- Email: [email protected]
Identification of Carcinogens in Cooking Oil Fumes
Environmental Research Section A 81, 18}22 (1999) Article ID enrs.1998.3876, available online at http://www.idealibrary.com on
Identification of Carcinogens in Cooking Oil Fumes Tai-An Chiang,* 1 Pei-Fen Wu,- ? and Ying-Chin Ko? *Department of Medical Technology, China Junior College of Medical Technology, No. 1, 54 Lane, Wen-Hwa Road, Jen-Te, Tainan, Taiwan; -Department of Industrial Safety and Hygiene, Ta-Jen Junior College of Pharmacy, Pingtung, Taiwan; and ?Graduate Institute of Medicine, Kaohsiung Medical College, Kaohsiung, Taiwan Received December 29, 1997
women in Western and Southeastern countries (King and Haenszel, 1973; McCredie and Coutes, 1989; Koo et al., 1985; Menon and Saw, 1979; Maclennan et al., 1977; Gao et al., 1987). These women smoke little but contract lung cancer rather frequently. Early pathological investigation (Law et al., 1976) showed that Chinese women tend to contract adenocarcinoma, rather than squamous cell carcinoma, implying that the cause of lung cancer in these women may not be smoking. Epidemiological surveys indicated that indoor air contamination deriving from cooking practices might be a important risk factor for lung cancer in Chinese women (Gao et al., 1988; Wu-Williams et al., 1990). Ko et al. (1997) found an 8.3-fold excess risk to contract lung cancer among nonsmoking women exposed to fumes from various cooking oils used for preparing Chinese food without a fume extractor. Experimental studies (Gere, 1982; Teschke et al., 1989) indicate that air samples from restaurant kitchens were mutagenic. Recently, researchers in the People’s Republic of China found that vapors from rapeseed oils were mutagenic (Li et al., 1994; Qu et al., 1992; Shields et al., 1995). According to our previous study, dose-related genotoxicity [sister chromatid exchange (SCE) and SOS] was found for the fumes of several cooking oils (Wu et al., 1998). The mutagenicity of cooking oil exposures was signi7cantly reduced by several methods of fume extraction (Chiang et al., 1998). However, the mutagenic polycyclic aromatic hydrocarbons (PAHs) in fumes from cooking oils, and the variation in carcinogenic contents of cooking oil fumes after fume extraction were not characterized. The purpose of this study was to investigate the PAH content in fumes from six cooking oils, frequently used by Taiwanese women, and to evaluate the ef7cacy of tabletop fume extractors in reducing the toxicity of fumes from these cooking oils.
According to earlier studies, fumes from cooking oils were found to be genotoxic in several shortterm tests such as the Ames test, sister chromatid exchange, and SOS chromotest. Fume samples from six different commercial cooking oils (safBower, olive, coconut, mustard, vegetable, and corn) frequently used in Taiwan were collected. Polycyclic aromatic hydrocarbons (PAHs) were extracted from the air samples and identiAed by high-performance liquid chromatography and conArmed by gas chromatography/mass spectrometry. Extracts of fumes from safBower oil, vegetable oil, and corn oil contained benzo[a]pyrene (BaP), dibenz[a, h]anthracene (DBahA), benzo[b]Buoranthene (BbFA), and benzo[a]anthracene (BaA). Concentrations of BaP, DbahA, BbFA, and BaA were 2.1, 2.8, 1.8, and 2.5 lg/m3 in fumes from safBower oil; 2.7, 3.2, 2.6, and 2.1 lg/m3 in vegetable oil; and 2.6, 2.4, 2.0, and 1.9 lg/m3 in corn oil, respectively. The authors constructed models to study the efAcacy of table-edged fume extractors used commonly by Taiwanese restaurants. Concentrations of BaP were signiAcantly decreased when the fume extractor was working (P:0.05) and the average reduction in percentage was 75%. The other identiAed PAHs were undetected. These results indicated that exposure to cooking oil fumes could possibly increase exposure to PAHs, which may be linked to an increased risk of lung cancer. The potential carcinogenic exposure could be reduced by placing table-edged fume extractors near cooking pots. 1999 Academic Press Key Words: carcinogens; cooking oil fumes; fume extractor.
INTRODUCTION
There is a high incidence of lung cancer in Taiwanese women (Tang et al., 1984) and Chinese To whom correspondence should be addressed. Fax: 886-62605598. E-mail: [email protected]. 18 0013-9351/99 $30.00 Copyright 1999 by Academic Press All rights of reproduction in any form reserved.
