Dioxin emissions from Spokane’s trash incinerator have exceeded permit limits for the first time, according to a report sent to air quality officials.
The new dioxin numbers are setting off alarm bells at City Hall because they are as much as 146 times higher than any previous amounts measured at the 8-year-old West Plains plant.
City officials are now second-guessing the accuracy of their own data.
Dioxin is a highly toxic chemical that can cause liver damage, immune system disorders and reproductive problems in minute amounts. It’s also been linked to some cancers.
Trash incinerators are one of the biggest sources of dioxin nationwide, according to the U.S. Environmental Protection Agency. The toxin is formed largely by burning the polyvinyl chloride found in plastic.
The amount of dioxin released from the smokestacks at Spokane’s incinerator has been very low, according to annual tests dating back to 1991.
That changed last year.
Two weeks ago, after the city’s solid waste department submitted its 1997 smokestack test report to the Spokane County Air Pollution Control Authority, the city asked for it back.
City staff and technicians from plant operator Wheelabrator Spokane Inc. have been reviewing the dioxin numbers for possible errors, said solid waste director Damon Taam.
Plant supervisors will meet with SCAPCA officials today at City Hall to discuss the problem.
“We’ve asked Damon Taam to submit additional information on why he thinks the numbers were so high,” said SCAPCA Director Eric Skelton.
“This is very uncharacteristic of the plant. It’s probably an anomaly,” Taam said Thursday.
Even if the numbers stand, the dioxin averages set by the state are only slightly above the permit limit of .50 nanograms (a billionth of a gram) per cubic meter, Taam said.
“People should not be concerned,” he said.
An environmental activist disagreed.
“The EPA recently found we can tolerate less dioxin than they originally thought. No amount is safe, and if we’re exceeding the standard, it’s probably a red flag,” said Bonnie Mager of the Washington Environmental Council.
If the plant is producing more dioxin than it did in the past, that’s a cause for concern, Skelton said.
The plant was burning Canadian oil field filters, used to screen crude oil and natural gas, among piles of regular garbage when the dioxin tests were conducted. But Taam doesn’t think they were a factor.
The Canadian filters “have always been in the (trash-burning) mix for the past four years,” he said.
The city agreed this month to stop accepting Canadian oil field debris as part of a new agreement with SCAPCA and Washington state officials on what can be burned in the plant.
SCAPCA was concerned the “special waste” discards, which also included imported pesticide jugs, would increase toxic air emissions at the plant.
The higher-than-normal dioxin levels showed up in one of the plant’s two burners in late September and early October. The average was .506 nanograms.
The first test in Unit 1 produced readings of .685 nanograms. The lowest level of dioxin measured was .299 nanograms.
Unit 2 averages were far less, .014 nanograms, the report says.
The dioxin tests were conducted by AmTest-Air Quality of Preston, Wash.
Other pollutants measured in the same tests, including carbon monoxide and nitrogen oxides, all were well below permit limits.
Dioxin isn’t monitored continuously at the Spokane plant. The annual measurements are projected for the entire year to estimate how much of the chemical the incinerator produces.
Critics say the test can underestimate actual emissions because it’s done under ideal conditions. Defenders say the tests are representative of what the plant burns most of the time.
If the higher dioxin levels in Unit 1 were projected for all of 1998 for both burners, the plant would eject .6544 grams of dioxin this year, according to SCAPCA calculations.
SCAPCA’s dioxin limit for the trash incinerator is now nine times more stringent than when the plant first went on line in 1991.
Environmental groups appealed the initial limit to the state pollution control hearings board. The board agreed the standard was too lax.
The board said the dioxin limit should be set as low as the plant’s pollution controls could handle. The current standard took effect in August 1995.
A new federal standard based on a seven-year scientific review of dioxin’s health effects is expected by the end of 1998 and is expected to be more stringent.
In a 1994 report, the EPA said some adverse health problems from dioxin were induced in laboratory animals at levels “at or near” what people are already being exposed to in the environment from trash incinerators, chemical plants and other sources.
The EPA also said dioxin accumulates in the food chain, and exposure of infants through breast milk is an especially important pathway.
A $300,000 environmental risk study of Spokane’s trash incinerator, now two years overdue, does not address the breast milk issue, ignoring the recommendation of state Department of Ecology officials.