In 2015 the ACMD considered the emerging issue of nitrous oxide abuse. In 2021, the then Home Secretary commissioned the ACMD to conduct an updated health and social harms assessment and whether nitrous oxide should be controlled under the Misuse of Drugs Act 1971.
On Tuesday 7 February 2023, the Minister of State for Crime, Policing and Fire commissioned the ACMD to expedite this review and provide advice by the end of February 2023.
This new commission sets out the Government’s renewed priority to tackle anti-social behaviour and requests advice on the below social harms associated with nitrous oxide:
- Links between nitrous oxide misuse and antisocial behaviour
- Associated crime and impact on local communities
- Environmental impact, including littering
Submitted by Dr. Plinio Ferreira and Professor Adam Winstock
Social Harms of Nitrous Oxide
Nitrous oxide cream charger cartridges are available to purchase from multiple sources and various online providers such as Amazon who now also provide access to larger canisters (which appear to have little utility within the food industry but may pose a greater risk to those using for intoxication-related purposes). They are also available through online food-specialized websites. In all cases, the buyer needs to be over 18 to do so and suppliers can refuse to sell if they suspect the buyer is underage or has the intent to use it as a recreational drug.
There has been a persistent media campaign for stigmatisation of the use of nitrous oxide since the term “hippy crack” was coined in order to deliberately scare the public and magnify its harms. This has failed to deter use but has to some extent achieved its goal to scare the public that nitrous oxide is more harmful than it is.
Littering with discarded canisters is often one of the most common concerns cited by community members. Compared with alcohol which is responsible for high rates of public disturbance and violence, Nitrous Oxide is a relatively innocuous substance in terms of public disturbance. Littering of nitrous oxide canisters is a well-known problem as the capsules are usually discarded on the floor. It seems to be the greatest concern from the general public since this is a very safe drug if done in moderation.
In regards to contamination, since nitrous oxide is usually inhaled from a balloon, there is negligible if any risk for contamination of blood-borne diseases between users if sharing the balloon. Since the production of food-grade nitrous oxide is regulated such canisters contain a high degree of purity. For some none food-grade nitrous oxide canisters there is a concern about the presence of oils used as coatings or lubricants during the manufacture of cartridges or faults in the canisters themselves.
Nitrous oxide is a potent greenhouse gas however the contribution from recreational use to the depletion of ozone layer is negligible when comparing to other sources. There has also been a steady decline in total annual emissions of nitrogen oxides since 1990 as these have fallen by 76% since 1970.
Nitrous oxide is unlikely to be a substance used to address self-medication of childhood trauma or other distress. The most common drugs used for this purpose are alcohol and other drugs such as opioids.
On a recently published Multi-Criteria Decision Analysis, nitrous oxide was compared to other recreational drugs and a score of 0 to 100 was attributed for 16 different harm criteria. It scored 1 out of 100 for “Loss of Relationships”, 3 out 100 for “Family Adversities”, and 2 out 100 for “Community-related issues”.
For almost 250 years, nitrous oxide has been inhaled for its rapid but short-lived feelings of euphoria, relaxation, calmness and a sense of detachment. In the current behaviour of recreational use, most users inhale small quantities of nitrous oxide occasionally, perhaps one to three balloons in a session, a few times a year. There is also a small, but significant, increase in the number of people who use greater quantities of the gas more frequently and for longer periods of time. It is unclear what dose causes chronic toxicity, although the greater the amount used, the greater the risk. Most cases of poisoning involve regular or heavy use, at least over a few months. A Global Drug Survey study published by Kaar and colleagues noted about 7% of users were concerned over the impact on their physical or mental health and 2% were worried about loss of control. Withdrawal from nitrous has not been reported and in isolation is unlikely to lead people to seek treatment.
While it’s estimated that half a million people used nitrous oxide recreationally in the past year, the National Poisons Information Service received only 36 telephone enquiries about nitrous oxide during that same time. And, according to them, most cases resulted in minor or moderate toxicity. As a comparison, the NPIS received almost 28,000 online access regarding diazepam use and around 13,603 for cocaine. The NPIS is commissioned to provide 24-hour information and advice to NHS healthcare professionals across the UK to support the management of patients with suspected poisoning.
Reports of people driving while using nitrous are an obvious concern and education about the risks of driving under the influence of any mind-altering substance should be reinforced.
Physical Health Harms of Nitrous Oxide
It’s vital to clarify the frequency and intensity of use to answer this question. Most users inhale small quantities of nitrous oxide occasionally, perhaps one to three balloons in a session, a few times a year. This type of consumption behaviour is considered very safe. The Dutch Poison Centre classes ‘heavy use’ as the use of 50 or more balloons in a single session or use from a cylinder, while ‘frequent use’ is classed based on information from the treating physician. Chronic nitrous oxide misuse as defined by Marsden et al (2022) was 15 and 900 bulbs per session over a period of 1 month to 10 years. This type of consumption may implicate health problems.
