PUBLIC HEALTH CONCERNS RELATED TO DIOXIN

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1 PUBLIC HEALTH CONCERNS RELATED TO DIOXIN Robert G. O Dette Mr. O Dette holds a B.S. and M.S. in Civil (Environmental) Engineering and has more than 25 years of experience in wastewater treatment, and residuals and biosolids management. He is a registered professional engineer and a Diplomate of the American Academy of Environmental Engineers. Mr. O Dette has testified before the U.S. Congress and is Chair of the Water Environment Federation s Residuals and Biosolids Committee. Address: Synagro Technologies Inc., Yadkin Valley Road - Advance - North Carolina USA - Tel: (336) Fax: (336) bob@biosolids.com ABSTRACT There is a growing world wide concern over dioxin and its presence in many substances including biosolids. Some of the questions to be answered are "How dangerous is dioxin?" and "Is there a human health risk associated with dioxin/furans in biosolids?" This paper examines these questions and provides additional information relative to established and proposed regulations in the United States for dioxin. KEYWORDS: Dioxin, Furans. Biosolids. Toxic Equivalency, Human Carcinogen, Health Effects. INTRODUCTION Dioxin is a generic term for polychlorinated-para-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). [RTP, 1997] Dioxin is a colorless, odorless organic compound containing carbon, hydrogen, oxygen and chlorine. The term dioxin refers to a broad family of chemicals, which differ from one another by the location and number of chlorine atoms on the molecule. [ 1997] It is important to note that whether the substance is a dioxin or a furan the numbering sequence identifies the positions of the chlorine atoms. The term "dioxin" has actually become an abbreviation with different meanings. First, it is used to describe a family of 210 almost planar aromatic compounds. The family encompasses 75 PCDD congeners and 135 PCDF congeners (a "congener" means the same kind or class). Moreover, "dioxin" is often used to refer to one particular isomer from this collection of 210 possible compounds (an "isomer" is any of two or more chemical compounds having the same constituent elements in the same proportion by weight but differing in physical or chemical properties because of differences in structure of their molecules). [RTP, 1997] The term "dioxin" is increasingly becoming associated with a subset of the two families of compounds: PCDD and PCDF. There are 17 members of this subset which are characterized by the presence of chlorine atoms in the 2,3,7 and 8 positions. Each of these 2,3,7,8-substituted PCDD or PCDF congeners has been assigned a Toxic Equivalent Factor 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4313

2 (TEF), which is used for the computation of the Toxic Equivalency (TEQ). [RTP, 1997] The TEFs represent an international toxicity equivalency factor (I-TEF) method of risk assessment for complex mixtures of dioxins and related compounds developed in 1988 by the North Atlantic Treaty Organization's Committee on the Challenges of Modern Society. These l-tefs were adopted by the U.S. EPA as TEFs in 1989 and are contained in the document entitled: "Interim procedures for estimating risks associated with exposures to mixtures of chlorinated dibenzo-p--dioxins and dibenzofurans (CDDs and CDFs) and 1989 Update," (EPA/625/3-89/016). DETECTION AND QUANTIFICATION Analytical results for dioxin are normally reported in terms of parts per trillion (ppt) or parts per quadrillion (ppq). One ppq is about the same as one second in 30 billion years, so the technology to analyze for dioxin is very sophisticated. Quality analytical detection for dioxins and furans is done through the use of high resolution mass spectrometry (HRMS) analyses. The theoretical target detection limits for HRMS in a biosolids, sludge or soil matrix is 1 ppt (dry weight). However, actual detection limits may be lower depending upon the situation. [RTP, 1997] United States Environmental Protection Agency (USEPA) Methods 1613A and 8290 are used in conjunction with HRMS. Method 1613A is recommended by Dr. Alan Rubin, USEPA, [Rubin, 1994] but Method 8290 mav have to be used if serial dilutions are reauired. The toxicity equivalent of a material is calculated by first multiplying all of the concentrations (ppt) of the isomers by their appropriate TEF. This will give a TEQ for each isomer. The sum of these TEQs will be the total equivalency of the material relative to 2,3,7,8-TCDD. The TEF for 2,3,7,8 TCDD is 1.0, so the TEQ is an attempt to quantify all dioxins and furans in terms of 2,3,7,8 TCDD through an extrapolation process. Table 1 shows the various TEFs for the different isomers. Analytical results can be reported in two ways: (1) TEQs calculated for only those isomers detected, or (2) TEQs calculated for those isomers detected plus TEQs for the other undetected isomers using one-half the detection level as the multiplier with the appropriate TEF for that isomer. Table 1: TEF for Dioxin / Furan Isomers. ISOMER T E F 2,3,7,8 - TCCD 1.0 1,2,3,7,8 - PeCDD 0.5 1,2,3,4,7,8 - HxCDD 0.1 1,2,3,6,7,8 - HxCDD 0.1 1,2,3,7,8,9 - HxCDD 0.1 1,2,3,4,6,7,8 - HpCDD ,2,3,4,6,7,8,9 - OCDD ,3,7,8 - TCDF 0.1 1,2,3,7,8 - PeCDF ,3,4,7,8 - PeCDF 0.5 1,2,3,4,7,8 - HxCDF 0.1 1,2,3,6,7,8 - HxCDF 0.1 2,3,4,6,7,8 - HxCDF 0.1 1,2,3,7,8,9 - HxCDF o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4314