19
CARCINOGENIC CONTENTS OF COOKING OIL FUMES
MATERIALS AND METHODS
Sampling Six commercial cooking oils (saf8ower, olive, coconut, mustard, vegetable, and corn) were purchased at a traditional Taiwanese market. These oils were certi7ed by the system of Good Manufacturing Practice (GMP) designed by the Taiwan government (Economic Department Food Good Manufacturing Practice Promotion Organization). Each oil (200 ml) was poured into a 8-cm-diameter iron pot and heated to 250$10@C. Particulates arising from the heated oil samples were collected for 30 min on 37-mm Grade AA glass 7ber 7lter paper by means of a personal sampling pump (8ow rate, 2 liters/min) placed 50 cm above the fuming surface. Another experiment was performed in the presence of a fume extractor. The tabletop fume extractor had a volume 8ow rate of 250 liters/s and was placed 15 cm away from the cooking pot. Each experiment was performed in triplicate.
TABLE 1 Comparison of the Amounts of Fume Particulates from Various Cooking Oils Heated at 250$10@C for 30 min
Cooking oil Saf8ower Olive Coconut Mustard Vegetable Corn
Fume particulate (mg/m3)
Acetone extract (mg/m3 )
24.2$1.3 20.3$0.8 20.8$1.1 21.5$0.9 23.8$1.1 22.4$1.2
21.8$1.2 17.6$1.1 17.1$1.3 18.4$1.1 21.1$1.4 20.2$1.1
wavelength of 306/398 nm. Gas chromatography/ mass spectrometry (GC/MS) was conducted using a HP 5890 Series II instrument equipped with split/ splitless injector and a PTE 5 Supelco 30 cm; 0.25 mm column (0.2 lm). An HP-MSD 5972 mass detector was used as detector and an HP-chemstation-MS as integrator.
Extraction
Statistical Analysis
The 7lter paper was weighed before and after sampling. Each 7lter paper was divided into 1-cm squares with a paper cutter and the pieces were extracted with 100-ml acetone in a shaker. The organic extract was 7ltered through Whatman No. 2 7lter paper, concentrated to about 10 ml in a rotating evaporator at 40@C, and evaporated to dryness under nitrogen. The solid residue was weighed, redissolved in acetone, and stored at !80@C until HPLC analyses were undertaken.
Statistical evaluations were performed using analysis of variance; P:0.05 was considered signi7cant.
PAHs Analysis by HPLC and GC/MS Extracts of samples were passed through a Sephadex LH-20 column (15 mm i.d.;190 mm) at a 8ow rate of 1.5 ml/min, with 2-propanol as eluant. Fractions were collected by a fraction collector at 2-min intervals. An aliquot (10 ll) of each fraction was evaporated and the residue was dissolved in 0.1 ml DMSO for determination of 16 PAHS by HPLC. The fractions were injected into a Supelco LC-PAH column and eluted at a 8ow rate of 2 ml/min, with a linear gradient of 50}100% acetonitrile in water, for 14 min, and held at 100% acetonitrile for an additional 20 min. The resultant peaks were compared with standard calibration curves and deconvoluted by the program in HP Chem Station (Hewlett Packard Co.) Peak areas were used to calculate the concentration of PAHs. The PAHs were monitored by 8uorescence at a
RESULTS
The recovery rates of PAHs analysis by HPLC ranged from 91 to 97%. PAHs were undetectable before the cooking oils were heated. The highest mass of fume particulate was obtained from saf8ower oil, followed by vegetable oil, corn oil, mustard oil, coconut oil, and olive oil (Table 1). Saf8ower oil also yielded the highest amount of solute in the acetone extract. Extracts of fumes from saf8ower oil, vegetable oil, and corn oil contained BaP, DBahA, BbFA, and BaA (Table 2). Concentrations of BaP, DBahA, BbFA, and BaA were 22.7$1.5, 2.8$0.2,
TABLE 2 The Carcinogenic Contents (lg/m3 ) of Fumes from Various Oils Heated to 250$10@C for 30 min Cooking oil Carcinogens
Saf8ower
Vegetable
Corn
BaP DBahA BbFA BaA
22.7$1.5 2.8$0.2 1.8$0.3 2.5$0.1
21.6$1.3 3.2$0.1 2.6$0.2 2.1$0.4
18.7$0.9 2.4$0.2 2.0$0.1 1.9$0.1
20
CHIANG, WU, AND KO
FIG. 1. The BaP contents of fumes from various cooking oils with or without fume extractor.
