Chapter 22
Polycyclic Aromatic Hydrocarbon—DNA Adduct Load in Peripheral Blood Cells Contribution of Multiple Exposure Sources 1
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P. T. Strickland , N. Rothman , M . E. Baser , and M . C. Poirier 1
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Department of Environmental Health Sciences and Department of Epidemiology, School of Public Health, Johns Hopkins University, Baltimore, MD 21205 Laboratory of Cellular Carcinogenesis and Tumor Promotion, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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Polycyclic aromatic hydrocarbons (PAH) are produced by combustion of organic materials, and humans are exposed to these compounds from a variety of sources. In a recent cross-sectional study of PAH exposure in residential fire fighters and controls, PAH-DNA adducts in peripheral nucleated blood cells were examined by immunoassay (ELISA) as potential markers of exposure. Mean adduct levels in caucasian participants (22 detectable/66 tested) increased with exposure to one or more sources of PAH: fire fighting, smoking, and/or char-broiled (CB) food consumption. The effect of dietary PAH on PAH-DNA adduct levels was further investigated in a controlled exposure study in which 4 volunteers consumed CB beef daily for 7 days. PAH-DNA adduct levels increased 3-fold and 6-fold above baseline levels and in two individuals and remained unchanged in two individuals during the feeding period. These results suggest that multiple sources of PAH contribute to the PAH-DNA adduct load in peripheral blood cells and confirm the importance of dietary contributions. Polycyclic aromatic hydrocarbons (PAH) are introduced into the environment by a number of combustion processes, including heat and power generation, coke production, open refuse burning and motor vehicle emissions (.1,2). Individuals can be exposed to PAHs from these environmental sources or from their occupation, diet or smoking habits. In a recent study of exposure to combustion products in residential fire fighters (3,A), we measured several markers of genotoxic damage in nucleated blood cells as potential markers of exposure including sister chromatid exchanges and PAH-DNA adducts. The results suggest a contribution of occupation (fire fighting), diet (char-broiled (CB) food consumption) and cigarette smoking to individual levels of PAH-DNA adducts. In this report, we summarize these findings and present further evidence that dietary PAH contribute to PAH-DNA adduct levels in peripheral blood cells. 0097-6156/91/0451-0257$06.00/0 © 1991 American Chemical Society Vanderlaan et al.; Immunoassays or Trace Chemical Analysis ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
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IMMUNOASSAYS FOR TRACE CHEMICAL ANALYSIS
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M u l t i p l e PAH Exposure
i n Fire
Fighters
B l o o d samples (40 m i s ) were c o l l e c t e d from 43 u r b a n f i r e f i g h t e r s and 38 c o n t r o l s w i t h s i m i l a r demographics and smoking h a b i t s . A d e t a i l e d q u e s t i o n n a i r e was a d m i n i s t e r e d t o p a r t i c i p a n t s t o o b t a i n i n f o r m a t i o n on r e c e n t f i r e f i g h t i n g a c t i v i t y , t o b a c c o smoking ( o r chewing), f r e q u e n c y o f consumption o f CB f o o d and a l c o h o l , and o t h e r p o t e n t i a l c o n f o u n d i n g f a c t o r s ( 3 ) . DNA was e x t r a c t e d from the n u c l e a t e d b l o o d c e l l f r a c t i o n ( b u f f y c o a t ) and a n a l y z e d f o r PAH-DNA c o n t e n t by ELISA as p r e v i o u s l y d e s c r i b e d (5,6) u s i n g a BPDE-DNA s t a n d a r d m o d i f i e d i n t h e same range as t h e b i o l o g i c a l samples (4.4 fmoles/ug DNA). The ELISA employed r a b b i t anti-BPDEDNA ( a n t i b o d y 33, d i l u t e d 1:70,000), g o a t - a n t i - r a b b i t IgG c o n j u g a t e d t o a l k a l i n e phosphatase ( d i l u t e d 1:400) and p - n i t r o p h e n y l - p h o s p h a t e as d e s c r i b e d p r e v i o u s l y (6). Since the antiserum i s c a p a b l e o f r e c o g n i z i n g s e v e r a l PAH-DNA a d d u c t s (_7)> t h e r e s u l t s are e x p r e s s e d as BPDE-DNA a n t i g e n i c i t y and r e p r e s e n t PAH-DNA a d d u c t f o r m a t i o n (.7» 8 ) . The lower l i m i t o f s e n s i t i v i t y o f t h e a s s a y was 0.3 f m o l adduct/ug DNA a t 20% i n h i b i t i o n . PAH-DNA a d d u c t s were d e t e c t a b l e (> 0.3 fmole adduct/ug DNA) i n 35% (28/81) o f t h e i n d i v i d u a l s t e s t e d . Smoking i n c r e a s e d t h e u n a d j u s t e d r i s k f o r d e t e c t a b l e PAH-DNA a d d u c t s (odds r a t i o = 2.4; 95% c o n f i d e n c e i n t e r v a l = 0.96-6.26) ( 3 ) . C a u c a s i a n f i r e f i g h t e r s (66/81) e x h i b i t e d a h i g h e r r i s k f o r t h e p r e s e n c e o f d e t e c t a b l e PAH-DNA a d d u c t s t h a n C a u c a s i a n c o n t r o l s a f t e r a d j u s t m e n t f o r CB f o o d consumption (odds r a t i o = 3.4; 95% c o n f i d e n c e i n t e r v a l = 1.110.5; ρ = 0.04) ( 3 ) . Simple l i n e a r r e g r e s s i o n a n a l y s i s i n d i c a t e d t h a t consumption o f CB f o o d s >3 t i m e s p e r month was a s s o c i a t e d w i t h i n c r e a s e d PAH-DNA adduct l e v e l s (p = 0.04). Thus, t h e t h r e e s o u r c e s o f exposure t h a t c o n t r i b u t e d t o PAH-DNA adduct l e v e l s i n the C a u c a s i a n p a r t i c i p a n t s were f i r e f i g h t i n g , t o b a c c o smoking, and CB f o o d consumption ( F i g u r e 1, 2 and R e f s 3,4). The p e r c e n t a g e of i n d i v i d u a l s w i t h d e t e c t a b l e a d d u c t s i n c r e a s e d w i t h t h e number o f exposure s o u r c e s ( T a b l e I ) , b u t X a n a l y s i s f o r t r e n d was n o t significant. 2
Table I .
Number o f Exposure Sources (FF,SM,CBF) 0 1 2 3
Percent I n d i v i d u a l s With D e t e c t a b l e Levels of PAH-DNA Adducts
Number o f Individuals (n) 10 24 25 7 66
Number w i t h / w i t h o u t D e t e c t a b l e PAH--DNA A d d u c t s without with (0.3 fmole/ug) 8 2 (20%) 16 8 (33%) 16 9 (36%) 4 3 (43%) 44 22
A n a l y s i s f o r Trend: ( c u t o f f a t > 0.3 fmole/ug DNA) X = 0.99 ρ = 0.32 ( c u t o f f a t > 0.75 fmole/ug DNA) X = 2.68 ρ = 0.10 (Reproduced w i t h p e r m i s s i o n from R e f 4. C o p y r i g h t 1990, O x f o r d University). 2
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Vanderlaan et al.; Immunoassays or Trace Chemical Analysis ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
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