Nicotine is the main addictive substance in tobacco. Sixteen brand variants of manufactured cigarettes and 10 brand variants of loose cigarette tobacco were tested for nicotine content (manufactured cigarettes only) and nicotine concentration. The average nicotine content of regular manufactured cigarettes tested was 19.5 mg, approximately twice that in United States and Canadian manufactured cigarettes. Loose cigarette tobacco tended to have a higher nicotine content than manufactured cigarettes. The low priced packs of 10 cigarettes, which is the size most commonly bought by young smokers, had the highest concentration of nicotine among the manufactured cigarettes tested. The nicotine content of New Zealand manufactured cigarettes could be lowered.

New Zealand's 380,000 smokers age 35 and over in 1995 had a one in two chance of dying early if they continue to smoke, standing to lose in total, 2.66 million years of life to cigarettes. Four in five smokers say they are addicted and would find it difficult to give up for a week. Among Dunedin 18-year-old smokers s 56 percent were clinically addicted to nicotine based on American Psychiatric Association criteria. To investigate the scope for modifying tobacco products so as to decrease nicotine addiction in New Zealand, we analysed the nicotine content of manufactured cigarettes and loose cigarette tobacco.

Sixteen brand variants of manufactured cigarettes and 10 brand variants of loose, fine-cut cigarette tobacco were sample (Table 1). Some brand variants differed only in pack size. The cheapest cigarette packs (10s) were included. Twelve different brands of manufactured cigarettes and eight different brands of loose cigarette tobacco, including mild and menthol brands, were represented among the samples. The selected brands accounted for 62% of the manufactured cigarette sales and 74 percent of the loose cigarette tobacco sales by volume in 1996..

All samples were purchased on one occasion at a Petone supermarket in June 1996. The tobacco of half the manufactured cigarettes in a packet and one-quarter of the loose cigarette tobacco in a packet was separated, then homogenised. Nicotine was extracted with ethanol by the Dionexâ Accelerated Solvent Extractor, assayed by Hewlett Packard Gas Chromatograph-Mass Selective Detector, and reported as content per cigarette, and as dry weight concentration per gram of tobacco. The nicotine yield of cigarette smoke was not tested.

* Correspondence: Dr Tony Blakely, ESR Communicable Disease Centre, Box 50148, Porirua. E-mail: tony.blakely@esr.cri.nz

Manufactured cigarettes The nicotine content of the manufactured cigarettes tested ranged from 16.5 to 27.7 mg per cigarette. (Table 1). The highest nicotine content was in a plain cigarette brand. The mean nicotine content for regular (filter) manufactured cigarettes was 19.5 mg per cigarette and 17.5 mg for mild manufactured cigarettes.

The nicotine concentration in manufactured cigarettes ranged from 2.53% to 3.69% by dry weight. (Table 1). The highest nicotine concentration was in a pack of 10. The mean nicotine concentration in regular (filter) manufactured cigarettes was 2.89%, while that in mild manufactured cigarettes was marginally (4.2%) lower at 2.77%. Some manufacturers' mild cigarette brands had a higher nicotine concentration than other manufacturers' regular cigarettes.

Loose cigarette tobacco: The nicotine concentration in the loose cigarette tobacco tested ranged from 2.27% to 4.12% by dry weight. (Table 1). The mean nicotine concentration in regular loose tobacco (3.28%) was 13.5% higher than in regular manufactured cigarettes.

The mean nicotine concentration

Holiday 10s had the highest nicotine content of any filter cigarette and the highest nicotine concentration (the strongest tobacco) of any cigarette. In 1995 this was the top selling brand at the lowest price ($2.60 in December 1995) of any cigarette packet sold. Horizon 10s, the other packet sold at this price, also contained above-average nicotine (Table 1). Holiday brands of pack size 10s, 20s and 25s were tested, but the cheaper- pack-size 10s contained most nicotine per cigarette.

Parliament's Social Services Select Committee in 1996 heard evidence that young adolescents most often asked for packets of ten.13 Because of their price-appeal to young smokers, the Committee recommended that packs of tens be banned, and that the law should clearly allow regulation of harmful constituents in cigarettes or their smoke. This could include nicotine.

The pattern of differences in nicotine content between brands points to control of these differences during manufacture. The highest concentrations of nicotine in cigarettes and in cigarette tobacco were respectively 46 percent and 81 percent higher than lowest-concentration brand variants. Regular brands tended to have higher nicotine than mild brands, within and across brands. Within-brand variation between manufactured cigarettes and cigarette tobacco was also found.