CARCINOGENIC CONTENTS OF COOKING OIL FUMES
1.8$0.3, and 2.5$0.1 lg/m3 in fumes from saf8ower oil, 21.6$1.3, 3.2$0.1, 2.6$0.2, and 2.1$0.4 lg/m3 in vegetable oil, and 18.7$0.9, 2.4$0.2, 2.0$0.1, and 1.9$0.1 lg/m3 in corn oil, respectively. The identi7ed PAHs were analyzed in fumes from cooking oils collected in the presence of the tabletop fume extractor. Under these conditions, concentrations of BaP were signi7cantly decreased (P:0.05). The average reduction in percentage was 75% (Fig. 1). The other identi7ed PAHs were not detected in HPLC analysis.
DISCUSSION
Our 7nding that fumes produced by heating cooking oils contain carcinogenic components is in accordance with earlier studies (Chiang et al., 1997; Qu et al., 1992; Shields et al., 1995). We successfully identi7ed four PAHs in fumes from these cooking oils. BaP, DBahA, and BaA are considered probable human carcinogens (group 2A); BbFA is considered a possible human carcinogens (group 2B) by IARC (1992). Exposure to PAHs is considered an etiologic factor of lung cancer (Boffetta et al., 1997). Saf8ower oil, vegetable oil, and corn oil are frequently used by cooks in Taiwan and during the past 10 years. These results indicated that exposure to cooking oil fumes could possibly increase exposure to PAHs, which may be linked to the increased risk of lung cancer reported in Chinese Women. The concentration of B[a]P in cooking oil fumes exceeds that reported in cigarette smoke by a factor of 6.5 times (Guerrin 1993). The mutagenicity of cooking oil fumes can be signi7cantly reduced by using a fume extractor, which is designed for kitchen use in the style of a ‘‘low side wall’’ by ACGIH (1986), as shown in a previous study (Chiang et al., 1998). However, the distance between fume extractor and the cooking pot surface is important. At 70 cm, the ef7ciency of the fume extractor was somewhat limited. At 50 cm, the air samples collected by personal sampler were still positive in mutagenicity tests. In this article, we evaluated another ventilation system, a tabletop fume extractor, which is placed directly near the cooking pot with the exhaust fan near the cooking surface, as usually used in Taiwanese restaurants. The results of this intervention indicated that most of the PAHs were reduced to an undetectable level, and levels of BaP were signi7cantly reduced. The tabletop fume extractor can collect cooking fumes before they reach the nose. A comparison between the two ventilation systems was done in
21
our laboratory (data not shown) and showed that the reduction (75%) in BaP by the tabletop fume extractor was much greater than that by the ‘low side wall’ fume extractor (46%). Our study indicates that the use of fume extractors in kitchens, a wide practise in Taiwan but not in mainland China, can reduce exposure to cooking fumes. The risk of contracting cancer for nonsmoking women appears to be associated with preparing meals in kitchens not equipped with a fume extractor (Ko et al., 1997). Teschke et al. (1989) indicated that the air velocity near the face of the person cooking was decreased by the distance between the fume extractor and the face. It is now recommended that a fume extractor system be designed for home kitchens in a new model similar to the tabletop fume extractor equipment in restaurants. The three oils contain more than 65% of unsaturated fatty acids, which oxidize at high temperatures to produce pyrolysates (Tsai and Huang 1993). It is reasonable to predict that cooking oil fumes would contain heterocyclic aromatic amines (HAAs), volatile organic compounds (VOCs), and other PAHs in addition to the compounds measured here. Further study with laboratory animals is needed to explore the carcinogenicity of this mixture.
REFERENCES American Conference of Governmental Industrial Hygienists. (1986). ‘‘Industrial Ventilation, A Manual of Recommended Practice,’’ 19th. Ed. Edwards, Ann Arbor, MI. Boffetta, P., Jourenkova, N., and Gustavsson, P. (1997). Cancer risk from occupational and environmental exposure to polycyclic aromatic hydrocarbons. Cancer Causes Control 8, 444}472. Chiang, T. A., Wu, P. F., and Ko, Y. C. (1998). Prevention of exposure to mutagenic fumes produced by hot cooking oils in Taiwanese kitchens. Environ. Mol. Mutagen. 31, 92}96. Chiang, T. A., Wu, P. F., Wang, L. F., Li, C. H., and Ko, Y. C. (1997). Mutagenicity and polycyclic aromatic hydrocarbon content of fumes from heated cooking oils produced in Taiwan. Mutation Res. 381, 157}161. Gao, Y. T., Blot, W. J., and Zheng, W. (1987). Lung cancer among Chinese women. Int. J. Cancer 40, 604}609. Gao, Y. T., Blot, W. J., and Zheng, W. (1988). Lung cancer and smoking in Shanghai. Int. J. Epidemiol. 17, 277}280. Gere, A. (1982). Decrease in essential fatty acid content of edible fats during the frying process. Z. Ernahrungswiss. 21, 191}201. Guerrin, M. R. (1993). Environment tobacco smoke exposure assessment. In ‘‘Tobacco smoke.’’ Springer-Verlag, New York. IARC. (1992). ‘‘IARC Working Group on the Evaluation on Carcinogenic Risk to Humans: Occupational Exposures to Mists and Vapors from Strong Inorganic Acids and Other Industrial Chemicals,’’ Vol. 54. IARC, Lyon.