3 ABBREVIATIONS: 1,2,3,4,6,7,8 - HpCDF ,2,3,4,7,8,9 - HpCDF ,2,3,4,6,7,8,9 - OCDF TCDD tetrachlorodibenzo-p-dioxin TCDF tetrachlorodibenzofuran PeCDD pentachlorodibenzodioxin PeCDF pentachlorodibenzofuran HxCDD hexachlorodibenzodioxin HxCDF hexachlorodibenzofuran HpCDD heptachlorodibenzodioxin HpCDF heptachlorodibenzofuran OCDD octachlorodibenzodioxin OCDF octachlorodibenzofuran For example, the National Sewage Sludge Survey (NSSS) conducted by the USEPA in the United States in 1988 [USEPA, 1990] indicates that the median value of total equivalents of dioxin in biosolids is between 9 and 50 ppt, depending on which of these two reporting methods is used. In any event, the final determination of analytical method and TEQ reporting should be worked out on a case-by-case basis with the laboratory and so noted on all laboratory data and/or information sheets. SOURCES AND PATHWAYS The largest single source of chlorine use is in the manufacturing process of polyvinyl chloride plastics (PVC). Other sources of chlorine are in chlorinated solvents, chlorinerelated pesticides, chlorinated inorganic and organic chemicals, metallurgy, wastewater treatment and remediation, all of which have dioxin associated with it in some way. [Sludge, 1994] One manufacturing process for pesticides uses 2,4,5-trichlorophenol (TCP) to make 2,4,5-trichlorophenoxyacetic acid (2,4,5 T). The production of TCP is a major route for the formation of dioxin and the source of the contaminant in 2,4,5 T, also known as Agent Orange. [C&EN, 1984] The potential for dioxin to contaminate water is slight because of its hydrophobic characteristics. The dioxin molecule has a great affinity to organic matter and soil particles. Any contamination of lakes, rivers, streams, or other water bodies would most likely occur in the sediment or be attached to particulates suspended in the water. [RMWEA, 1994] Contamination of food sources by biosolids containing chlorinated dibenzo(p)dioxin (CDD) and chlorinated dibenzofurans (CDF) would be relatively small. Thirty-six 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4315

