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Dioxins in Cigarette Smoke 

H. MUTO et al
Archives of Environmental Health, Pg. 44 (3) : 171-4 May/Jun89

 

H. Muto
Y. Takazawa
Department of Public Health
Akita University School of Medicine
Akita, Japan 

Abstract: 
Dioxins in cigarettes, smoke, and ash were determined using gas chromatography/mass spectrometry. The total concentration of polychlorinated dibenzo-p-dioxins (PCDDs) in cigarette smoke was approximately 5.0 µ/m3 at the maximum level, whereas various cogeners from tetra-octa-chlorodibenzo-p-dioxin ( -CDD) were detected. Particularly, the total concentration of hepta-CDD cogeners was the highest among these cogeners. Mass fragmentograms of various PCDD cogeners were similar to those in flue gas samples collected from a municipal waste incinerator. The PCDD cogeners that were not present in the cigarettes were found in the smoke samples. The 2, 3, 7, 8-TCDD toxic equivalent value---an index for effects on humans—for total PCDDs in smoke was 1.81 nng/m3 using the toxic factor of the United States Environmental Protection Agency. Daily intake of PCDDs by smoking 20 cigarettes was estimated to be approximately 4.3 pg. kg body/weight/day. This value was close to that of the ADIs: 1-5 pg. kg body/weight/day reported in several countries. A heretofore unrecognized health risk was represented by the presence of PCDDs in cigarette smoke.

 

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are hazardous compounds, arid because of their undisputed highly toxic effects, their presence in the environment constitutes serious public health problem. Environmental pollution from PCDDs by disposal of chemical wastes1 and electrical PCB accident2-3 has been reported the PCDD concentrations in human tissues,4-6 mother's milk,7 and dietary foods8,9 have also been discussed by many investigators. The concentrations of PCDDs and PCDFs in daily foods have been determined and are reported elsewhere.10 The concentration of PCDDs and PCDFs in fish, eggs, meats, and 'dairy products was higher than concentrations found in other food items ingested daily.

For sources of PCDDs and PCDFs leading to environmental and human pollution, risk assessments by toxic equivalents predicated from toxic factors in various countries are being concluded. 11-15 However, the presence of PCDDs in cigarettes and cigarette smoke has not yet been reported.

Rappe et al.16 reported that PCDDs and PCDFs can be formed in pyrolytic processes of various incinerators where material containing chlorinated phenols, polychlorinated biphenyls, polybrominated biphenyls, aid polyhalogenated diphenyl ethers are incinerated. Cigarette smoke contains hazardous organic compounds such as benzo(a)pyrene, dimethylnitrosamine, and N'-nitroso-N-nicotine. Thus, we have conducted experiments to ascertain whether PCDDs are present in cigarettes or in cigarette smoke.

Methods

Apparatus.  
A schematic diagram of the sampling method for PCDDs in cigarette smoke is shown in Figure 1. Smoke was drawn through traps continuously by an air pump at a flow rate of 1.2-1.5 l/min. A cigarette was burned from its top to 10 mm from its filter. Polychlorinated dibenzo-p-dioxins in smoke were trapped with a glass fiber filter (GFP), polyurethane foam (polyether type, density - 0.016 g/cm3), and XAD-11 resin, successively. The GFP was set in front of the polyurethane foam. The 30-ml XAD-11 resin was packed in a thimble filter and inserted into another glass pipe. The glass pipes were sealed with silicone rubber stops covered with Teflon films and were connected with Teflon pipes (Fig. 1). Ash resulted from the combustion of 20 cigarettes and was collected for a period of 30 min. and the weight of an ash sample ranged from 1.4 to 1.6 g.

Prior to the experiment, impurities in GFP, urethane foam, and XAD-11 resin used as traps were extracted with acetone and benzene for 24 h using a Soxhlet extractor. In the combustion experiments, urethane foam and XAD-11 resin were useful for trapping PCDDs in cigarette smoke and were used for sampling PCDDs in the atmosphere, and were 88% efficient for the three traps with 1,2,3,4-TCDD as the standard.

