Tobacco Documents Online

Submission by Philip Morris U.S.A. The National Toxicology Program - Appendix 7 - Benzo [a] pYrene: Environmental Distribution and Human Exposure March 20,1998

1- i F i i I I F i i Benzo(alpyrene: Environmental Distribution and Human Exposure Incomplete combustion of organic matter represents the major source of polynuclear aromatic compounds (PAH) in the environment. PAHs are found at detectable concentrations in air, water, and soil samples of all types. Concentrations are typically small, in the order of µg/kg or ng/m3. Since PAHs are highly lipophilic, they accumulate in organic fatty material and therefore have the potential to concentrate in the food chain. Of the numerous PAHs, one compound that has perhaps received the most attention is benzo[a]pyrene (BaP). It is the focus of this discussion. The International Agency for Research on Cancer (IARC) has classified BaP as probably carcinogenic to humans -- IARC Overall Evaluation 2A (IARC, 1983, 1986a, 1986b). BaP has been identified in both mainstream and sidestream smoke from cigarettes, cigars, and pipes; marijuana smoke; and smoke-polluted environments (IARC, 1986b). Non-occupational inhalation exposure to BaP is primarily from tobacco smoke and urban air. However, Hattemer-Frey and Travis (1991) estimate that inhalation accounts for only 2% of the total daily intake of BaP. The focus of this paper therefore concerns the environmental distribution of BaP and human exposure to BaP.

Atmosphere: Emission Sources of BaP r I t Osborne and Crosby (1987) cite the principal sources of BaP in the atmosphere as (1) coal- and oil-fired power stations, (2) domestic heating, (3) miscellaneous industrial processes, (4) vehicle exhausts, and (5) cigarette smoke, forest fires and volcanic activity. The yearly global emission of BaP is estimated to be about 5,000 tons, with the greatest contribution coming from coal combustion., BaP emissions in the U.S. have'been estimated to be 1,260 tons/year, accounting for approximately 25% of the worldwide total((Trimmer, 1979). As can be seen in Table 1, the major emission sources in the U.S. are heating and refuse burning. The percentages in Table 1 are derived from a table presented by Grimmer (1979), reproduced herein as Table 2. Since Osborne and Crosby (1987) cited cigarettes as a principal source of BaP emissions, an estimate was calculated of the tons emitted in sidestream smoke/year. This estimate is based on cigarette consumption/year in the U.S. (Tobacco Manufacturers Association, 1997), and uses the value of 147 ng/cig BaP in sidestream smoke (SS) (based on values for the 1R4F reference cigarette cited in R.J. Reynolds, 1988). Figure 1 shows that for the years 1983-1996, the estimated emission of BaP in sidestream smoke to the atmosphere is less than 0.099 tons/year, which calculates to be less than 0.007% of the total estimated emissions in the U.S: Thus, SS is certainly not a major contributor to BaP in the atmosphere, compared to other sources. -2-

Percentage by source of estimated BaP emission in the United States: Table 1. L r r Emission source Automotive exhaust Heating Refuse burning Industrial plants -7 Percentage 1.7 38 45 16

i I r. I,* Table 2. Estimated B(a)P emissions m ' the ITnited States, af ter Grimmer (1979) Source Tons/year Total Vehicle exhaust Gas-powered cars 10 Gas-powered trucks 12 Diesel fuel-powered trucks and buses 0.4 22.4 Heating Coal Hand-stoked residential furnaces 420 Intermediate units 10 Coal-fired steam power plants 1 Oil Low-pressure air atomizer and others 2 Gas 2 Wood 40 475 Refuse burning Commercial, residential, institutional and apartments 33 Open burning Forest and agricultural 140 Vehicle disposal 50 Coal refuse fires 340 563 Industrial plants Petroleum cracking 6 Asphalt air-blowing <1 Coke production 192 200 Total (all sources) 1260

r F r I I I 1 I Ii f . Figure 1. ESTIMATED BaP EMITTED INTO ATMOSPHERE FROM SIDESTREAM SMOKE i

L Occurrence of BaP in Air The concentration of BaP in ambient air is dependent on a number of factors: 1) Season -- generally highest in winter and lowest in summer; 2) Source of emission -= industrial and transportation; . 3) Meteorologicalfactors; 4) Urban vs. rural settings; and 5) Geographic location (Europe vs. U.S.). r F i Table 3 and Table 4 (after Pucknat, 1981) illustrates some of these factors; they are cited in the literature as being used for various calculations. The U.S. average for urban sites for the 5-year period 1966-1970 is about 2.0 ng/m3 (Pucknat 1981, p. 85). The BaP concentration range in urban air of U.S. cities as determined by various authors in recent years (published during the period 1971-1977) is 0.13 to 3.2 ng/m3 (Pucknat, 1981, p. -169). As can be seen in Table 5, BaP levels in European countries have historically been much higher than those reported in the U.S.; there is also a wide variation from winter to summer. Pucknat (1981) cites a paper within a paper which reports a "safe" lifetime BaP dose for human lungs as 4.3 mg. On the basis of this value, he then states that the concentration of atmospheric BaP should not exceed 120 ng/m3. A standard BaP concentration for industrial workers was determined to be 200 ng/m3. (OSHA Workplace Exposure Limit (PEL) for coal tar pitch -3

