JUN UJ. 1558 American Paper Institute, Inc. 200 Manson menu. New writ. NY. ummam mow-m (Nah: mum's-i: 315%st New ?at (31mm 'n'sulml May 27, 1988 Dear Reporter: Over the last few months, API has provided you with the results of several research activities the industry had underway as independent projects or in cooperation with the U.S. Environmental Protection Agency. As you may recall; these activities were begun following the unexpected discovery of previously undetectable trace amounts (parts per trillion and quadrillion) of dioxin in some bleached pulp and paper mill treated effluent, sludge and pulp. All of the research completed to date confirms that the products made with the bleaching process are safe, as is the workplace in which they are manufactured. Today, I wanted to provide you with the results of additional projects just completed. They include the release of the final report on the Joint EPA/Industry Five-Mill Screening Study: the research plan submitted by the industry to EPA for an intensive industry study of 25 mills: and results of bleached coffee filter tests and preliminary findings of the employee dermal exposure tests. sum mm :Jw rum: ?and um! um} unlit-?m 1 I Joint BPA?Induetgy Five?Mill screening Study- The results of this"joint testing program were provided in September 1.937, and pm this week has Completed and released the_fina1 study dosiment. As was reported earlier. the joint five-mill screening study was entered into when trace amounts of dioxin werelunexpectedly found in fish i samples taken from some pulp and paper mills. _screening study confirmed the presence of dioxin in the previously undetectable low-?arts per trillion in some ofzthe bleached pulp samples and in the sludge, and in the parts per guadrillion in some of the treated effluent samples. (As a point of reference, one part per trillion is equal to one second in 32,000 years, one part per guadrillion is equal to one second in 32 million years.) The study identified the bleaching process as the source of the traces of dioxin, but did not determine the precise point or method of formation. (See attached Executive summary for further details.) To obtain a more complete picture, last month_EPA and the industry agreed to coordinaJe testing for trace levels of dioxin at all 0.8. mills bl aching chemical wood pulp with chlorine or chlorine derivatives. under the joint agreement, announced in our April 22 news release, samples of sludge, wastewater and bl?eached pulp will be tested from over 100 mills across the nation. 9.4 1'Twenty-Five Hill_;ntansivo study This week the industry also proyided to EPA the proposed research plan for an intensive of 25 of the over 100 mills to be tested as part of the? worky'described above. The intensive study will examine such[variables as level of chlorine use, the impact of oxyge% delignification, paper 1 grades produced, operational practices and process differences. This study is specifically designed to help in isolating which elements of the process are most important in defining meaningful technology options. EPA is reviewing the proposal and will have the opportunity to suggest revisions. Currently, we know of no commercially-available bleaching process which would totally eliminate the low levels of.dioxin found in the samples tested to date. Bleached Coffee Filter Tests This week, the industry_is also releasing the results of 'tests conducted on coffee filters. The 30-page document. "Assessment of the Risks Associated with Potential Exposure to Dioxin Through the Consumption of Coffee Using Bleached Pulp-Based Filters," confirms that the risk to consumers from use of bleached coffee filters in coffee-making and consumption is below the one-in-a?million risk level used by 3E::j? the government to determine a virtually safe done. I The study tested real coffee filters, and used brewed coffee to model a variety of coffee?making situations -- home, office, restaurant and institutional. Using conservative assumptions, coffee consumption patterns of the upper 10 percent of coffee drinkers over a 55?year period (the average i . number of years coffee is consumed for a 70-year life span), the.testing confirmed that bleached coffee filters are safe. Testing and analytical work were done by California Analytical of Sacramento, CA, and the National Council of the Paper Industry for Air and Stream:Improvement (NCASI), the industry?s independent