Analytical procedure.
A method' of analysis for ash sample is shown in Figure 2. An ash sample of approximately 1.5 g was treated with acid (1N HCI). The residue was extracted by a Soxhlet extractor with 200 ml of benzene. The benzene condensate was treated with sulfuric acid; the PCDDs in condensate were then separated by column chromatography with 5 g of activated alumina. Following column chromatography, the PCDDs were purified with HPLC. The PCDDs in the eluate were extracted with benzene. For gas chromatography/mass spectrometry (GC/MS) SIM analyses, 5 µg of the benzene solution were used. The clean up of PCDDs from GFP, urethane foam, or XAD-11 resin was conducted by subsequent extraction with a Soxhlet. Cigarette samples were treated similarly. The Teflon tube and pipe used for sampling were also washed three times with 200 ml of benzene in a manner similar to that used for the ash sample. A GC/MS (Shimadzu QP-1000, Tokyo, Japan), equipped with a quadrupole type and a solvent cut-split system, was used to determine levels of PCDDs. Guaranteed-grade organic solvents from Wako Pure Chemical, Co. Ltd. (Tokyo, Japan) were used in this study. Internal Standard materials, i.e., 1,2,3,4-TCDD (13C6) and octa-CDC) (13C12) [immediately preceding text blurred on copy] were supplied by Cambridge Isotope Laboratories (Woburn, MA) ,and were used for tile determination of PCDDs. The standard of 20 ng was added to the samples. Conditions for high resolution GC/low resolution MS (HRGC/LRMS) are provided in Table 1.

Fig. 1. A schematic diagram of the sampling method used to determine PCDDs in cigarette smoke.

Results and discussion

Our experimental results for PCDD concentrations and abundance ratios of PCDD isomers in the cigarettes, smoke, and ash sample, which were obtained from a simple sampling apparatus, may differ from those obtained in experiments where the autosmoking machine and the smoking method by international smoking mode are utilized (i.e., 1 puff/min: puff flow rate, 35 ml/2 sec; length of cigarette end, 30 mm). However, the detection of PCDD congeners in cigarette smoke may be important.

Mass fragmentograms of tetra-CDDs in smoke from urethane foam extracts corresponding to 20 cigarettes are shown in Figure 3. Approximately 10 peaks for 22 isomers of tetra-CDDs were identified either in urethane foam extracts or in GFP and XAD-11 resin extracts. However, 2,3,7,11-TCDD was not detected in the smoke, ash, or cigarette samples.

Table 2 shows PCDD concentrations and equivalent values for one kind of cigarette sample and its ash and smoke samples. These results are the sum of the PCDDs in GFP, urethane foam, and XAD-11 resin. The major component of total PCDDs in cigarettes and smoke was hepta-CDD congeners. These hepta-CDD congeners accounted for 84% and 94% of the total PCDDs in cigarettes and smoke, respectively. The 2,3,7,8-hepta-CDD was most abundant among the hepta-CDD isomers. However, the abundance ratio of 2,3,7,8-hepta-CDD was decreased in smoke, whereas that of other hepta-CDD isomers was increased. Although no penta-CDD congeners were detected in the cigarettes, the 2,3,7,8-penta-CDD and other penta-CDD isomers were identified in the smoke samples. These results showed that penta-CDD congeners were formed during combustion of the cigarettes. Further, 2,3,7,8-derivatives of pent-hepta-CDDs accounted for 15% of the total PCDDs.

Table 1. Conditions for High Resolution GC/Low Resolution MS

GC/column packing and temperature:
     Supelco sp-2331, 0.25 mm x 30 l/min
     1800° C - 270° C. rate 6° C/min (internal STD and tetra-CDDs)
     200° C - 270° C. rate 5° C/min (penta- and hexa-CDDs)
     Shimadzu HiCap-CBP-5, 0.25 mm x 15 l/min
     (5% phenylmethylsilicone)
     220° C - 300° C. rate 7° C/min (internal STD, hepta- and octa-CDD)
GC/Injection temp. and carrier gas: 270° C
     He gas, 60 ml/min
MS/ion source and temp.: El mode. 70eV, 250° C
MS/separator temp.: 270° C
Monitor ion: M°, (M + 2)° (isotope ratio: + < 30%)
GC/injection vol.: 5 µl


Fig. 3. Mass fragmentograms of tetrachlorodibenzo-p-dioxins in cigarette smoke (urethane foam extracts).


Fig.2. Analytical procedure used to determine dioxins in ash sample. PCDDs in urethane foam, GFP, and XAD-11 resin were extracted with 200 ml of benzene using a Soxhlet extractor; PCDDs in cigarettes were extracted directly three times with 200 ml benzene.