Table 3. Average BaP concentrations -(ng/m3) in U.S. urban and rural areas (after Pucknat (1981), Table 5.14, p. 168). i Ii I I I I L F 1966 1970 1976 Urban 3.2 2.1 0.5 Rural 0.4 0.2 0.1

t i I I Table 4. Summer-winter average of ambient BaP concentrations (ng/m3) in the air of selected cities (after Pucknat (1981), p. 169). Clty BaP (ng/m) Atlanta 4.5 Birmingham 15.7 Detroit 18.5 Los Angeles 2.9 Nashville 13.2 New Orleans 3.1 San Francisco 1.3

r i r I i I I I Ii Table 5. Atmospheric benzo[alpyrene concentrations (ng/m3) for various l®cations around the world in summer and winter (after Osborne and Crosby (1987), Table 17.1, page 302). Location Winter Summer Year Sydney 8 0.8 1962-63 Liege, Belgium 110 15 1958-62 Ontario, Canada 15-20 1.2-18.5 1961-62 Prague 122 19 1964 Copenhagen 17 - 5 1956 Helsinki 5 22 1962-63 Paris 300-500 1958 Budapest 1000 32 1968 Teheran 6 0.6 1971 Belfast 51 9 1961-62 Milan 610 3 1958-60 Amsterdam 22 2 1968 18 2 1969. 5 . 1970 8 1971 Oslo ` 15 1 1956 Poland 130 30 1966-67 Madrid 120 0 1969-70 Stockholm 10 1 1960

r i L IT I I volatiles of 0.2 mg/m3 averaged over an 8-hour workshift (Final Rule, January 1989); NIOSH recommended airborne exposure limit. for coal tar pitch volatiles of 0.1 mg/m3 over a 10-hour workshift; ACGIH recommendation that worker exposures, by all routes, be controlled to levels as low as can be reasonably achieved; New Jersey Hazardous Substance Fact Sheet -- Benzo(a)Pyrene -- Micromedex, Inc., 1974-1998.) Water: Sources and Occurrences According to a National Academy of Sciences (NAS) report (Petroleum in the Marine Environment, NAS 1975), about 6 million tons of petroleum hydrocarbons enter the oceans annually; the major contributors are marine transportation and runoff (urban and river). Other sources of PAHs in the oceans are coastal refineries, industrial and domestic waste, natural seeps, and atmospheric fallout. BaP levels found in water are shown in Table 6 (after Osborne and Crosby, Table 17.5, p. 307). These.particles will fall slowly to the bottom, and thus PAH compounds are removed from solution. -Tlie levels of BaP reported in sediments on the other hand can be rather high in the order of ug/kg or even mg/kg of dry sample. As one can see, the levels vary significantlyy depending upon the sampling location and the type of water, but in general they are rather low. This is not unexpected since PAH compounds in solution are readily adsorbed on to the surface of dust, soil or other insoluble particles. -4-

I-' L F I I 1*. Table 6. BaP levels in water. Sample Country BaP (ng/L) Tap water FRG 0.25 - 9 Tap water USA 0.2 - 1.6 Groundwater FRG 1 - 10 Groundwater USA 0.2 Rainwater FRG 4 - 80 Reservoirs UK 0.7 - 3.8 Wellwater UK 0.2-0.6 Well water FRG 2- 15 Lake.Erie USA 0.3 River Rhine at Mainz FRG 50 - 110 River Rhine at Koblenz FRG 10 - 60 River Thames UK 170 - 280 River Thames UK 4.2 - 430 River Trent UK 5.3 - 504 River Severn UK 1.5 - 48 Ohio River USA 5.6 Delaware River USA 41.1 Motorway run-off UK 570 Domestic effluent FRG 38 Human urine 1300 Sewage sludge FRG 1.7 (mg/kg)

