COMMITTEES ON TOXICITY, CARCINOGENICITY AND MUTAGENICITY OF
CHEMICALS IN FOOD, CONSUMER PRODUCTS AND THE ENVIRONMENT
(COT, COC and COM)
Introduction
1. The COT, with support from the COC and the COM, was requested to assess
the toxicological risks from novel heat-not-burn tobacco products, and compare
these risks to those from conventional cigarettes.
2. To date, two novel heat-not-burn tobacco products have been notified to PHE
in accordance with the Tobacco and Related Products Regulations 2016.
What are novel heat-not-burn tobacco products?
3. In heat-not-burn tobacco products, processed tobacco is heated in a
controlled device instead of being burnt as is the case for conventional tobacco
products.
4. A recent consultation by HM Treasury1 noted there is a range of heat-not-burn
tobacco products where:
a. processed tobacco is heated directly to produce vapour
b. processed tobacco is designed to be heated in a vaporiser
c. devices produce vapour from non-tobacco sources, where the vapour
is then passed over processed tobacco in order to flavour the vapour
5. The two products assessed by the Committees fall into the first and last of
these groups, and as a result the temperature to which the tobacco is heated varies
considerably between them. For one product where the tobacco is heated directly, a
maximum heating temperature of up to 350 °C was reported, while for the other
product in which the tobacco is heated by a vapour, the maximum temperature of the
tobacco was reported to be less than 50 °C. For comparison, when tobacco in
cigarettes is burnt it reaches temperatures of at least 800 °C.
Information obtained
6. The two manufacturers of products notified in the UK before November 2016
were asked to present the relevant toxicity data they hold. In addition to the
manufacturers’ data, a literature search was undertaken to identify any available
independent data on these products. This was very limited.
Exposure
7. Investigations on both products that were assessed by the Committees,
showed a decrease in the harmful and potentially harmful compounds (HPHCs) to
which the user would be exposed, compared to the HPHCs from a conventional
cigarette2. For both products, there were some HPHCs where the reduction was
approximately 50%, and the reduction in other HPHCs was greater than 90%.
8. The Committees also requested data on additional contaminants from the
devices themselves. The available data presented and discussed with the
manufacturers provided no evidence for exposures other than from compounds also
present in conventional cigarette smoke.
9. The design of the devices means that any potential sidestream emissions
from them will be very different to those from the burning tip of conventional
cigarettes. In terms of environmental exposure to bystanders, assessments showed
that while some of the measured components increased above background with the
use of the heat-not-burn tobacco products, much greater increases occurred
following use of conventional cigarettes.
Toxicity data
10. In compiling the list of information requested by the Committees for this
evaluation, there was a focus on cancer, respiratory, cardiovascular and liver-related
health effects.
Epidemiological data
11. Both products are already available on the market in the UK and other
countries around the world. Post-marketing surveillance is being undertaken by both
manufacturers in these countries, but it is too early for epidemiological information on
health impacts to be available.
Committees’ discussion
A number of differences were identified between the two products notified in the UK, the most obvious being the temperature to which the tobacco is heated, which will potentially have an impact on the number and amount of compounds that thereby become volatile and can be inhaled by the user. There is also a difference in the source of the nicotine. In the product where the tobacco is heated directly, the nicotine is derived from the tobacco in the device, while for the other product the nicotine is present within the liquid that is aerosolised and passed through the tobacco.
13. The Committees were unable to assess the absolute risk of heat-not-burn
tobacco products given the nature of the data available.
14. The data indicated that the aerosol generated from these products contains
HPHCs, some of which are mutagenic and carcinogenic, and therefore there will be
some risk to health from use of these products. The normal recommendation of the
Committees is that exposure to such chemicals is kept as low as reasonably
practicable, but it was recognised that these products could provide harm reduction
for people who would otherwise smoke cigarettes.
15. There would likely be a reduction in risk for conventional smokers deciding to
use heat-not-burn tobacco products instead of smoking cigarettes. However,
stopping smoking entirely would lead to the greater reduction in risk.
16. A reduction in risk would also be experienced by bystanders where smokers
switch to heat-not-burn tobacco products.
17. The Committees were concerned over the potential for non-smokers including
children and young people, who would not otherwise start to smoke cigarettes, to
take up using these products, as they are not without risk. There was also concern
over whether the use of these products would lead to cigarette smoking by nonsmokers. Information on this should be obtained before the overall impact on public
health can be assessed.
18. The data considered by the Committees was not sufficient to comment on the
relative risks of heat-not-burn tobacco products and e-cigarettes, though this is of
interest.
19. The Committees considered the potential risks from use of these products
during pregnancy. The current UK advice3
to pregnant women is to stop smoking
entirely. However, the advice states: “If using an e-cigarette helps you to stop
smoking, it is much safer for you and your baby than continuing to smoke”. There is
no direct data on the risk to the unborn child following use of heat-not-burn tobacco
products by the mother. Based on reduced exposure to compounds of concern with
heat-not-burn tobacco products compared to conventional cigarettes, the
Committees considered that, though the aim should be for pregnant women to stop
smoking entirely, the risk to the unborn baby is likely to be reduced if using these
products during pregnancy instead of smoking.
20. The Committees emphasised that nicotine itself is addictive, and can have
harmful effects on health. In addition, users of any nicotine product would use it in
such a way, and in such quantity, as to achieve a similar effect to that they were
used to from their previous smoking products. Depending on the concentrations of nicotine in different products, relative exposure to other compounds of concern could
be increased or decreased in the process of achieving the desired nicotine effect.
For example a user might take a fewer or greater number of puffs, or use these
products more often or for longer than they did with conventional cigarettes.
Committees’ conclusions.
21. It is well recognised that using tobacco is carcinogenic and its use has other
harmful effects on human health.
22. Using heat-not-burn tobacco products involves breathing in a number of
compounds of concern, some of which are carcinogens.
23. The levels of the different compounds in the aerosol from heat-not-burn
tobacco products are different to the levels in smoke from conventional cigarettes.
24. Heat-not-burn tobacco products contain nicotine and are designed to deliver
similar levels of nicotine to conventional cigarettes; their use will not reduce nicotine
exposure or the risk to health from and possibility of addiction to nicotine.
25. The Committees conclude that there will be a risk to health from using heatnot-burn tobacco products.
26. It is currently not possible to quantify this risk. Heat-not-burn tobacco products
are new and there is insufficient data available to enable a full assessment.
27. The exposure to compounds of concern in using heat-not-burn tobacco
products is reduced compared to that from conventional cigarette smoke. It is likely
that there is a reduction in overall risk to health for conventional smokers who switch
to heat-not-burn tobacco products.
28. While the Committees conclude there is a likely reduction in risk for smokers
switching to heat-not-burn tobacco products, a risk remains and it would be more
beneficial for smokers to quit smoking entirely.
29. A reduction in risk would be expected to be experienced by bystanders where
smokers switch to heat-not-burn tobacco products.
30. The risk to the unborn child from use of these products by mothers during
pregnancy is difficult to quantify and current NHS advice is to stop smoking entirely.
The Committees consider that the risk to the unborn baby is likely to be reduced if
these products were used during pregnancy instead of smoking, although the aim
should be to stop smoking entirely.
31. Overall, the Committees conclude there are toxicological risks from novel
heat-not-burn tobacco products though data on impacts to human health is very
limited. Compared with the known risks from conventional cigarettes, they are
probably less harmful. Even so, smokers would do better to quit entirely.
COT, COC and COM
COT 2017/04; December 2017