Mutagenicity and aromatic amine content of fumes from heated cooking oils produced in Taiwan
Introduction
Several aromatic amines have been implicated as human bladder carcinogens, including 2-naphthyl-amine (2-NA) (Schulte et al., 1986), 4-aminobiphenyl (4-ABP) (Hueper, 1969), benzidine (Meigs et al., 1986), 4,4′-methylenedianiline (Schulte et al., 1987), 4,4′-methylenebis (2-chloroaniline) (Ward et al., 1988), o-toluidine (Rubino et al., 1982) and 4-chloro-o-toluidine (Stasik, 1988). According to earlier studies, 2-NA and 4-ABP are considered particularly important as aetiological agents inducing human bladder cancer associated with cigarette smoking (Gorrod and Manson, 1986) and occupational exposure (Riffelmann et al., 1995).
Numerous studies have indicated that smokers exhibit higher haemoglobin adducts of aromatic amines than non-smokers (Bryant et al., 1988; Vineis et al., 1990; Weston et al., 1991). The level of adducts in non-smokers is positively associated with their exposure to environmental tobacco smoke (Maclure et al., 1989). Roughly 50% of attributed risk for bladder cancer is associated with cigarette smoking, which seems to indicate that there remains some exposure to aromatic amines that is not associated with tobacco smoke.
Early Western investigations (Gere, 1982; Teschke et al., 1989) indicated that air samples from restaurant kitchens were mutagenic in Salmonella typhimurium strains TA98 and TA100, as were fumes arising from cooking certain foods (Lofroth et al., 1991; Rappaport et al., 1979). Recently, according to research from mainland China and Taiwan, polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (B[a]P), dibenz[ah]anthracene (D[ah]A) and benz[a]anthracene (B[a]A) were extracted from rapeseed, sunflower, vegetable, and refined-lard oils (Chiang et al., 1997; Li et al., 1994). Several PAHs are considered to be aetiological agents for lung adenocarcinoma among Chinese women. In our previous studies, some mutagens were not identified and confirmed by comparing with the amounts of mutagenicity between cooking oil fumes and identified PAHs (Chiang et al., 1997, Chiang et al., 1998; Wu et al., 1998a). Epidemiological studies have observed an elevated incidence of cancers among non-smoking women with long-term exposure to cooking oil fumes (Gallagner and Elwood, 1964; King and Haenszel, 1973), and excess bladder cancer was reported among cooks who had occupational exposure to cooking oil fumes daily (Schoenberg et al., 1984). The aromatic amines were suspected aetiological factors for contracting bladder cancer among these people. There are limited data about the arylamine content of fumes from cooking oils. We analysed the mutagenicity of the frequently used oils (sunflower, vegetable and refined-lard oils) during the past 10 yr in Taiwan. Five aromatic amines, 2-NA, 4-ABP, benzidine, o-toluidine and 4,4′-methylenebis (2-chloroaniline), were analysed. In addition, catechin (CAT) was added to cooking oils before heating to clarify the effect of this antioxidant on mutagenicity and aryl-amine concentrations of fumes produced by the heated cooking oils.
Section snippets
Chemicals
Three commercial hand-made cooking oils (sunflower oil, vegetable oil and refined-lard oil) were purchased at traditional Taiwanese markets. The acetone extracts of the oils and air samples before heating were checked for mutagenicity in order to confirm that the process of cooking was responsible for the mutagenicity of these oils. Each oil (0.1 litre) was poured into an iron pot and heated by an electronic heater at 300±10°C. In addition, we designed another experiment to clarify the effects
Results
The amount of fume particulates and acetone extracts was higher (but not significant) in vegetable oil (Table 1). The acetone extracts of the oils and air samples before heating showed no mutagenicity using the Salmonella mutation assay with tester strain TA98. The fume extracts of sunflower oil and vegetable oil displayed direct (−S-9) mutagenicity when the concentration was greater than 0.5 and 2.0 mg/plate, respectively (Table 2). Extracts from sunflower, vegetable and refined-lard oil fumes
Discussion
In earlier studies, several PAH mutagens [DB[ah]A, B[a]P in mainland China (Li et al., 1994), and DB[ah]A, B[a]P, B[a]A in Taiwan (Chiang et al., 1997)] and volatile organic compounds (Shields et al., 1995) were found in cooking oils. We analysed frequently used oils (sunflower, vegetable and refined-lard oils) in Taiwan and successfully identified two aromatic amines (2-NA and 4-ABP) from these oil fumes. Numerous studies have been conducted which indicate that exposures to aromatic amines
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