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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