research organization. The risk assessments used coffee consumption data from the United States of America Coffee Drinking Study, winter 1987, and the Food and Drug Administration's potency factor for dioxin. (See attached Executive Summary for further details.) Workplace Dermal Study i Also available this week were preliminary findings of "Assessment of Potential Health Risks to Pulp and Paper Mill Workers from Dermal EXposure to Dioxin in Bleached Pulp, Paper and Pulp?Based Products," an examination of the role of skin contact with bleached products in thelworkplace. The preliminary results indicate that the actual risk to employees from dermal exposure to the very low concentrations of dioxin and related compounds in bleached pulp, paper, and pulp-based 3 products is significantly less than the one-in?a-million risk level used by the government to determine a virtually Safe dosezero. the final report will be i available within a few weeks. (See attached Executive Summary for further details.) Earlier studies on worker exposure via paper dust inhalation produced similar encOuraging results. The release of-this information reflects the industry's continued commitment to keeping ali interested parties fully informed of our activities and to resolving this issue in an open and forthright fashion. The results released today and the research work underway use the most sophisticated science 1 available. They continue to aSSure consumers that they can enjOy the convenience of paper products just as they have in the past, that our workplaces are safe, and that the industry is committed to finding how the dioxin is being formed. If you would like further information or copies of any of the studies conducted, please feel free to'contact me. Sincerely, Red Cavaney Rc:rfp Enclosure if) 1115. ENVIRONMENTAL . . . . . . . EXECUTIVE SUMMARY - As a result of the National Dioxin Study findings of tetrachlorodibenzo-p?dioxin (2373-TCDD) in native fish collected from a number of pulp and paper mills and subsequent findings of in bleached kraft pulp and paper mill waste-water sludges, the United S-ates Environmental Protection Agency (USEPM planned a detailed process eValuation study at one .mil'l. Through subsequent discussions with the paper: industry, USEPA and the industry agreed in June 1986 to'conduct a cooperative .screening study of five bleached kraft pulp and paper mills on a shared resource basis. Three mills were selected on the basis of .. known 2378-TCDD levels in sludges and two mills were volunteered by their parent companies to attain the geographical diversity desired for the study. The selection of the five mills, which 'represent about 6 peL'Cent of the bleached kraEt mills in the United States, was not intended to characterize the entire industry. The principal objectives of the study were: Determine, if present, the source or sources of 2378-1133;) and other dibenzo-p-dioxins (Pcoos) and dibenzofurans at five bleached kraft pulp and paper mills;I and 2. the untreated-wastewa-ter discharge loadings final effluent discharge loadings, sludge concentrations, and wastewater treatment system efficiency for and other poses and moss. - 1 Field work for the five?mill study was conducted during the period June l986?January 1.987 through the combined efforts of four USEPA regional offices, five state environmental control agencies, the National Council ?of the Paper Industry for Air' and .Stream Improvement, Inc. (NCASI) and the participating paper companies. The analytical methods development program and analyses of samples for selected and were conducted at the Brehm Laboratory, ralright State University. Selecteid samples were analyzed for certain chlorinated phenolics by NGASI. This report is limited to presentation of the complete data and the scientific and technical findings resulting from the cooperative study. Consideration of public and Occupational heilthienvironmenta'l?, consumer product, medulatorv 5.55655 that may; be associated with study findings is beyond the scopTo?E tw. Additional research is being plannememon'ted by wt}: government and industry to deal with such issues. To accomplish the first study objective, it was necessary to design a general comprehensive study plan of all major and minor mill inputs, intermediates, and mill The general plan was modified as necessary to conform to the specific circumstances of each mill. Because chlorine and chlorine