In an article published on 7th of September of 2002, Prof Nikos Evangelou, a neurologist at the University of Nottingham, writes that before last year (2021) “most of us” – referring to neurologists in the clinical setting – “hardly met a patient with nos-related neuropathy”.
From 1978 until 2016, the average of published clinical cases on Pubmed describing serious harms due to nitrous oxide use was no more than 6 per year. From 2017 to 2021, there has been an increase of these reports and they peaked at 29 on 2021. This coincides with the increased availability of larger cylinders — making the gas significantly cheaper and facilitating broader, more regular and heavier use. It’s also important to note that more interest in nitrous oxide also leads to more cases being published in the literature.
Data available from poison centres in European countries show that in Denmark, cases rose from 16 in 2015 to 62 in 2019, 90 in 2020 and 73 in 2021. In France, 134 cases were reported in 2020 — up from 46 in 2019 and 10 in 2017. Meanwhile, in the Netherlands, cases rose from 13 in 2015 to 128 in 2019, 144 in 2020 and 98 in 2021.
In most cases where chronic toxicity is reported patients present with myeloneuropathy, which resembles the subacute combined degeneration (SCD) of the dorsal columns of the spinal cord seen with classic vitamin B12 deficiency.
In a recent report from the Global Drug Survey, 16,124 participants reported nitrous oxide use in the last 12 months. From these, the number of respondents reporting persistent numbness/tingling (paraesthesia) in their hands or feet was 537 (3.3%). Although the risk was very low among infrequent users, there was a strong dose–response relationship. For people indicating one or two doses per session, the probability of reporting paraesthesia was approximately 0.018 by comparison; for people indicating 100 doses per session, the probability was approximately 0.085. For heavy users that reported 100 doses of nitrous oxide per session, the predicted probability for women reporting paraesthesia was 12.1% (95% CI: 7.16–17.0%) compared with men 7.2% (95% CI: 5.3–9.2%), indicating a difference in gender too.
Deaths involving nitrous oxide are rare. In most cases, the cause is accidental asphyxiation from breathing the gas using a mask or plastic bag over the head without sufficient oxygen. In the UK, according to the Office for National Statistics, between 2001 and 2020, there were 56 registered deaths involving nitrous oxide in England and Wales, with 45 of those having been registered since 2010. A very small amount if compared to the 78,000 deaths attributed to smoking in the UK or 9,641 deaths related to alcohol-specific causes registered in the UK in 2021
Psychological Health Harms of Nitrous Oxide
Nitrous oxide is not defined as a psychoactive substance, as per the 2016 Psychoactive Substances Act, therefore the link between psychological health harms and nitrous oxide consumption is speculative.
The overwhelming majority of recreational users do it occasionally. However, there are anecdotal reports of addiction in the literature. And those with addictive behaviour towards nitrous oxide may suffer from typical symptoms due to drug dependence. Use of other drugs is also common and patients may have a history of mood disorders. It is therefore not always evident that the psychiatric symptoms are attributable to the use of nitrous oxide alone.
There are a few case reports published in the literature describing chronic abuse and dependence, tolerance and withdrawal symptoms.
Promote evidence-based educational programmes in schools with harm reduction concepts being introduced to pupils from a young age, not only for nitrous oxide but for all other recreational drugs, including alcohol and tobacco, aiming to minimise the negative health and social effects associated with drug use. These include: a safe method for dispensing and consuming, health warnings against prolonged and frequent use, advice regarding concomitant use with other recreational substances, and how to act in situations where someone collapses or becomes unresponsive during consumption.
Introduction to health warning labels on canisters or boxes of canisters of nitrous oxide cream chargers as an effort to enhance public awareness of possible hazards that heavy use might lead to.
Restricting the maximum quantity of cartridges or canisters that can be supplied at once.
Restricting commercialization of large volume cylinders (0.6 kg) as these are usually associated with harm and heavy use.
Enforce recycling of used canisters as these are made of steel, keeping the streets and local environment clear of litter. A deposit scheme could be put into place, where there is a financial return if the canister is disposed of in a recycling station. This would be similar to what is already done for plastic and glass bottles.
We, as a group of experts, strongly oppose the classification of nitrous oxide. Given that nitrous oxide is the second most used recreational drug in the UK, with most of its users between the age of 16 and 24, the classification of nitrous oxide would directly lead to the criminalisation of thousands of young people. This action would be harmful, disproportionate and unjustified, creating a huge and expensive burden on an already overstretched criminal justice system, and ineffective as a public health strategy.
This move would create a huge burden of criminal records mainly by young people from socially and economically marginalised communities, which are overexposed to policing, surveillance and stop and search. Criminalisation would also shift the production of nitrous oxide to an unregulated criminal sphere making consumption riskier. As the European drug monitoring agency (the EMCDDA) notes:
‘Restricting supply may lead to the involvement of criminal organisations. This may increase theft and diversion from the legitimate supply chain. It may also lead to homemade or illicit production of nitrous oxide. Methods available on the internet, including do-it-yourself videos, pose a high risk of explosion and contamination with nitrogen oxides, which cause lung toxicity that could be life-threatening’.