4 percent of all biosolids produced in the nation are land applied, and less than two percent of the nation's crops are grown in soil fertilized with biosolids. [SIudge. 1995] It is thought that the leading cause for TCDD to enter the terrestrial food chain is via atmospheric deposition from several combined processes. [EST, 1995] The route of entry for animals and humans is by ingestion, inhalation, and percutaneous (through the skin). Background levels in the human population average 40 to 60 ppt. Dioxin toxicity is both tissue- and species-specific, the mechanism(s) of action (entering a cell) seem to involve an initial interaction with an intracellular binding protein, termed the Ah-receptor or dioxin receptor. [Huff, 1994] As in animals, dioxin is stored in human adipose (fatty) tissue. Through industry efforts to reduce dioxin, levels in humans have declined considerably in the last several decades. A recent study conducted by the Centers for Disease Control and Prevention indicates that dioxin levels in Americans have declined from 18 ppt in 1976 to less than 5 ppt. [ 1997] Scientist recognize that the effects of dioxin vary widely among different animal species. Humans are less susceptible to the consequences of dioxin exposure than many of the animal species tested in laboratories. For example, reproductive effects seen in rats and rodents due to dioxin exposure have not been found in primates. [ 1997] There are no documented cases that human exposure to dioxin and/or furans has resulted in cancer, cardiovascular diseases, or ischemic (lack of blood supply) heart diseases. Most research in humans has involved populations involved in occupational or accidental exposures of dioxin several thousand times higher than normal. For example, residents of Seveso, Italy were exposed to dioxin following an industrial accident in 1976 and in over 20 years, the only documented health problem for these people has been chloracne, a skin disorder resembling teenage acne. Very few studies have examined the health effects of dioxin on the general population. However, based upon available data, many scientists do not expect adverse health effect from normal exposures. [http: 1997] In a statement on May 10, 1994, Dr. Lynn Goldman, USEPA Assistant Administrator of Prevention, Pesticides and Toxic Substances concluded that it should be stressed that the benefits of a balanced, nutritional diet far out weigh any risks from dioxin to the general population. [ 1997] Dr. Goldman, a pediatrician, has stated that the benefits of breast feeding far out weigh any dioxin-related risks. [ 1997] A few years ago when Assistant Surgeon General of the United States, Vernon N. Houk downplayed the health threat of dioxin by calling it a "weak" carcinogen, his comment raised eyebrows throughout the scientific and regulated communities not simply because he was a top official at the Centers for Disease Control (CDC). His opinion held additional weight because it was Houk himself who had ordered the permanent evacuation of dioxincontaminated Times Beach, Missouri, USA, in the early 1980's. Houk said progress made since then in understanding dioxin had convinced him the decision was wrong. [Krukowski. 1992] Houk has said, "the evidence is that dioxin is not a carcinogen in the population exposed to lower doses." "If it is a human carcinogen at high-dose exposure, it is a weak one, and the risk is not of the same order as that for workers exposed to asbestos, radon, nickel, coke and chromates." Houk has said he did not regret his Times Beach decision: "Given the same 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4316

5 conditions, I would do the same thing today." But he added that the state of science today leads him to believe the government can relax somewhat the amount of dioxin it says humans can safely ingest. [Krukowski, 1992] How much dioxin is deadly remains an unanswered question. Table 2 shows a comparison of tolerable daily limits of dioxin, as established by health and regulatory agencies, to the average human daily intake. [Krukowski, 1992] Table 2: Tolerable Daily Limits of Dioxin. GROUP Daily Intake Level picograms per kg of body weight USEPA 0.006* Centers for Disease Control (CDC) 0.03* World Health Organization (WHO) 10.0* *Recommended value Average Human up to 30.0 Since 1985, EPA's acceptable daily intake of dioxin for humans has been a minuscule picograms per kilogram (kg) of body weight, which is meant to represent a one-in-amillion cancer risk (10-6 ). Houk noted that most citizens of industrial countries ingest anywhere from 2 to 30 picograms per kg per day, or up to 4,800 times the risk level. Indeed, many other western nations have set much higher limits than has the United States, and the World Health Organization (WHO) has put the magic number at 10 picograms per kg per day. [Krukowski, 1992] Houk is not alone in questioning dioxin's threat. Dr. William H. Wolfe, chief of epidemiological research at Armstrong Laboratory, Brooks Air Force Base, Texas, says his work with the "Ranch Hand" study of Vietnam War-era veterans exposed to dioxintainted herbicides has persuaded him that dioxin is "not the cause of cancer everyone thought it is--people can lessen their fears. We're not seeing a lot of the evidence of the catastrophic illnesses we expected." [Krukowski, 1992] Dr. Alan B. Rubin, USEPA, has said, "Dioxin is present throughout the environment. Based on the best information available today plus a preliminary estimation of the dioxin levels present in biosolids, there is nothing to suggest that the dioxin level in biosolids is anything less than safe for both human health and the environment." [Rubin, 1994] REGULATORY ISSUES In the United States, the only state that currently has a dioxin requirement, relative to the land application of municipal biosolids, is the State of Maine. Maine's requirements for dioxin are based upon TEFs. The State of Maine requirement is 27 ng/kg (parts per trillion) for biosolids to be land applied without site restrictions (relative to dioxin application rates) with a maximum allowable concentration of 250 ng/kg. For comparison, the State of Maine's criteria of 27 ng/kg and 250 ng/kg is similar in concept to EPA's pollutant concentration (Table 3 of ) and ceiling concentration (Table 1 of ) values, respectively, contained in the USEPA's 40 CFR Part 503 regulation. 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4317