derivatives are first introduced in substantial quantities in the bleaching process. emphasis was placed on detailed process sampling in bleacheries. The principal mill exports sampled were bleached pulps, treated process wastewater effluents, and wastewater sludges dewatered for' disposal. Although bleached pulps are econverted into paper products at each mill, bleached pulps were considered mill exports for purposes of this study. This eliminated the need to sample and quantify mass outputs of numerous paper machines which were not always related to bleachery operations during field sampling. The second objective was addressed by sampling combined untreated wastewaters, intermediate and final wastewater sludges, and treated process wastewater effluents. Evaluationcafnoncontact cooling waters and possible atmospheric anissions were not included in the Study design. Initially, the analytical program required, where possible, tor each sample, isomer-specific analyses of tetrachloro dibenzo-p? dioxins and tetrachlorodibenzofurans and, where possible, for selected samples, isomer-specific analyses of 2378- substituted pentae through hepta?- C005 and C095, and 0CDD and' 0CDF. However, based upon analysesiof a limited number of prelimi- -nary samples and a limited number of USEPA analyses of samples from other mills, the scope of the analytical program was reduced. The preliminary analyses indicate that 2378-TCDD and are the principal and found in the pulp and paper mill matrices, particularly when considered in light of USEPA's 2378? TCDD toxicity equivalents approach. Accordingly, all samples were analyzed for and 2378-TCDE, since the extensive analytical methods development work required for isomer-specific analyses of the other compounds did not appear warranted. Specific findings and observations from this study are summarized in the sections that follow. They are grouped hi a manner similar to the organization of the report. Data Quality and Data Limitations l. The analytical protocol for 237H-TCDD and developed for this study l?hi found to be :nntisfactory for isomer?specific determinations of 2378-TC00 and in selected pulp and paper mill sample matrices. intro-laboratory method validation experiments for pulp, sludge, and wastewater effluent samples (3 l: 3 indicate the performance of the analytical method with respect to precision and spike recovery is demonstrably uniform. The method performance does not appear to be sensitive to any specific matrix or chemical effects which might be associated with the manufacturing processes at a given mill. Limited inter-laboratory comparisons incorporating different sample preparation, analytical methods, and calibration standards confirmed the presence of 2378-TCDU and selected samples. However. a consistent bias was observed for quantitation of both 2378-11200 and 2. wi?1 few exceptions, the data Quality assurance objectives established for this study for and 2378-TCDE were achieved. Laboratory precision expressed as relative percent differ- ence between duplicate analyses for thirty-five determinations was 15 percent mean (range 1-138 percent): and for thirty?three 2378-TCDF determinations, 16 percent mean (range 0?62 percent). Field precision for eight 2378-TCDD 1determinations was 14 percent mean (range 4-19 percent); and for nine 2378- TCDF determinations. 22 percent mean (range 0-99 For thirty?five 2378-TCDD determinations, accuracy ex- pressed as percent spike recovepy was l6} percent mean (range 66-168 percent); and for thirty?five determinations. 182 percent mean (range 58?153 percent). Including results from intrarlaboratory method validation experiments. 97 percent of the analyses met the quality assurance objectives for laboratory precision and accu- racy. Ninty?five percent of 133 determinations for and for 2373-TCDF resulted in analytical data suitable for project objectives. (8) Target analytical deteCtiom levels of" for solid samples were achieved for all but one sample for 2378-TCDD and all but one sample for (different samples). Target analytical detection ?evels of 6.31 for liquid samples were achieved for alu but three samples for 2378- TCDD and all but two samples for ?lifferent samples). 