``If we had been a 500-gram source, I don't think EPA could ignore it,'' he said.
Vinyl industry emissions include 12 grams from on-site hazardous waste incinerators, but those will be cut to 1-2 grams a year within five years under rules EPA is developing, Carroll said.
An April EPA report said the agency could not make definitive release estimates for the industry, but said the Vinyl Institute study and previous information would allow it to make reasonable estimates.
An EPA scientist involved in the dioxin measuring project, David Cleverly, said the agency still is evaluating the study but said the vinyl industry used EPA methods for measuring waste-water and stack gas releases.
EPA policy officials were not available for comment, but Cleverly said the low emissions still could be a problem, if a particular plant's dioxin emissions result in significant human exposure in a local area.
Greenpeace scientist Pat Costner said she had not seen the VI study, and said the environmental group has not updated its own studies. Other recent studies point to PVC manufacturing being a significant source of dioxin in a river in Germany, she said.
Dioxin can be dangerous in very minute quantities, and has been linked to cancer, reproductive and developmental problems, endocrine effects and immune-system problems, health officials said.
The VI study does not include dioxin releases from one of the EPA's top producers of dioxin, medical-waste incinerators. Some health-care groups say incineration of PVC medical products produces significant amounts of dioxin.
The EPA's dioxin inventory released in April listed medical-waste incinerators as the third-largest producers of dioxin, generating about 480 grams a year.
Charlotte Brody, co-coordinator of Health Care Without Harm in Falls Church, Va., said it is not clear how much dioxin in medical waste comes from PVC. But since burning chlorine produces dioxin, and PVC is 57 percent chlorine, hospitals need to eliminate the burning of PVC, she said.
Carroll said that about 75 percent of the chlorine in a medical-waste incinerator is from PVC, but he said studies have shown that incinerator operation is the key to dioxin production, not the type of material burned.
There are plenty of other sources of chlorine in medical incinerators, including blood and saline, he said.
Removing the PVC from incinerators still would leave enough chlorine to cause problems, if the incinerator is not operated properly, he said.