6 The NSSS gives the results for the analyses of all dioxins/furans in terms of TEF/TEQ. A summary of the NSSS for dioxin is given in Table 3. [USEPA, 1990] Table 3: Dioxin Levels Reported in the USEPA's NSSS. PARAMETER Mean Maximum Percent POTWs Greater than 27 (%) Dioxin (TEQ) , ,3,7,8 - TCDD NA Also, noted in Table 3, is the fact that if one uses the State of Maine criterion for dioxin of 27 ng/kg, it can be shown that 32 percent of the POTWs surveyed do not meet this requirement. [O'Dette, 1995] Notice in Table 3 that only 2 percent of the POTWs surveyed would have failed the Maine requirement, if 2,3,7,8 TCDD were the only isomer considered. This point is amplified by Table 4 which shows a comparison of NSSS data for Corinth, Mississippi (POTW with the highest level of the specific isomer 2,3,7,8 TCDD in the NSSS) and Billerica, Massachusetts (POTW with the highest level of total equivalency in the NSSS). Table 4: Comparison of Dioxin Levels for Two Cities Included in NSSS. P O T W (USA) 2,3,7,8 - TCDD Total Equivalency Corinth, Mississippi 116 1,514 Billerica, Massachusetts NA 2,267 From this one can see the significance of using the TEF or total dioxin/furan levels versus one specific isomer. [USEPA, 1990] CONCLUSIONS The conclusions in the dioxin reassessment are based on 2,3,7,8 TCDD, approximately 80% to 90% of the TEQs are from congeners other than 2,3,7,8 TCDD. The USEPA has been criticized for extrapolating primarily the results from in vitro analyses, or even structural activity relationships (SAR) across various species when few of the congeners other than 2,3,7,8 TCDD have actually been tested for toxicity. [Cooper, 1994] In essence, the data base does not exist to support any concerns over dioxin/furans in biosolids. It is imperative that any regulations dealing with dioxin/furans represent good science. 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4318

7 BIBLIOGRAPHIC REFERENCES 1. "Dioxin/Furan Analysis," Information Sheet prepared by Triangle Laboratories, Inc., Research Triangle Park. NC (March ). 2. "Questions and Answers about Dioxin and Food Safety," (June 7, 1997). 3. "Greenpeace: EPA Review of Dioxins Underestimates Chemicals' Sources," The Sludge Newsletter, August "Dioxin Report, a C&EN Special Issue," Chemical & Engineering News, Vol. 61, No. 23, pp , June Draft Fact Sheet on Dioxin prepared by the Biosolids Committee of the Rocky Mountain Water Environment Association (94-FS-18). 6. "Dioxin from Sludge Incineration Should be Low Priority for EPA," The Sludge Newsletter, p.37, February "Dioxin Risk: Special Report," Environmental Science and Technology, Vol. 29, No. 1, pp. 24A- 35A, HUFF, J., LUCIER, G., TRITSCHER, A., "Carcinogenicity of TCDD: Experimental, Mechanistic, and Epidemiological Evidence," Annual Review of Pharmacology Toxicology, Vol. 34, pp KRUKOWSKI, JOHN, "Cracking Dioxin's Secrets," Special Report-Pollution Engineering, January 15, CFR Part 503, National Sewage Sludge Survey; Availability of Information and Data and Anticipated Impacts on Proposed Reaulations; Proposed Rule; Federal Register Friday, November RUBIN, ALAN B., Press Advisory, RE: Dioxin in Biosolids, April 21, O'DETTE, ROBERT G., "State Regulations Impacting Industrial Residuals Management," Preconference Workshop Proceedings - Industrial Waste Residuals, WEFTEC '95 Conference and Exposition, Miami Beach. Florida (Sunday. October ). 13. COOPER, GAIL A., MEMORANDUM - "Dioxin Reassessment Update No. 3, Water Environment Federation, Alexandria, VA (December 21, 1994). 20 o Congresso Brasileiro de Engenharia Sanitária e Ambiental 4319