3. tmss' flow calculations for 2378-TC00 and 2378-TCDF combine analytical results with mass flow rates of solid materials (pulps. sludges) and liquids (Haters, wasteeaters). The mass flow rates for pulps and final treated uastevater effluents are considered to be accurate within less than percent while mass flow rates for sludges, within less than tl? percent to l5 percent. Mass flow rates for internal plant wastewaters were?qenerally based upon best engineering.estimates and are considered accurate to I less than :29 percent to 25 percent. The reliability of reported bleach plant chemical application rates varied considerably from mill to mill, and in two cases were best-engineering eutimates. Hon-detect analyses were treated as zero for mass balance calcula~ tions. The calculations and analyses presented in this report should be viewed accordingly. and PCDP: Found in Pulp and Paper Mill Matrices 1. Analyses of dibenzo-p-dioxins and dibenzofurans from samples obtained at a number of bleached kraft pulp and paper mills processing primarily virgin fiber uniformly show that dioxin (2378-TCDD) and (2378-TCDF) are the principal W003 and found. This is particularly evident when the data are considered in light of USEPA's toxic equivalents approach for dealing with mixtures of and 2. Data for the five mills included in this study show there is a characteristic ratio associated with indi~ vidual bleach lines and individual mills, ranging from about 2 to about 18. This observation suggests that once 1nd are formed, they are not altered in further procesninq or in wastewater treatment. Factors accounting for the differences in ratios across bleach lines and across mills have not been determined, nor has the possible procvns significance been formulated. Sources of and 2378-TCDF l. 2378-TCDD and 2378-TCDP are formed during the bleaching 'of kraft hardwood and softwood pulps with chlorine and chlorine derivatives at mills included in this study. 2. was not detected in seven unbleached kraft pulps collected at the five'mills at detection levels-ranging from 0.3 to LO ppt. was not detected in four of seven unbleached pulps at detection levels less than 0.3 ppt, but was found in three pulps collected at two mills at levels ranging from 1.1 to 2.3 ppt. The positive findings in unbleached pulps may be attributed to reuse of contaminated paper machine white waters for brownstock pulp washing or dilution. 3. 2378-TCDD was found in seven of nine bleached pulps collected at the five mills at concentrations ranging from 3 to 51 and was found hi eigin: of nine bleached pulps .Jt levels ranging from 8 to 336 ppt. The median and mean concentrations are presented below: 237e-rcoo zaia?rcqr Hedian . 50 Mean 13 93 l. 237B-TCDD and 2378-TCDF were found in most untreated bleach line filtrates sampled from the five mills. Hastewatxs from. caustic extraction stages (8 and 30) generally contained the highest concentrations and mass discharges from the bleach lines sampled. S. The distributions 2378-TCDD and 2378-TCDF in bleach line exports (bleached pulp and t?each plant uastevaters) were found to be highly variable from bleach line to bleach line. However, and were partitioned similarly to bleached pulps and bleach plant uastewaters within each bleach line. 6. 2378-TCDD was found in paper machine wastevaters from three of five mills and was found in paper machine wasteuaters from each mill. The levels of 2378-TCDD and 2378-TCDF found in paper machine wastewaters were significantly less than found in the respective bleach plant wastewaters at four of five mills. 7. 2373-TCDD was found in one of five sludge landfill n: runoff samples at 9.025 ppt, while 2378-TCDF was found in of five samples at levels ranging from 9.91 to 9.11 ppt. and were not detected in coal?fired power boiler ash sa?clcs two .at detection levels less than 1.0'ppt. B. 2378-TCDD and other were found in?a sample of blue dye collected during preliminary sampling at one mill at levels of 3.4 and 53 ppt, respectively. Formation of and 2378-TCDP 1. The rates of formation of 237B-TCDD and 237B-TCDF normalized to lbs/ton (kg/kkg) of'air dried brownstock pulp are summarized below: 10"3 lbs/ton (kg/kkg) of Brownstock Pulp Bleach Line Exports Total Hill Exports (eight bleach lines) (five mills) Range Median 4.1(2.0) 3.0(l.5) Mean 8.9(4.0) 4.4(2.2) gave-Tour . Range Median . 12.5(6.3) 19(9.5) "Dan en (34} 41(21) it) .. a? The range computed from -bleach lino' exports exceeds that computed from total mill exports because of the integration of results from mills with multiple bleach lines in the mill export calculations. The extent to yhich these data are representative 0 of long?term operations at the five mills, or are representative of the bleached kraft industry as a whole is not known. 