Tohoku J. exp. Med., 1976, 119, 353-356

Mercury in

TSUGUYOSHI SUZUKI, SACHIKO SHISHIDO and KENJI URUSHIYAMA Department of Public Health, Tohoku University School of Medicine, Sendai

, T., SHISHIDO, S. and URUSHIYAMA, K. Mercury in Cigarettes. Tohoku J. exp. Med., 119 (4), 353-356 Mercury in cigarettes of domestic and foreign products was measured by Magos' method, and the sample of a domestic brand was burned by a machine and the smoke was collected for the measurement of mercury. In leaf and paper, only inorganic mercury was found in both domestic and foreign products. Its amount in tobacco leaf and paper of a piece of was about 60 ƒÊg in domestic products and about 30 ƒÊg in foreign products. By burning, the unit length of a cigarette released about 5-7 ƒÊg of mercury into smoke. mercury; cigarettes; smoking.

In view of the report that the total mercury concentrations in cigarettes were 0.2-2.0 ƒÊg/g in domestic products and 0.08-0.34 ƒÊg/g in foreign products (Fujii

et al. 1973), it was planned to examine the contribution of smoking to human

mercury uptake.

SAMPLES AND METHODS

Cigarettes of different brands were purchased from ordinary retailers in Sendai City in July 1975. All the cigarettes purchased were filter-cigarettes. Organic mercury and inorganic mercury were separately measured by Magos' method (1971) in the samples of tobacco leaf, paper and filter. Samples were homogenized in a solution of 45% NaOH and 1% L-cysteine-HCl by glass homogenizer, and the homogenate was measured by flameless atomic absorption spectrometry. To measure the amount of mercury in smoke, a simple smoking machine (Fig. 1) was used. The mercury in smoke was trapped in two serially connected impingers containing each 8 ml of the solution of 1 N H2S04 and 0.5% KMnO4. After smoking experiments, mercury was found only in the first impinger. Smoking experiments were repeated twice: in the first experiment, puff (drawing-in) volume, puff frequency, puff (drawing-in) duration, and smoked length of cigarettes were 100 ml, 0.5/min, 10-15 seconds, and 2.5 3.5 cm, respectively, and in the second experiment, those were 35 ml, 1/min, 2-3 seconds, and 5 cm. After smoking by the machine, butt (leaf and paper), filter, and ash (a collection from 3 or 5 smoked cigarettes) were measured in a way similar to the case of non-smoked cigarettes. The solution of mercury trap was measured after addition of a slight excess of 20% hydroxylamine hydrochloride solution.

Received for publication, March 10, 1976. 353

SUZUKI 354 T. Suzuki et al.

Fig. 1. A smoking machine used for the present experiment. Lighted cigarettes were puffed by drawing out the piston of glass syringe (the volume was 100 ml) up to a fixed volume, disconnecting the syringe from the impinger, drawing in the piston to the syringe, and connecting again the syringe to the impinger. All procedures were manually conducted. Mercury in smoke was trapped into the solution of 1 N H2S04 and 0.5% KMnO4 in the impinger (the volume was 20 ml).

RESULTS Mercury in non-smoked cigarettes (Table 1)

Organic mercury was not found in any samples. Domestic products had significantly greater amounts and concentrations of inorganic mercury in tobacco leaf, and filter, but not in paper, than foreign products.

Mercury in smoke (Table 2)

Organic mercury was detected only in the filter of cigarettes from the package used for the experiment 1. Organic mercury was, however, disregarded in the

TABLE 1. Inorganic mercury in non-smoked cigarettes

Numerals in the table are mean+standard deviation. n.s.: not significant. Each one cigarette was sampled from a package of different brands such as "Peace", "Marina" , "Hi-lite", "Seven Stars", "Luna", "Cherry" and "Hope" in the case of domestic products, and "No. 6", "Atika", "" and "Rothman" in the case of foreign products. Mercury in Cigarettes 355