22
CHIANG, WU, AND KO
King, H., and Haenszel, W. (1973). Cancer mortality among foreign and native born Chinese in the United States. J. Chron. Dis. 26, 623}646. Ko, Y. C., Lee, C. H., Chen, M. J., Huang, C. C., Chang, W. Y., Lin, H. J., Wang, H. Z., and Chang, P. Y. (1997). Risk and protective factors for primary lung cancer among nonsmoking women in Taiwan. Int. J. Epidemiol. 26, 24}31. Koo, L. C., Ho, J. H. C., and Lee, N. (1985). An analysis of some risk factors for lung cancer in Hong Kong. Int. J. Cancer 35, 149}155. Law, C. H., Day, N. E., and Stanmugaratnam, K. (1976). Incidence rates of speci7c histological types of lung cancer in Singapore Chinese dialect groups, and their aetiological signi7cance. Int. J. Cancer 17, 304}309. Li, S. G., Pan, D. F., and Wang, G. X. (1994). Analysis of polycyclic aromatic hydrocarbons in cooking oil fumes. Arch. Environ. Health 49, 19}122. Loeb, L. A., Enster, V. L., Warner, K. E., Abboffs, J., and Lagazlo, J. (1984). Smoking and lung cancer: An overview. Cancer Res. 44, 5940}5948. Lofroth, G., Stensman, C., and Bradhorst-Satzkorn, M. (1991). Indoor sources of mutagenic aerosol particulate matter: smoking, cooking and incense burning. Mutat. Res. 261, 21}28. MacLennan, R., DaCosta, J., and Day, N. E. (1977). Risk factors for lung cancer in Singapore, Chinese, a population with high female incidence rates. Int. J. Cancer 20, 854}860. Maron, D. M., and Ames, B. N. (1983). Revised methods for the Salmonella mutagenicity test. Mutat. Res. 113, 173}215.
McCredie, M., and Coutes, M. S. (1989). ‘‘Cancer Incidence in Migrants to New South Wales, 1972 to 1984.’’ NSW Central Cancer Registry, Sydney, NSW Cancer Council. Menon, M. A., and Saw, H. S. (1979). Lung cancer in Malaysia. Thorax 34, 269}273. Qu, Y. H., Xu, G. X., Zhou, J. Z., Chen, T. D., Zhu, L. F., Shields, P. G., Wang, H. W., and Gao, Y. T. (1992). Genotoxicity of heated cooking oil vapors. Mutat. Res. 298, 105}111. Shields, P. G., Xu, G. X., Blot, W. J., Fraumeni. J. J. F., Trivers, G. E., Pellizzari, E. D., Qu, Y. H., Gao, Y. T., and Harris, C. C. (1995). Mutagens from heated Chinese and U. S. cooking oils. J. Natl. Cancer Inst. 87, 836}841. Teschke, K., Hertzman, C., Netten, C. V., Lee, E., Morrision, B., Corrista, A., Lau, G., and Hundal, A. (1989). Potential exposure of cooks to airborne mutagens and carcinogens. Environ. Res. 50, 296}308. Tsai, W. B., and Huang, P. C. (1993). Analysis of variously saturated fatty acid contents in some high fat commercial processed foods. Food Sci. 20, 178}186. Wu, P. F., Chiang, T. A., and Ko, Y. C. (1999). Genotoxicity of fumes from heated cooking oils produced in Taiwan. Environ. Res. (in press). Wu-Williams, A. H., Dai, X. D., Blot, W., Xu, Z., and Sun, X. W. (1990). Lung cancer among women in northeast China. Br. J. Cancer 62, 982}987. Yang, S. P., Luh, K. T., and Kuo, S. H. (1984). Chronological observation of epidemiological consideration: A 30-year consecutive study. Jpn. J. Clin. Oncol. 14, 7}19.