1 - 2. IAlthough the data from this study are limited, the results suggest casual relationships between the formation of andf2378-TCDF and the degree of bleaching across.bleach lines as estimated by the chlorine and chlorine equivalents applied to theiunbleached pulp. and (2) the amount of lignin removed in the pulp and caustic extraction stages as estimated. by the difference in permanganate number (K) and CEK (permanganate number after-caustic extraction). Attempts were made to develop statistical correlatiOns with: the limited data. However, the were generally poor. 3. Bleach lines processing exclusively softwood pulps had higher rates of formation of and 2378-TCDP than bleach lines processing exclusively hardwood pulps. However, bleaching condi? tions on the softwood and hardwood bleach lines were different, and thus, it is not possible to conclude that the general wood species bleached is the (determinant variable in formation of 2373-TCDD and 2378-TCDF. Wastewater Treatment System Findings L- 2318-TCDD was found in treated wastewater effluents from three of five mills at levels ranging from 0.015 to 9.12 and 2378- TCDE was found in four of five effluents at levels from 9.611 to 2.2 ppt. 2. 2378-TCDD was found in wastwater treatment sludges collected from each of the five mills at levels from 17 to 24 (primary sludges), 11 to 719 (secbndary sludges) and 3.3 to 186 (combined sludges). was found at 32 to 380 (primary sludges). 75 to 19960 (secondary sludges) and 34 to 766 (combined sludges). - 3. Hass balance calculations around the wastewater treatment systems for three mills showed that about 50 percent to 86 percent of the 237B-TCDD and 49 perdent,to 68 percent of the 2318-TCDE found in treatment ex orts (treated effluent, wastewater sludge) can be accounted for by treatment system inputs. Eor two mills the treatment system input loadings exceeded the-(export loadings by more than 290 percent. The poor mans balandes are attributed to uncertainties iin sludge, influent, and effluent flow,rates, the sequencing of sampling at certain mills, and, to some extent, analytical variability associated with trace level analyses near method detection limits. I . 4. There is no evidenCe to suggest that*2378-TCDD and 2378-TCDF are destroyed in wastewater treatment systems. Rather, they may'be transferred, to Varying degrees, to wastewater treatment sludges. At two mills, aboUt 10 percent to 15 percent of the 2378-TCDD and 2378-TCDF contained in untreated uastewater streams was tradsferred to the sludges in the wastewater treatment systems, whilegat the remaining three mills more than 38 percent transfer to sludges is indicated. The precise distribution of these compounds hi the effluent between suspended solids and the liquid phase was not determined in this study. 5. The distributions of and 2373-TCDF between wastewater treatment exports (treated effluents and wastewater sludge5)'were highly variable from mill to?mill. However, the partitioning of ZJYB-TCDD and 237B-TCDF between treated effluents and wastewater sludges was consistent within each mill. Hills with higher total suspended solids in effluents had higher levels of and partitioned to theleffluent rather than to the sludge- 1 Pulp and gape: Hill Exports 1. The distributions of and among pulp and paper mill exports (bleached pulp, treated effluents, wastnwater sludges) were highly variable from mill to mill, but the_parti- tioning of and to the exports was consistent within each mill. 2. Mass balance calculations indicate that bleach plant sourdes accounted for about 98 percent to 140 percent of measured in mill exports at three mills, and more than 339 percent at another mill. 2378?11200 was not detected in bleached pulp or bleach plant wastewaters at one mill. For bleach plant sources were found to account for 79 to 136 percent of the amount measured in mill exports at four mills, and more more than 385 percent in the laSt millJ The poor mass balance results at some mills are attributed to uncertainties in mass flow rates Of wastewater, sludge, and pulp, and, to some extent, analytical variability associated with trace level analyses near method detection limits. Chlorinated Phenolics i 1. For this study, chlorinated phenolics include selected chlori- nated phenols, chlorinated gupiacols, and chlorinated voniilins. Chlorinated phenolics were formed hi the bleaching process at each of the five mills. These compounds were not detected in treated intake process waters but were found in bleach plant filtrates and uastowater treatment system influents and effluents. Chlorinated phenolics yore distributed differently at each mill. I 2. Hasteuatera from caustic extraction stage (8 and SO) washers accounted for most of the chlorinated phenolica. This finding in similar to findings for 2378-TCDD and 2378-TCDF in bleach line filtrates. 