Member Pipeline - Regulatory - Alert (RA 01-19)

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To: Members & Affiliates, Legal Affairs Committee
From: National Office
Date: November 29, 2001
Subject: AMSA 2000/2001 SURVEY OF DIOXIN-LIKE COMPOUNDS IN BIOSOLIDS
Reference: RA 01-19

Final Report

AMSA is pleased to present the final AMSA 2000/2001 Survey of Dioxin-Like Compounds in Biosolids: Statistical Analyses (Final Report), which demonstrates that levels of dioxin-like compounds in biosolids are on average well below EPA’s proposed 1999 limit and have declined since the previous AMSA survey was conducted in 1994 and 1995. The Final Report marks the culmination of a voluntary survey AMSA began in October 2000 to determine current levels of dioxin and dioxin-like compounds (including seven polychlorinated dibenzo-p-dioxins, ten polychlorinated dibenzofurans, and twelve dioxin-like coplanar polychlorinated biphenyls (PCBs)) (hereinafter dioxin) in biosolids.

AMSA thanks all the agencies that participated in this survey, which is likely the most comprehensive investigation into dioxin levels in biosolids to date. Without the participation of AMSA member agencies and other POTWs across the country, this effort would not have been possible.

AMSA’s survey was triggered in part by the U.S. Environmental Protection Agency’s (EPA’s) December 23, 1999 proposal of a 300 parts per trillion (ppt) toxic equivalents (TEQ) level for land-applied biosolids under a Consent Decree involving AMSA, environmental groups, and EPA (Gearhart v. Whitman). In developing the proposed regulation, EPA used historical data from its 1988 National Sewage Sludge Survey and AMSA’s 1994/1995 Survey of Dioxin-like Compounds in Biosolids. Although EPA’s risk analysis for the proposed limit of 300 ppt-TEQ assumed that levels of dioxin-like compounds in biosolids were remaining constant or diminishing, AMSA believed there was a need for current data to further support this assumption. AMSA also wanted to assess overall trends in concentrations of dioxin-like compounds in biosolids since AMSA’s 1994/1995 Survey of dioxin in biosolids. AMSA’s data will assist EPA in its efforts to finalize an environmentally sound and technically based regulation for dioxin in land-applied biosolids.

Key conclusions of the Final Report include:

Concentrations of dioxin in biosolids in AMSA’s 2000/2001 Survey have declined from the 1994/1995 Survey;

• The average dioxin concentration in AMSA’s 2000/2001 Survey is 48.5 ppt-TEQ. All but one of the 200 samples from the survey would comply, and most go well beyond compliance with the proposed regulatory standard of 300 ppt-TEQ;
• The median dioxin concentration of the samples in AMSA’s survey is 21.7 ppt-TEQ, more than one order of magnitude below the proposed regulatory limit; and
• Evidence from the survey suggests there may be some variation in dioxin concentrations in biosolids among EPA Regions, but further study will be needed to fully test such a hypothesis and demonstrate that such variation is not an artifact of the sampling method or simply random variation.

The Final Report and associated appendices can be found on AMSA’s web site at:
http://www.amsa-cleanwater.org/advocacy/dioxin/dioxin.cfm.

Details on AMSA’s 2000/2001 Survey
As indicated above, AMSA began its voluntary survey to determine current levels of dioxin in biosolids in October 2000. On July 12, 2001 AMSA met with EPA to discuss the preliminary results of the survey and to provide EPA with preliminary data to supplement the results EPA had obtained from its own recent survey of dioxin in biosolids. AMSA also presented these preliminary findings to the membership at the 2001 AMSA Summer Conference. Since that time, AMSA has worked with our survey consultant Cambridge Environmental, Inc. to conduct a final quality assurance/quality control review of the survey data and to prepare a comprehensive report of the findings.

Overall, 111 separate wastewater treatment agencies participated in the 2000/2001 AMSA Survey, providing 200 samples from 171 POTWs, located in 31 states. A review of the new survey data reveals that the dioxin concentrations of the 200 biosolids samples ranged from 7.1 ppt-TEQ to 256 ppt-TEQ, with one outlier at 3,590 ppt-TEQ. As stated above, the mean (average) concentration was 48.5 ppt-TEQ, while the median concentration was 21.7 ppt-TEQ. All but one of the samples from the 2000/2001 Survey would comply with a regulatory standard of 300 ppt-TEQ. Notably, the median dioxin concentration of the samples is more than one order of magnitude below the proposed regulatory limit.

A summary of the 2000/2000 data is contained in Table A.