Identification of Carcinogens in Cooking Oil Fumes Tai-An Chiang,* 1 Pei-Fen Wu,- ? and Ying-Chin Ko? *Department of Medical Technology, China Junior College of Medical Technology, No. 1, 54 Lane, Wen-Hwa Road, Jen-Te, Tainan, Taiwan; -Department of Industrial Safety and Hygiene, Ta-Jen Junior College of Pharmacy, Pingtung, Taiwan; and ?Graduate Institute of Medicine, Kaohsiung Medical College, Kaohsiung, Taiwan Received December 29, 1997
women in Western and Southeastern countries (King and Haenszel, 1973; McCredie and Coutes, 1989; Koo et al., 1985; Menon and Saw, 1979; Maclennan et al., 1977; Gao et al., 1987). These women smoke little but contract lung cancer rather frequently. Early pathological investigation (Law et al., 1976) showed that Chinese women tend to contract adenocarcinoma, rather than squamous cell carcinoma, implying that the cause of lung cancer in these women may not be smoking. Epidemiological surveys indicated that indoor air contamination deriving from cooking practices might be a important risk factor for lung cancer in Chinese women (Gao et al., 1988; Wu-Williams et al., 1990). Ko et al. (1997) found an 8.3-fold excess risk to contract lung cancer among nonsmoking women exposed to fumes from various cooking oils used for preparing Chinese food without a fume extractor. Experimental studies (Gere, 1982; Teschke et al., 1989) indicate that air samples from restaurant kitchens were mutagenic. Recently, researchers in the People’s Republic of China found that vapors from rapeseed oils were mutagenic (Li et al., 1994; Qu et al., 1992; Shields et al., 1995). According to our previous study, dose-related genotoxicity [sister chromatid exchange (SCE) and SOS] was found for the fumes of several cooking oils (Wu et al., 1998). The mutagenicity of cooking oil exposures was signi7cantly reduced by several methods of fume extraction (Chiang et al., 1998). However, the mutagenic polycyclic aromatic hydrocarbons (PAHs) in fumes from cooking oils, and the variation in carcinogenic contents of cooking oil fumes after fume extraction were not characterized. The purpose of this study was to investigate the PAH content in fumes from six cooking oils, frequently used by Taiwanese women, and to evaluate the ef7cacy of tabletop fume extractors in reducing the toxicity of fumes from these cooking oils.
According to earlier studies, fumes from cooking oils were found to be genotoxic in several shortterm tests such as the Ames test, sister chromatid exchange, and SOS chromotest. Fume samples from six different commercial cooking oils (safBower, olive, coconut, mustard, vegetable, and corn) frequently used in Taiwan were collected. Polycyclic aromatic hydrocarbons (PAHs) were extracted from the air samples and identiAed by high-performance liquid chromatography and conArmed by gas chromatography/mass spectrometry. Extracts of fumes from safBower oil, vegetable oil, and corn oil contained benzo[a]pyrene (BaP), dibenz[a, h]anthracene (DBahA), benzo[b]Buoranthene (BbFA), and benzo[a]anthracene (BaA). Concentrations of BaP, DbahA, BbFA, and BaA were 2.1, 2.8, 1.8, and 2.5 lg/m3 in fumes from safBower oil; 2.7, 3.2, 2.6, and 2.1 lg/m3 in vegetable oil; and 2.6, 2.4, 2.0, and 1.9 lg/m3 in corn oil, respectively. The authors constructed models to study the efAcacy of table-edged fume extractors used commonly by Taiwanese restaurants. Concentrations of BaP were signiAcantly decreased when the fume extractor was working (P:0.05) and the average reduction in percentage was 75%. The other identiAed PAHs were undetected. These results indicated that exposure to cooking oil fumes could possibly increase exposure to PAHs, which may be linked to an increased risk of lung cancer. The potential carcinogenic exposure could be reduced by placing table-edged fume extractors near cooking pots. 1999 Academic Press Key Words: carcinogens; cooking oil fumes; fume extractor.
INTRODUCTION
There is a high incidence of lung cancer in Taiwanese women (Tang et al., 1984) and Chinese To whom correspondence should be addressed. Fax: 886-62605598. E-mail: [email protected]. 18 0013-9351/99 $30.00 Copyright 1999 by Academic Press All rights of reproduction in any form reserved.