3. The amounts of chlorinated phenolics found in Chatage and E?stage filtrates were normalized to lbs/ton (kg/kkg) of air- dried brownstock pulp and are summarized below: 10-3 lbs/ton (kg/kkgl of Air?Dried Brownstock Pulp Sum of C-Stage and Sum of Chlorinated E-Stage Filtratcs Phenolics (eight bleach lines) Range 9.3-54 (4.2?24) Mean 35 (17) Median 34 (17) With the lhnited data available, correlations betwnen the presence at cthLinated phenolics and 2378-TCDO mt in wasteuater treatment system influents or effluents were not attempted. Because chlorinated phenolics were analyzed only to: H10 wu'e: an evaluation of total chlorinated phenolics exp rt; (rum bleach plants pulp and wasteuaters) codld not be made. with the limited and incomplete wastewater data available, mass balance calculations between internal bleach plant filtrates and wastewater treatment system hwfluents were not attempted. ASSESSMENT OF THE RISKS ASSOCIATED WITH POTENTIAL EXPOSURE TO DIOXIN THROUGH THE CONSUMPTION OF COFFEE BREWED USING BLEACHED PULP-BASED FILTERS EXECUTIVE SUMMARY In the course or the National Dioxin Study, low concentrations of dioxin (TCDD) were detected in background fish samples from locations with no previously known of dioxin contamination. This led EPA to associate the presence of dioxin in whole fish samples with discharges of pulp and paper mills located upstream. Subsequently, dioxin was measured in several pulp and paper mill wastewater treatment plant sludges. Recently, trace concentrations of dioxin also have been measured in samples of bleached pulp originating from various mills, in bleached paper and in other bleached pulp-based products. Available analytical data indicate that bleaching of kraft pulps with chlorine-based chemicals may result in the formation of TCDD and related furans (TCDP). However, the bleaching process varies, and the means by which TCDD and TCDF are formed are not yet known. Because dioxins and furans may be present, at trace levels, in the bleached pulp found in coffee filters, the question of the level of risk to coffee consumers that is attributable to these trace contaminants has been raised. This report evaluates those risks using scientifically based principles of risk assessment. In summary, it can be -9 concluded that, even using assumptions that likely overstate the risk, consumption of coffee brewed using bleached paper filters does not present a significant health risk, that is, the coffee is safe to drink. This risk assessment has combined information on coffee consumption, coffee making practices, coffee filter composition, potential dioxin migration from coffee filters into the brewed coffee, and the Food and Drug Administration TCDD cancer potency estimate, to calculate the dioxin toxic equivalence (TEQ) concentration in coffee filters associated with a pre-selected incremental lifetime risk level of up to in 1,000,000. The one in one million level was selected to represent a level of risk that is clearly considered de no- .m minimis, insignificant, compared to the risks encountered in daily life. Many of the assumptions in this -risk assessment are conservative, resulting in an overestimation of any potential risk to coffee consumers. These include, but are not limited!to, the duration of 55 Iyears of constant daily coffee consumption: the use of a risk specific dose for a non?threshold eVent rather than a reference dose or mechanistically~based de: the use of the upper 95% confidence limit estimate of the TCDD potency factor; assuming 100% OF brewed coffee uses bleached paper coffee filters: and he) the use Of the higher furan migration estimates when dioxin migration was lower for some filters. In conjunction with this risk assessment, analysis of off?the-shelf samples of fiVe different bleached paper coffee filters found measurable levels of TCDD and TCDF ranging from 2.2 TEQs to 