TABLE 2. Mercury in cigarettes before and after smoking

Numerals in the table are the mean of 3 cigarettes in the experiment 1, and the mean of 5 cigarettes in the experiment 2. The brand of cigarettes is "Peace" in both experiments . Experimental conditions are described in the text. I-Hg: inorganic mercury; O-Hg: orgnanic mercury; n.d.: not detected; -. no measurement. * Leaf and paper. f Calculated values.

smokiug experiment, because the compound contained in the filter would not have any meaniug for mercury uptake of man. Accordiug to the smoked leugth of cigarettes, the amount of mercury in smoke varied from 13.9 to 34.3 ng. The unit leugth (1 cm, ca. 140 mg of leaf and 6 mg of paper) of cigarettes, when smoked, released about 5 ng of mercury into smoke in the experiment 1, and 7 ng in the experiment 2.

DISCUSSION

Mercury concentrations in domestic cigarettes had decreased from about 1.0-2.0 ƒÊg/g in 1966 to 0.2-1.0 ƒÊg/g in 1971 (Fujii et al. 1973). These results were for total mercury, and tobacco leaf, paper, and filter were not examined separately from each other in the measurement. Thus, the direct comparison of their data with the results of the present study is impossible, but the levels of mercury in the present results are much lower than the data reported previously. Mercury-containing seed disinfectants should have been an important source of mercury contamination in the tobacco leaf. Since 1967 the use of mercurials as seed disinfectants has been recommended by the government to be replaced by other chemicals such as organophosphorus compounds or antibiotics. The decrease of mercury concentrations in tobacco leaf is considered as a result of enactment of this recommendation. Domestic products have shown higher levels of mercury in tobacco leaf and filter than foreign products. The cause is not clear, but the mercury-containing 356 T. Suzuki et al, fungicide is a suspect. The release of mercury into smoke is primarily a function of mercury concentrations in tobacco leaf and paper, but physico-chemical properties of cigarettes and smoking habits of individual smokers influence the amount of smoke produced as well as the release of mercury into smoke. In the present results, the filter attached to cigarettes was partly effective in trapping mercury, but the amount of mercury found in smoke was 30-50% of the total amount contained in the entire leaf and naner of a cigarette.

The smoke from burning cigarettes is understood as an uncommonly con centrated aerosol, in which the size of the particles ranges 0.1-1.0ƒÊm (Wynder and

Hoffmann 1967). In what state mercury exists in the smoke is unknown. It may be vaporized or combined to some chemicals by burning. If it is in the state of vapor, 75-85% of mercury will be retained in the human body, and the amount of mercury deposited may be smaller in the state of aerosol (Nordberg and

Skerfvine 1972). The daily amount of mercury retained in the body by cigarette smoking will be 336 ng, provided that 20 cigarettes are consumed per day, 60 ng of inorganic mercury are contained in tobacco leaf and paper of a cigarette, 3.5 czn of each piece of cigarettes are smoked, 6 ng of mercury are released in smoke per unit length of cigarettes, and 80% of mercury in smoke are retained in the human body. Needless to say, this single figure is just an approximation based on various assumptive values which do not necessarily represent the standard for individual smokers. Studies on mercury in expired air, and the difference in mercury accumulation between smokers and non-smokers are our next concerns.

Acknowledgment

This study was supported by the grant from the Ministry of Education, Japan.

References 1) Fujii, M., Kitamura, M. & Kondo, M. (1973) Suigin no bunpu to taikichyu no suigin ni tsuite (Distribution of mercury and mercury in air). Kankyo Hoken Report (Env . Health Report) (Jap.), 26, 5-47. 2) Magos, L. (1971) Selective atomic-absorption determination of inorganic mercury and methylmercury in undigested biological samples. Analyst, 96, 847-853. 3) Nordberg, G.E. & Skerfving, S. (1972) Metabolism. In: Mercury in the Environment, edited by L. Friberg & D. Vestal, The Chemical Rubber Co., Cleveland, pp. 29-91. 4) Wynder, E,L. & Hoffmann, D. (1967) Tobacco and Tobacco Smoke, Studies in Experimental Carcinogenesis, Academic Press, New York and London .