19
CARCINOGENIC CONTENTS OF COOKING OIL FUMES
MATERIALS AND METHODS
Sampling Six commercial cooking oils (saf8ower, olive, coconut, mustard, vegetable, and corn) were purchased at a traditional Taiwanese market. These oils were certi7ed by the system of Good Manufacturing Practice (GMP) designed by the Taiwan government (Economic Department Food Good Manufacturing Practice Promotion Organization). Each oil (200 ml) was poured into a 8-cm-diameter iron pot and heated to 250$10@C. Particulates arising from the heated oil samples were collected for 30 min on 37-mm Grade AA glass 7ber 7lter paper by means of a personal sampling pump (8ow rate, 2 liters/min) placed 50 cm above the fuming surface. Another experiment was performed in the presence of a fume extractor. The tabletop fume extractor had a volume 8ow rate of 250 liters/s and was placed 15 cm away from the cooking pot. Each experiment was performed in triplicate.
TABLE 1 Comparison of the Amounts of Fume Particulates from Various Cooking Oils Heated at 250$10@C for 30 min
Cooking oil Saf8ower Olive Coconut Mustard Vegetable Corn
Fume particulate (mg/m3)
Acetone extract (mg/m3 )
24.2$1.3 20.3$0.8 20.8$1.1 21.5$0.9 23.8$1.1 22.4$1.2
21.8$1.2 17.6$1.1 17.1$1.3 18.4$1.1 21.1$1.4 20.2$1.1
wavelength of 306/398 nm. Gas chromatography/ mass spectrometry (GC/MS) was conducted using a HP 5890 Series II instrument equipped with split/ splitless injector and a PTE 5 Supelco 30 cm; 0.25 mm column (0.2 lm). An HP-MSD 5972 mass detector was used as detector and an HP-chemstation-MS as integrator.
Extraction
Statistical Analysis
The 7lter paper was weighed before and after sampling. Each 7lter paper was divided into 1-cm squares with a paper cutter and the pieces were extracted with 100-ml acetone in a shaker. The organic extract was 7ltered through Whatman No. 2 7lter paper, concentrated to about 10 ml in a rotating evaporator at 40@C, and evaporated to dryness under nitrogen. The solid residue was weighed, redissolved in acetone, and stored at !80@C until HPLC analyses were undertaken.
Statistical evaluations were performed using analysis of variance; P:0.05 was considered signi7cant.
PAHs Analysis by HPLC and GC/MS Extracts of samples were passed through a Sephadex LH-20 column (15 mm i.d.;190 mm) at a 8ow rate of 1.5 ml/min, with 2-propanol as eluant. Fractions were collected by a fraction collector at 2-min intervals. An aliquot (10 ll) of each fraction was evaporated and the residue was dissolved in 0.1 ml DMSO for determination of 16 PAHS by HPLC. The fractions were injected into a Supelco LC-PAH column and eluted at a 8ow rate of 2 ml/min, with a linear gradient of 50}100% acetonitrile in water, for 14 min, and held at 100% acetonitrile for an additional 20 min. The resultant peaks were compared with standard calibration curves and deconvoluted by the program in HP Chem Station (Hewlett Packard Co.) Peak areas were used to calculate the concentration of PAHs. The PAHs were monitored by 8uorescence at a
RESULTS
The recovery rates of PAHs analysis by HPLC ranged from 91 to 97%. PAHs were undetectable before the cooking oils were heated. The highest mass of fume particulate was obtained from saf8ower oil, followed by vegetable oil, corn oil, mustard oil, coconut oil, and olive oil (Table 1). Saf8ower oil also yielded the highest amount of solute in the acetone extract. Extracts of fumes from saf8ower oil, vegetable oil, and corn oil contained BaP, DBahA, BbFA, and BaA (Table 2). Concentrations of BaP, DBahA, BbFA, and BaA were 22.7$1.5, 2.8$0.2,
TABLE 2 The Carcinogenic Contents (lg/m3 ) of Fumes from Various Oils Heated to 250$10@C for 30 min Cooking oil Carcinogens
Saf8ower
Vegetable
Corn
BaP DBahA BbFA BaA
22.7$1.5 2.8$0.2 1.8$0.3 2.5$0.1
21.6$1.3 3.2$0.1 2.6$0.2 2.1$0.4
18.7$0.9 2.4$0.2 2.0$0.1 1.9$0.1
20
CHIANG, WU, AND KO
FIG. 1. The BaP contents of fumes from various cooking oils with or without fume extractor.