Soil: Sources and Occurrences L The majority of investigations of PAHs in soils have been carried out by Soviet i r i I investigators between 1967-1977; these papers only reported the BaP content (Osborne and Crosby, 1987). The concentrations of BaP measured in the U.S.S.R. ranged from 0.0008 mg/kg to 200 mg/kg, with the maximum value found in the vicinity, of an oil refinery. Similarly high concentrations (650 mg/kg) were measured in the area of a carbon black factory. In samples of sandy and forest soil collected in West Germany, considerably lower concentrations of BaP, ranging from 0.001 to 0.0004 mg/kg, were found. The contamination of soil can be attributed almost exclusively to emissions from combustion processes. In the majority of surface soil samples taken in Iceland, where hardly any fossil fuels are burnt, the most commonly found PAHs were not detected (detection limit for BaP, e.g., 0.02,ug/kg soil). Soil samples taken at the Reykjavik, Iceland airport, however, were extremely contaminated, with BaP concentrations reaching 0.785 mg/kg. "Human Exposure to Benzo(a)pyrene" Hattemer-Frey and Travis (1991) used a multimedia transport model to evaluate environmental partitioning of BaP. Measured and predicted environmental concentrations were used to estimate the accumulation of BaP in the food chain and the subsequent extent of human exposure from inhalation and ingestion. Their results showed that the food chain is the dominant pathway of human exposure, accounting for about 97% of the total daily intake of BaP. See Table 7.

F Table 7. Pathways of human exposure to B(a)P (after IIattemer-Frey and Travis, 1991). Source Dailv intake (E.ccg/day) % of total daily intake Food (total) 2.1 97 Inhalation 0.05 2 Water 0.01 1 TOTAL 2.16 100 F I I I I I Ii

i I-- This value of approximately 2.2,ug/day average daily intake of BaP is in agreement with other values reported in the literature (e.g., Suess,1976). Hattemer-Frey and Travis (1991) then went on to discuss human exposure to BaP from smoking and indoor air pollution, referencing a paper by Butler and Crossley (1979) that reportedly estimated that one cigarette delivers approximately 39 ng of BaP. Further, Hattemer-Frey and Travis used in their calculations an estimate that the average smoker smokes 20 cigarettes per day. Based on these calculations, they suggested that the smoker receives an additional 780 ng/day (0.78 ,ug/day) BaP from smoking. Additionally, they again referenced Butler and Crossley (1979), who reported that concentrations of BaP measured indoors (2.2 ng/m3) were comparable to outdoor air concentrations (2.5 ng/m3); thus, indoor activities would not substantially.increase the BaP intake, since inhalation is not a major pathway of human exposure to BaP. Mainstream smoke concentrations of 9.2 ng BaP/cigarette have been reported for the Kentucky Reference Cigarette 1R4F (R.J. Reynolds, 1988). The value for a filtered cigarette could be rounded to 10 ng BaP/cigarette. Thus, an average (1 pack/day) smoker of filtered cigarettes would be exposed to an additional 0.2 ,ug/day of BaP, a level which is approximately 4 times the estimated daily intake of BaP by inhalation. [See Table 8] However, one should keep in mind that more than 90% of the daily intake of BaP is derived from other sources, primarily food. r This can be examined from the perspective of the daily lung burden as described by O O\ . O Chen and Thilly (1996). Instead of using the value of 10 m3/day for breathing, the more widely used ~ W value of 20 m3/day will be chosen. The value of 2.5 ng BaP/m3 as the "urban air concentration" will ~ ~ -6-

Table 8. Estimated exposure of a smoker to BaP (ng/day). Cigarettes/day 10 20 40 1R4F filtered cigarette 100 200 400 I' F

be used, which, as shown in Table 9, is probably an over-estimation of the urban air BaP I concentration in the 1990s, if the downward trend has continued. Using the formula (breathing rate/day X urban air BaP level) = ng BaP by inhalation/day, for a breathing rate of 20 m3/day X 2.5 ng BaP/m3 = 50 ng BaP/day or 0.05 gg/day by inhalation/day. The level of 0.05 ug/day by inhalation corresponds to what Hattemer-Frey and Travis reported [See Table 71. Examining BaP Exposure from ETS or Room-Aged Sidestream Smoke (RASS) Attributing levels of PAH (BaP) in the air of restaurants, public rooms, etc., to ETS is difficult since other sources may be present, and other factors, such as ventilation rates, number of smokers, etc., may confound the issue. However, Grimmer (1983), under controlled conditions, reported 22 ng/m3 BaP where cigarettes were being smoked and less than 3 ng/m 3 where no cigarettes were being smoked. He calculated that ETS contributed about 7 times the background BaP level. Grimmer states that "the measured concentrations of 22 ng BaP per cubic meter has to be considered as a maximum BaP concentration attainable by smoking. In practice nobody would tolerate this concentration" of smoke due to eye irritation, etc. ' A 12-month inhalation study in rats using room-aged sidestream smoke (RASS) (INBIFO, data enclosed) reports the following concentrations of BaP in RASS from 1R4F cigarettes: 0.13 ,ug/m3 (upper limit) for the whole-body 12-month exposure group, and 0.121 gg/m3 (upper -7-