Table A  Statistics for TEQ Data^A (ppt-TEQ)

	Non-detects set to one half the detection limitB
	Total	Dioxins and Furans	PCBs
Average (Mean)	48.5	38.4	10.0
Minimum	7.10	5.94	0.54
10th Percentile	9.65	7.55	1.75
25th Percentile	13.09	9.55	2.99
Median	21.67	15.15	5.70
75th Percentile	36.00	24.81	10.06
90th Percentile	54.00	37.36	16.98
95th Percentile	88.07	53.24	28.14
99th Percentile	226.12	118.28	81.04
Maximum	3590.05	3578.61	228.65

A EPA has proposed a 300 ppt-TEQ limit for land applied biosolids, using the International toxicity equivalency factors (TEF) scheme for the seventeen 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans congeners, and the World Health Organization’s (WHO) TEF scheme for the twelve coplanar PCBs.  However, data in Table A was developed using the more conservative WHO scheme for all dioxin-like compounds.  B EPA has indicated that all non-detected congeners will be assumed to be present at one-half of the detection limit in the final rule.

 
Comparison of AMSA 1994/1995 Data and 2000/2001 Data
AMSA compared data from its 2000/2001 and 1994/1995 surveys to determine if there has been a statistically significant change in the dioxin levels reported by POTWs.

In the 1994/1995 Survey there were a total of 104 sample analyses from 75 separate facilities. Five of the samples had biosolids concentrations of less than 0.1%. These were omitted from further consideration as not being representative of biosolids, leaving 99 sample analyses from 74 separate facilities.

Table B contains a comparison of the data from AMSA’s 1994/1995 and 2000/2001 surveys.

Note: Since the 1994/1995 data was developed with non-detects “at zero” and “at the detection limits,” this comparison (in Table B) does not contain a comparison with non-detects “at one half the detection limits.

Overall, these results help to confirm that concentrations of dioxin in biosolids are declining. Although we were not able to conduct a review of dioxin concentrations on a facility-by-facility basis (between the two surveys), a comparison of the results does indicate that the averages (means) and medians of the data are lower in the 2000/2001 data set than in the 1994/1995 data set. When non-detected congeners are assumed to be absent, the median dioxin/furan TEQ concentration declined by 56%, the median PCB subset TEQ concentration (containing only those PCB congeners analyzed in the 1994/1995 survey) declined by 83%, and the median adjusted total TEQ mass fraction declined by 64%. The corresponding averages declined by 0.5%, 79%, and 32%, respectively. Thus, it appears the decrease in average total TEQ between the two sets of survey results is driven by declining PCB concentrations.

Next Steps
AMSA will provide EPA with the Final Report and the raw survey data. Although EPA will rely primarily on its own survey data when conducting the risk assessment for the final rulemaking, EPA has indicated that the results from the AMSA survey will be helpful in developing the final regulation.

EPA is required to finalize the regulation for dioxin in land-applied biosolids by December 15, 2001 under the Consent Decree. However, in addition to AMSA’s now available Final Report, EPA itself has collected significant new data on dioxin in biosolids since the rule was proposed in December 1999. EPA also is conducting a new risk assessment to support the final rule. Accordingly, AMSA and the Consent Decree parties have extended the December 15 deadline for EPA to complete the rule until March 1, 2002. In addition, in Spring 2002 EPA is expected to approve a new and significantly more stringent Agency-wide cancer value for dioxin. EPA plans to use this new value, if approved, in the land applied biosolids rule. The use of this new cancer value is expected to significantly impact EPA’s risk assessment for the rule. Since March 1 is likely unachievable given the volume of new scientific information, AMSA and the parties continue to negotiate a further extension of the deadline beyond March 1. AMSA anticipates that a longer extension will be agreed upon, and that there will be additional notice and comment opportunities for the membership on this new scientific information and other developments since the rule’s proposal in December 1999.

AMSA will report to the membership when our negotiations successfully establish a new deadline for EPA to complete this regulation. At that time, we will outline the process for additional notice and comment and AMSA’s plans for developing comments. These plans include comprehensive reviews of EPA’s survey data, assessment of the impact of the new dioxin cancer value, and evaluation of EPA’s new risk assessment model to ensure the final regulation is realistic and scientifically sound.

It is important to note that under the same Consent Decree, EPA is expected to finalize by December 15, 2001 a regulation establishing no dioxin limit for landfilled or incinerated biosolids. We do not anticipate any delays in EPA meeting this deadline for these two biosolids options.

For More Information
If you have any questions or require additional information concerning the survey or the Final Report, please do not hesitate to contact Robert P. Dominak, Co-Chair, AMSA Biosolids Management Committee at 216/881-6600 or Chris Hornback, AMSA at 202/833-9106 or chornback@amsa-cleanwater.org. For questions on the dioxin litigation, contact Alexandra Dunn, AMSA’s General Counsel at 202/533-1803 or adunn@amsa-cleanwater.org.

 

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