6.6 TEQs. Depending upon the amount of coffee brewed and the weight of the vetted filter, migration was conservatively estimated to range from 65?90 percent. The calculated dioxin TEQs in bleached paper coffee filters, for a risk of between 0 and in 1,000,000, range from 20 TCDD TEQs for average drinker coffee consumptica to 11 TCDD TEQs for heavy drinkers (the 90th percentile). Comparing the consistently law measured levels of TCDD and TCDF in bleached paper coffee filters with the estimated RSLs, it can be concluded that the consumption of bleached paper filter-brewed coffee is below the pre-selected incremental risk level of up to in 1,000 000 and, given the numerous conservative assumptions which have been incorporated into the risk assessment, the risks are close to zero. Using bleached paper coffee filters, therefore, does not present a significant health risk to the coffee consumer. ASSESSMENT OF POTENTIAL HEALTH RISKS TO PULP AND PAPER MILL WORKERS FROM DERMAL EXPOSURE TO DIOXIN IN BLEACHED PULP, PAPER AND PULP-BASED PRODUCTS EXECUTIVE SUMMARY OF PRELIMINARY RESULTS Background Dioxin has been an important issue in environmental aid occupational health for nearly two decades. Most attention has focused on (TCDD) among 75 chlorinated dioxin compounds and 135 closely related chlorinated dibenzofurans. The toxicity of the chlorinated dioxins, their persistence in soil and sediments, the detection of these chemicals at a variety of sites in the United States, and the need for a systematic study to determine the extent of dioxin contamination led the U.S. Environmental Protection Agency (EPA) to deveIOp the National Dioxin study in 1983, which was conducted over the next three years. In the course of the National Dioxin Study, low concentrations of dioxin were detected in background fish samples from locations with no previously known sources of dioxin contamination. This led the EPA to associate the presence of dioxin in whole fish samples with discharges of pulp and paper mills located Upstream. Subsequently, dioxin has been measured in several pulp and paper mill wastewater treatment plant sludges. Recently, trace concentrations of dioxin also have been measured in samples'of bleached pulp originating from various mills, in bleached paper and in bleached pulp-based products. Available analytical data indicate that bleaching of kraft pulps with chlorine may result in the formation of TCDD and (TCDF). However, the bleaching process varies and the means by which TCDD and TCDF are formed is not yet known. The National Council of the Paper Industry for Air and Stream Improvement, Inc. (NCASI) contracted with Envirologic Data, Inc. to assess the potential health risks to pulp and paper mill workers from dermal exposure to dioxin in bleached pulp, paper, and pulp-based products. Risk assessment, as defined by the National Academy of Sciences, is the characterization of the probability of potentially adverse health effects from human exposure to environmental hazards. The risk assessment process is usually divided into four major steps: hazard identification, dose-response assessment. exposure assessment, and risk characterization. In its investigation, Envirologic Data used the guidelines for Carcinogen Risk Assessment as a general framework and guide for conducting the study. ?ggard Identification . Public health concerns relative to dioxin have revolved principally around the substance?s high acute toxicity to some laboratory animals, its ability to cause cancer in some laboratory animals, and its persistence in the environment. while dioxin has been shown to cause cancer in bioassays of laboratory animals, there is insufficient evidence to suggest a direct link between dioxin and cancer in humans. A few epidemiologic studies have been reported to find a relationship between soft?tissue sarcoma in humans and eXposure to substances contaminated with dioxin. However, problems with these studies and the lack of confirming evidence in.a number of similar studies lead to the conclusion that a causal link between dioxin exposure and cancer in humans has not been adequately established. Chloracne (a skin disorder) has been the principal adverse effect observed after exposure to high levels typically following accidents, leaks, explosions, or certain production processes. In fact, chloracne is considered to be the hallmark of human exposure to dioxin. Qgse-Response Assessment