L I ( F F I Table 9. Average BaP concentrations (ng/m3) in U.S. urban and rural areas during 1966-1977 (after Pucknat 1981, Table 5.14, p. 168). Location Year 1966 1970 1976 Urban 3.2 2.1 0.5 Rural 0.4 0.2 0.1

limit) for the head-only 12-month exposure group (Haussmann et al., 1998). Again, if we consider urban ambient air to contain an average of 2.5 ng/m3 BaP, one can see that the rats in this study were exposed to approximately 50 times the level of BaP found in ambient air. The RASS concentrations in this study were approximately 100-fold higher than the maximum of the average concentrations of respiratory suspended particles (RSP) reportedly attributable to ETS (Guerin et al., 1992; U.S. EPA, 1992; Jenkins et al:, 1996). Thus, if one assumes that BaP, which is in the particulate phase, tracks with RSP, then 0.13 µg/m3 would correspond to 0.0013 ~zg/m3. From the perspective of human exposure, this level of exposure would be equivalent to 0.0013 ,ug/m' X 20 m3/day = 0.026 gg/ or 26 ng/day, which is about half the daily level by inhalation estimated by Hattemer-Frey and Travis. i I I -8-

References r F r i L I F i i Butler, J.D., and Crossley, P., An appraisal of the relative airborne sub-urban concentrations of polycyclic aromatic hydrocarbons monitored indoors and outdoors, The Science of the Total Environment 11: 53-58 (1979). , Chen, J., and Thilly, W.G., Mutational spectra vary with exposure conditions: benzo[a]pyrene in human cells. Mutation Research 357: 209-217 (1996). Grimmer, G.,' Chapter 3--. Sources and occurrence of polycyclic aromatic hydrocarbons. In: IARC Environmental Carcinogens, Selected Methods ofAnalysis, Vol. 3--Analysis of Polycyclic Aromatic Hydrocarbons in Environmental Samples. H. Egan (Ed.). IARC, Lyon, pp. 31-54 (1979). Grimmer, G., and Pott, F. Occurrence of PAH. In: Environmental Carcinogens: Polycyclic Aromatic Hydrocarbons. G. Grimmer (Ed.). CRC Press, Inc., Boca Raton, FL, p. 61-128 (1983). Guerin, M.R., Jenkins, R.A., and Tomkins, R.A. The Chemistry of Environmental Tobacco Smoke: Composition and Measurement. Center for Indoor Air Research, Lewis Publishers, Chelsea, MI (1992) Hattemer-Frey, H.A., and Travis, C.C., Benzo-a-Pyrene: Environmental Partitioning and Human Exposure, Toxicology and Industrial Health 7(2): 141-157 (1991). Haussmann, H.J, et al., Comparison of fresh and room-aged cigarette sidestrearn smoke in a subchionic inhalation study on rats. Toxicological Sciences 41: 100-116 (1998). International Agency for Research on Cancer (IARC), IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Polynuclear Aromatic Hydrocarbon Compounds, Part 1, Chemical, Environmental and Experimental Data. IARC, Lyon, Vol. 32, pp. 211-224; pp. 36-37 (1983). International Agency for Research on Cancer (IA.RC), IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Biological Data Relevant in the Evaluation of. Carcinogenic Risk to Humans. Tobacco Smoking. IARC, Lyon, Vol. 38, pp. 3 89-394 (1986a). International Agency for Research on Cancer (IARC), L4RC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Biological Data Relevant in the Evaluation of Carcinogenic Risk to Humans. Tobacco Smoking. IARC, Lyon, Vol 38., pp. 101-102 (1986b). Jenkins, R.A., et al., Exposure to tobacco smoke in sixteen cities in the United States as determined by personal breathing zone air sampling. JExpos Analysis Environ Epidemiol 6: 473-502 (1996). -9-

National Academy of Sciences (NAS), Petroleum in the Marine Environment, Washington, D.C., National Academy of Sciences (1975). r I Osborne, M.R., and Crosby, N.T., Occurrence of benzopyrenes in the environment. In: Benzopyrenes. Cambridge University Press, Cambridge, pp. 301-316 (1987). Pucknat, A.W., Health Impact of Polynuclear Aromatic Hydrocarbons. Noyes Data Corp., Park Ridge (1981). R.J. Reynolds Tobacco Company, Chemical and Biological Studies on New Cigarette Prototvpes that Heat Instead of Burn Tobacco, R.J. Reynolds Tobacco Company, Winston-Salem, North Carolina, pp.119-180 (1988). Suess, M.J., The environmental load and cycle of polycylic aromatic hydrocarbons. Sci. Total. Environ. 6: 239-250 (1976). Tobacco Merchants Association of the United States, Inc., Vol. 1, Tobacco USA (Table la), Princeton, N.J. (Revised October 1997). U.S. Environmental Protection Agency, Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders. US EPA/600/6-90/006 F (1992). -10-