CARCINOGENIC CONTENTS OF COOKING OIL FUMES
1.8$0.3, and 2.5$0.1 lg/m3 in fumes from saf8ower oil, 21.6$1.3, 3.2$0.1, 2.6$0.2, and 2.1$0.4 lg/m3 in vegetable oil, and 18.7$0.9, 2.4$0.2, 2.0$0.1, and 1.9$0.1 lg/m3 in corn oil, respectively. The identi7ed PAHs were analyzed in fumes from cooking oils collected in the presence of the tabletop fume extractor. Under these conditions, concentrations of BaP were signi7cantly decreased (P:0.05). The average reduction in percentage was 75% (Fig. 1). The other identi7ed PAHs were not detected in HPLC analysis.
DISCUSSION
Our 7nding that fumes produced by heating cooking oils contain carcinogenic components is in accordance with earlier studies (Chiang et al., 1997; Qu et al., 1992; Shields et al., 1995). We successfully identi7ed four PAHs in fumes from these cooking oils. BaP, DBahA, and BaA are considered probable human carcinogens (group 2A); BbFA is considered a possible human carcinogens (group 2B) by IARC (1992). Exposure to PAHs is considered an etiologic factor of lung cancer (Boffetta et al., 1997). Saf8ower oil, vegetable oil, and corn oil are frequently used by cooks in Taiwan and during the past 10 years. These results indicated that exposure to cooking oil fumes could possibly increase exposure to PAHs, which may be linked to the increased risk of lung cancer reported in Chinese Women. The concentration of B[a]P in cooking oil fumes exceeds that reported in cigarette smoke by a factor of 6.5 times (Guerrin 1993). The mutagenicity of cooking oil fumes can be signi7cantly reduced by using a fume extractor, which is designed for kitchen use in the style of a ‘‘low side wall’’ by ACGIH (1986), as shown in a previous study (Chiang et al., 1998). However, the distance between fume extractor and the cooking pot surface is important. At 70 cm, the ef7ciency of the fume extractor was somewhat limited. At 50 cm, the air samples collected by personal sampler were still positive in mutagenicity tests. In this article, we evaluated another ventilation system, a tabletop fume extractor, which is placed directly near the cooking pot with the exhaust fan near the cooking surface, as usually used in Taiwanese restaurants. The results of this intervention indicated that most of the PAHs were reduced to an undetectable level, and levels of BaP were signi7cantly reduced. The tabletop fume extractor can collect cooking fumes before they reach the nose. A comparison between the two ventilation systems was done in
21
our laboratory (data not shown) and showed that the reduction (75%) in BaP by the tabletop fume extractor was much greater than that by the ‘low side wall’ fume extractor (46%). Our study indicates that the use of fume extractors in kitchens, a wide practise in Taiwan but not in mainland China, can reduce exposure to cooking fumes. The risk of contracting cancer for nonsmoking women appears to be associated with preparing meals in kitchens not equipped with a fume extractor (Ko et al., 1997). Teschke et al. (1989) indicated that the air velocity near the face of the person cooking was decreased by the distance between the fume extractor and the face. It is now recommended that a fume extractor system be designed for home kitchens in a new model similar to the tabletop fume extractor equipment in restaurants. The three oils contain more than 65% of unsaturated fatty acids, which oxidize at high temperatures to produce pyrolysates (Tsai and Huang 1993). It is reasonable to predict that cooking oil fumes would contain heterocyclic aromatic amines (HAAs), volatile organic compounds (VOCs), and other PAHs in addition to the compounds measured here. Further study with laboratory animals is needed to explore the carcinogenicity of this mixture.
REFERENCES American Conference of Governmental Industrial Hygienists. (1986). ‘‘Industrial Ventilation, A Manual of Recommended Practice,’’ 19th. Ed. Edwards, Ann Arbor, MI. Boffetta, P., Jourenkova, N., and Gustavsson, P. (1997). Cancer risk from occupational and environmental exposure to polycyclic aromatic hydrocarbons. Cancer Causes Control 8, 444}472. Chiang, T. A., Wu, P. F., and Ko, Y. C. (1998). Prevention of exposure to mutagenic fumes produced by hot cooking oils in Taiwanese kitchens. Environ. Mol. Mutagen. 31, 92}96. Chiang, T. A., Wu, P. F., Wang, L. F., Li, C. H., and Ko, Y. C. (1997). Mutagenicity and polycyclic aromatic hydrocarbon content of fumes from heated cooking oils produced in Taiwan. Mutation Res. 381, 157}161. Gao, Y. T., Blot, W. J., and Zheng, W. (1987). Lung cancer among Chinese women. Int. J. Cancer 40, 604}609. Gao, Y. T., Blot, W. J., and Zheng, W. (1988). Lung cancer and smoking in Shanghai. Int. J. Epidemiol. 17, 277}280. Gere, A. (1982). Decrease in essential fatty acid content of edible fats during the frying process. Z. Ernahrungswiss. 21, 191}201. Guerrin, M. R. (1993). Environment tobacco smoke exposure assessment. In ‘‘Tobacco smoke.’’ Springer-Verlag, New York. IARC. (1992). ‘‘IARC Working Group on the Evaluation on Carcinogenic Risk to Humans: Occupational Exposures to Mists and Vapors from Strong Inorganic Acids and Other Industrial Chemicals,’’ Vol. 54. IARC, Lyon.