The mean nicotine content of New Zealand-made regular (filter) manufactured cigarettes tested (19.5 mg per cigarette) was approximately double the reported nicotine content of United States (US) manufactured cigarettes (6-11 mg per cigarette) and Canadian manufactured cigarettes (9-10 mg per cigarette, 1988-93 data). was 19.2 mg per cigarette, double the reported nicotine content of United States (US) cigarettes (6 to 11 mg nicotine per cigarette). North American analyses of the nicotine content of manufactured cigarettes may only include the tobacco in the portion of the stick normally burnt in a smoking test, therefore lowering the apparent nicotine content.

However this difference in analysis technique would only explain a small amount of the difference in nicotine content between New Zealand and North American manufactured cigarettes.

The mean nicotine concentration of the New Zealand regular manufactured cigarettes tested was 2.89%, also higher than that of US manufactured cigarettes (1.6%), and more than double that of Canadian manufactured cigarettes (1.3%, 1993 data).7

The nicotine concentrations reported in this study are by dry weight, whereas at least some of the North American results are concentration by received or 'wet' weight. However, once again, this difference in analysis technique would only explain a small amount of the difference between New Zealand and North American manufactured cigarettes, as there was only about 1 15% difference between concentration by dry and wet weight in our study.

In contrast to our results on nicotine content and concentration, the results of the manufacturers' own smoke yield tests, as stated on tobacco and cigarette packaging, do little to alert New Zealand smokers to the much higher nicotine content and concentration of New Zealand manufactured cigarettes. The sales-weighted average nicotine yield by manufacturers' tests of the smoke from New Zealand manufactured cigarettes in 1996 was 1.2 mg per cigarette whereas the same sales-weight average for US cigarettes in 1993 was just less than 0.9 mg per cigarette.

The nicotine content of New Zealand-made manufactured cigarettes appears to be excessive. Smokers probably need 5 mg of nicotine per day to maintain their addiction. Depending on their method of smoking, smokers absorb 3 to 40 percent of a cigarette's nicotine content. Therefore New Zealand smokers currently need only 1-10 cigarettes daily to maintain addiction whether smoking a regular or mild brand. Given that in 1995 smokers on average consumed 15 manufactured cigarettes per day the nicotine content of New Zealand tobacco could be lowered without compromising the nicotine supply of smokers already addicted.

Lowering nicotine in cigarettes could be expected to lower the addiction risk for those at imminent risk of becoming addicted. For example, young people who temporarily experiment with cigarettes lower in nicotine content may be less likely to become addicted, and former smokers smoking a single cigarette may be less likely to resume smoking permanently. Reduction in nicotine would need to be accompanied by a reduction in tar to prevent current smokers extracting more carcinogenic tar as they maintain their nicotine intake by taking more and deeper puffs. Parliament's Social Services Select Committee recommended that the law should clearly allow regulation of harmful substances in manufactured cigarettes or their smoke. This regulation would include nicotine.

The labelling of cigarettes as 'mild', 'extra mild' or 'super mild' needs to be standardised according to nicotine content or nicotine yield. The current labelling and the colour coding of packets does not allow comparison across brands. One manufacturer's mild cigarette may have a higher nicotine content than another's regular brand. In our study, one extra mild brand had a higher nicotine content than three of the eight regular brand variants tested, and a higher nicotine concentration than five of the regular brand variants tested.

Among the cigarettes tested, we found higher than average nicotine content in the cigarettes which were in packs of 10. Holiday Special Filter 10s had the highest nicotine content of any regular (filter) manufactured cigarette tested, and the highest nicotine concentration of any manufactured cigarette tested. Pack sizes of 10s, 20s and 25s of the Holiday Special Filter brand were tested, and the cheaper brand variants of the cheaper pack size 10s contained the highest nicotine content and concentration. In 1996, this 10 pack size brand variant was the top selling of the cheap brand variants of manufactured cigarettes (December 1996 price of $2.80). Horizon King Size 10s, the other pack sold at this price, also contained above average nicotine content and concentration (Table 1).

In 1996, Parliament's Social Services Select Committee heard evidence that young adolescent smokers most often buy cigarettes in packs of 10. Because of their price appeal to this age group, the Committee recommended that packs of 10 be banned.12