In its analysis, Envirologic Data used a non?threshold dose-response model for the mechanism of TCDD-induced carcinogenicity. Based on an in-depth analysis of U.S. federal agency approaches to TCDD dose response, anirologic Data chose the FDA cancer potency and corresponding virtually safe dose (VSD) for use in its analysis. Envirologic Data has concluded that the FDA's VSD is fully protective of public health. Exposure Assessment The physical and chemical properties of TCDD, as well as the behavior of TCDD in soils, suggest that any dioxin in bleached pulp, paper, and pulp-based products is not readily available for human uptake through typical handling and use practices in pulp and paper mills. To estimate absorption of TCDD and its equivalents in bleached pulp, paper, and pulp?based products through the skin of pulp and paper mill workers, an exposure model based on uptake of TCDD in soil Exposure to was conservatively modeled using the highest reasonable estimates of dermal contact. Risk Characterization Numerical results of the risk assessment are expressed as concentrations of TCDD toxic equivalents in bleached pulp, paper, and pulp-based products corresponding to a pre?selected, upper-bound lifetime cancer risk level of one in one million. The one in one million level was selected to represent a level of risk that is clearly considered g2 minimis, insignificant, compared to the risks encountered in daily life. Concentrations of TCDD and its equivalents in bleached pulp, paper, and pulp-based producLu at this risk level (virtually safe concentrations) correspond to the level of exposure provided by the FDA's virtually safe dose. Envirologic Data concludes that the calculated virtually safe concentrations are fully protective of health. The preliminary results indicate that the actual risk fron dermal exposure to these concentrations of TCDD equivalents in the product is less than the one in one million level used in the risk calculationsrare. First, the FDA virtually safe dose used in the analysis is calculated from a 95% upper-confidence-bound cancer potency. ,The non-threshold approach to risk modeling of TCDD taken by the FDA represents a conservative approach in light of evidence that TCDD acts as a cancer promoter rather than as an initiator. In addition, conservative exposure modeling pagameters were used in the analysis to account for plausible worst-case dermal eXposures. The preliminary results show that a virtually safe concentration of 2,000 TCDD equivalents in bleached pulp, paper, and pulp-based products were estimated to correspond to 6 a 1x10- maximum risk level. The virtually safe concentrations of TCDD and its equivalents estimated for the analysis can be compared to the low levels of TCDD and TCDF detected in bleached pulps and consumer products. TCDD was measured in seven of nine bleached pulps sampled as levels ranging from not detected (at a detection limit of 1.0 ppt) to 51 with a median of 4.9 ppt. TCDF was detected in eight of nine bleached pulps at levels ranging from not detected (at a detection limit of 1.2 ppt) to 330 with a median of 50 ppt. (The EPA has assigned a toxicity equivalence factor (TCF) or 0.1 relating the toxicity of TCDF to that of TCDD.) The testing results of three bleached pulp-based products that have been analyzed for TCDD and TCDF are presented in the report. In bond paper, concentrations of TCDD were measured at 13 ppt, and TCDF was measured at 240 and 290 ppt. TCDD was not detected in diaposable diapers (at detection limits of 2.1 and 2.6 ppt): TCDP was measured at 7.2 and 8.8 ppt. TCDD was measured at 3.7 and 3.9 in paper towels, while TCDF was measured at 32 and 33 ppt. The TCDD and TCDF concentrations measured in bleached pulps and consumer preducts appear to be at least an order of magnitude less than the corresponding virtually safe concentration of TCDD equivalents estimated in this analysis. Based on the preliminary results, the presence or low levels of TCDD and its equivalents in bleached paper and bleached pulp-based products does not present a significant risk to pulp and paper mill workers through dermal contact. Given the conservative dose-response and exposure analyses, concentrations of TCDD equivalents in pulp, paper, and pulp-based products could be much higher than the virtually safe concentration of 2000 estimated in the analysis and still result in an insignificant risk to workers' health.