22
CHIANG, WU, AND KO
King, H., and Haenszel, W. (1973). Cancer mortality among foreign and native born Chinese in the United States. J. Chron. Dis. 26, 623}646. Ko, Y. C., Lee, C. H., Chen, M. J., Huang, C. C., Chang, W. Y., Lin, H. J., Wang, H. Z., and Chang, P. Y. (1997). Risk and protective factors for primary lung cancer among nonsmoking women in Taiwan. Int. J. Epidemiol. 26, 24}31. Koo, L. C., Ho, J. H. C., and Lee, N. (1985). An analysis of some risk factors for lung cancer in Hong Kong. Int. J. Cancer 35, 149}155. Law, C. H., Day, N. E., and Stanmugaratnam, K. (1976). Incidence rates of speci7c histological types of lung cancer in Singapore Chinese dialect groups, and their aetiological signi7cance. Int. J. Cancer 17, 304}309. Li, S. G., Pan, D. F., and Wang, G. X. (1994). Analysis of polycyclic aromatic hydrocarbons in cooking oil fumes. Arch. Environ. Health 49, 19}122. Loeb, L. A., Enster, V. L., Warner, K. E., Abboffs, J., and Lagazlo, J. (1984). Smoking and lung cancer: An overview. Cancer Res. 44, 5940}5948. Lofroth, G., Stensman, C., and Bradhorst-Satzkorn, M. (1991). Indoor sources of mutagenic aerosol particulate matter: smoking, cooking and incense burning. Mutat. Res. 261, 21}28. MacLennan, R., DaCosta, J., and Day, N. E. (1977). Risk factors for lung cancer in Singapore, Chinese, a population with high female incidence rates. Int. J. Cancer 20, 854}860. Maron, D. M., and Ames, B. N. (1983). Revised methods for the Salmonella mutagenicity test. Mutat. Res. 113, 173}215.
McCredie, M., and Coutes, M. S. (1989). ‘‘Cancer Incidence in Migrants to New South Wales, 1972 to 1984.’’ NSW Central Cancer Registry, Sydney, NSW Cancer Council. Menon, M. A., and Saw, H. S. (1979). Lung cancer in Malaysia. Thorax 34, 269}273. Qu, Y. H., Xu, G. X., Zhou, J. Z., Chen, T. D., Zhu, L. F., Shields, P. G., Wang, H. W., and Gao, Y. T. (1992). Genotoxicity of heated cooking oil vapors. Mutat. Res. 298, 105}111. Shields, P. G., Xu, G. X., Blot, W. J., Fraumeni. J. J. F., Trivers, G. E., Pellizzari, E. D., Qu, Y. H., Gao, Y. T., and Harris, C. C. (1995). Mutagens from heated Chinese and U. S. cooking oils. J. Natl. Cancer Inst. 87, 836}841. Teschke, K., Hertzman, C., Netten, C. V., Lee, E., Morrision, B., Corrista, A., Lau, G., and Hundal, A. (1989). Potential exposure of cooks to airborne mutagens and carcinogens. Environ. Res. 50, 296}308. Tsai, W. B., and Huang, P. C. (1993). Analysis of variously saturated fatty acid contents in some high fat commercial processed foods. Food Sci. 20, 178}186. Wu, P. F., Chiang, T. A., and Ko, Y. C. (1999). Genotoxicity of fumes from heated cooking oils produced in Taiwan. Environ. Res. (in press). Wu-Williams, A. H., Dai, X. D., Blot, W., Xu, Z., and Sun, X. W. (1990). Lung cancer among women in northeast China. Br. J. Cancer 62, 982}987. Yang, S. P., Luh, K. T., and Kuo, S. H. (1984). Chronological observation of epidemiological consideration: A 30-year consecutive study. Jpn. J. Clin. Oncol. 14, 7}19.