Lcr. Kidd et al., Urinary excretion of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in white, African-American, and Asian-American men in Los Angeles County, CANC EPID B, 8(5), 1999, pp. 439-445
Meats, such as beef, pork, poultry, and fish, cooked at high temperatures p
roduce heterocyclic aromatic amines, which have been implicated indirectly
as etiological agents involved in colorectal and other cancers in humans, T
his study examined the urinary excretion of a mutagenic/carcinogenic hetero
cyclic aromatic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhI
P), among 45 African-American, 42 Asian-American (Chinese or Japanese), and
42 non-Hispanic white male residents of Los Angeles who consumed an unrest
ricted diet, Total PhIP (free and conjugated) was isolated from overnight u
rine collections, purified by immunoaffinity chromatography, and then quant
ified by high-pressure liquid chromatography combined with electrospray ion
ization mass spectrometry, Geometric mean levels of PhIP in Asian-Americans
and African-Americans were approximately 2.8-fold higher than in whites. T
he urinary excretion levels of PhIP were not associated with intake frequen
cies of any cooked meat based on a self-administered dietary questionnaire,
in contrast to our earlier finding (Ji et al,, Cancer Epidemiol, Biomark,
Prev., 3: 407-411, 1994) of a positive and statistically significant associ
ation between bacon intake and the urinary level of 2-amino-3,8-dimethylimi
dazo[4,5-f]quinoxaline (MeIQx) among this same group of study subjects, Alt
hough there is a statistically significant association between urinary leve
ls of PhIP and MeIQx (2-sided P = 0.001), 10 subjects (8%) displayed extrem
e discordance between urinary PhIP and MeIQx levels. Several factors, inclu
ding variable contents of heterocyclic aromatic amines in food, enzymic and
interindividual metabolic differences, and analytical methodology determin
e the degree of concordance between the urinary excretion levels of PhIP an
d MeIQx, Accordingly, urinary excretion levels of a single heterocyclic aro
matic amine can only serve as an approximate measure of another in estimati
ng exposure to these compounds in humans consuming unrestricted diets.