Ash sample (ca. 1.5 g/20 cigarettes)
        
Treatment with acid 1N HCI, 200 ml
         (shaking)
        
Filtration 
          air-dry
        
Soxhlet extraction benzene, 200 ml: 24 h
          condensation (1 ml)
          n-Hexane, 150 ml
         1,2,3,4-TCDD (13C6). 20 ng
        
Treatment with sulfuric acid
         washing
         K.D. condensation
         N, gas purge (200 µl)
         n-Hexane, 5 ml
        
Column chromatography activated alumina. 5 g
        n-hexane, 50 ml
        n-Hexane + dichloromethane, 70 ml
        distillate of n-hexane + dichloromethane
        K.D. condensation
        
HPLC Zolbax SIL col.
        n-Hexane, 1 ml/min (4-8 min)
        condensation final: benzene, 100 µl
        
GC-MS

To evaluate human effects of PCDDs found in the present samples, the 2,3,7,8-TCDD toxic equivalent values were calculated using U.S. Environmental Protection Agency toxic factors.12 The values were 1.88 pg/g, 1.81 ng/m3, and 0.102 ng/g for the cigarette, smoke, and ash sample, respectively. In the smoke sample, the ratio of equivalent value of 2,3,7,8-penta-CDD isomer produced by combustion accounted for approximately 12% of the total equivalent value. The equivalent value of total PCDDs in cigarette smoke was in agreement with that in flue gas from municipal waste incinerators.17 Further, the daily intake of PCDDs by smoking 20 cigarettes was estimated to be 4.3 pg - kg body weight/day for the 60-kg (132-lb.+) adult. This intake rate was close to those of acceptable daily intakes (ADIs), i.e., 5 pg - kg/day, reported in several countries.18-20 Because the smoker or passive smoker might also inhale and ingest dioxins from other sources, PCDD in. take by smokers or passive smokers may exceed the ADIs for dioxins. A heretofore unrecognized health hazard resulting from the presence of PCDDs, especially lower PCDD congeners, in cigarettes should be considered.

Conclusions

The concentration of PCDDs in cigarette smoke was similar to that found in the flue gas-of a municipal waste incinerator. However, the presence of PCDDs in cigarette smoke is more significant than that in tile flue pas because cigarette smoke is inhaled directly into the lungs without diffusion and/or dilution. Although PCDDs concentration in cigarette smoke is lower than formaldehyde or benzo(a)pyrene concentrations, daily intake of PCDDs by smoking 20 cigarettes was estimated to be about 4.3 pg - kg body weight/day. The value obtained was close to those of the ADIs: 1-5 pg kg body weight/day reported in several countries. the presence of tetra-CDD isomers, except 2,3,7,8.TCDD, was notable. Further, the total concentration of 2,3,7,8-derivatives of penta-hepta-CDD accounted for 15% of the total PCDDs, whereas hepta-CDD congeners were most abundant in smoke (94°/0) and in the original cigarettes (84°/o). The dioxins in the cigarette smoke appear to be volatilized from the cigarettes themselves. Further work needs to be done to characterize the magnitude of the public health problem.

Table 2. Concentrations and Toxic Equivalents of Dioxins in Cigarettes, Smoke, and Ash*

   Concentrations  Toxic equivalents E

Cigarettes
(pg/g)

Smoke
(ng/ml)

Ash
(pg/g)

Cigarettes
(pg/g)

Smoke
(ng/m3)

Ash
(pg/g)

2,3.7,8-TCDD ND L   ND    ND     0  0  0
Other TCDDs 44.9 68.0   4.63  0 4-49  0.68  0.046
2,3,7,8-PeCDO ND    0.43 ND     0  0.215  0
Other PeCDDs ND    1.08 ND     0  0.005  0
2.3,7,8-HxCDDs 2.01 2.15 0.56  0.08  0.086  0.022
Other HxCDDs 11.4 5.36 4.45  0.005  0.002  0.002
2.3,7,8-HpCDOs 1343    783    ND     1.343  0.783  0
Other HpCDDs 286    4156    3211     0.003  0.042  0.032
OCDD 257    240    ND     0  0  0
Total PCDDs 1944    5256    3221     1.88  1.81  0.102
* Values were calculated from 20 cigarettes. 
E Equivalent factor, United States Environmental Protection Agency,12 
L Lower than the limit of detection (0.5 pg/g; 0.22 ng/ml).

Submitted for publication April 5, 1988; revised; accepted for publication August 24, 1988.

Requests for reprints should be sent to: H. Muto, Dept. of Public Health. Akita University School of Medicine, Hondo 1-1-1, Akita 010. Japan.

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- END OF PAPER -

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