Clean Water Advocacy - Newsroom - AMSA in the News
No. 229
Friday, November 30, 2001 Page A-3
ISSN 1521-9402
News
Water Pollution
Average Dioxin Levels in Biosolids Lower Than Proposed EPA Limits, Survey Shows
The average concentration of dioxins and dioxin-like compounds in municipal
sludge is much lower than a threshold level proposed by the Environmental
Protection Agency in 1999, municipal waste water treatment officials said in a
report released Nov. 29.
The Association of Metropolitan Sewerage Agencies' 2000/2001 Survey of
Dioxin-like Compounds in Biosolids: A Statistical Analysis shows a mean
concentration of dioxins in biosolids of 48.5 parts per trillion toxic
equivalents (TEQ). The study is based on a voluntary survey of 171 publicly
owned treatment works in 31 states and considered 200 samples.
The dioxins and dioxin-like compounds include seven polychlorinated dibenzo-p-dioxins,
10 polychlorinated dibenzofurans, and 12 dioxin-like coplanar polychlorinated
biphenyls.
EPA proposed in December 1999 to prohibit the land application of sludge with
dioxin concentrations exceeding 300 parts per trillion (242 DEN A-8, 12/17/99).
The so-called Part 503 Sewage Sludge Use rule under the Clean Water Act also
will contain monitoring and recordkeeping requirements. EPA was under court
order to issue the rule by Dec. 15, and agency officials have said they would
consider the survey data in the rulemaking. However, the court agreed to extend
the deadline to March 1, 2002, to allow EPA time to consider new data. The
agency is expected to rely primarily on its own data, although officials have
said they would look at the AMSA data.
The survey showed the median concentration was 21.7 ppt-TEQ. The 200 samples
showed a range of concentrations from 7.1 ppt-TEQ to 256 ppt-TEQ. One sample
came in at about 3,590 ppt, the survey said.
Survey Discussed at AMSA Meeting
The preliminary survey results were discussed at AMSA's summer meeting in July
(138 DEN A-15, 7/19/01).
At the meeting Alan Hais, associate director of the health and ecological
criteria division of the EPA Office of Water, said that while exposure to
dioxins and other compounds is a concern to the agency as it contemplates the
final rule, other hazards from the land application may be more of a problem.
EPA expects to issue in early 2002 its assessment of the risks dioxins pose in
the environment. The assessment is currently undergoing an internal review and
could be considered in the final 503 sludge rule, EPA officials said in October.
Overall, Hais said, the agency's own studies, as well as those by AMSA, show
very small quantities of dioxin in sewage sludge.
"But we're concerned about the exposures in the environment," Hais said in July.
He could not be reached for comment Nov. 29.
Average Concentration Declined
The AMSA survey also revealed that the average has declined somewhat from levels
found in a 1994-1995 survey. For example, the median dioxin/furan TEQ dropped 56
percent during that time period when adjustments were made to account for
various factors, the survey said. The median PCB subset concentration fell more
than 80 percent, the survey said.
Nancy Girard, an attorney with Conservation Law Foundation, told officials at
the July AMSA meeting that the data collection activities to measure
concentrations of dioxins were inadequate.
"We still don't know the impact of bioaccumulation," she said.
She also said it was important to consider the impacts of the land application
of biosolids on groundwater. She encouraged municipalities to conduct more
public information programs on the land application of biosolids.
The AMSA survey showed there may be some variation in dioxin concentrations in
biosolids among different EPA regions, but said more study was needed on that
issue.
By Susan Bruninga