Reed diffusers: a potential cause of poisoning in young children in New Zealand

There are a wide range of consumer products in the household environment that can result in poisoning of young children through exploratory behaviour.

Reed diffusers are a variety of air freshener, used to broadcast fragrance into a living or working space. The diffusers include a reservoir containing a fragrant solution and a series of “wicks”, made of rattan, bamboo or similar, to draw up the fragrant solution and passively release it into the air. Reed diffuser solutions have been reported to be composed of a solvent, typically glycol ethers and/or ethanol (70–90%), with smaller amounts of fragrance/essential oils (10–30%) and other proprietary fragrances or additives.¹

While toxicology will differ between the various glycol ethers, effects on the kidneys and liver and depression of the central nervous system (CNS) appear to be common toxicological features, although effects on the liver and kidney have only been noted in repeated dose studies.^2,3 A wide range of essential oils are likely to be used in reed diffuser fluids, with human toxicological information available for a relatively narrow range of these oils. While it is difficult to make any general statements about the toxicity of these materials, CNS depression, seizures and liver effects have been reported.^4–8 Effects have been seen following ingestion of less than 10mL of essential oil,^7–10 suggesting that ingestion of as little as 20mL of a reed diffuser fluid containing 30% essential oils may be sufficient to cause adverse effects.

Exposure to reed diffuser fluids is most likely to be due to exploratory behaviour by young children. This is consistent with available surveillance data. Information from a British study suggests that the majority of incidents (94%) involved children under the age of 5 years and, in the 13% of cases where ingested volumes were reported, the median amount ingested was 20mL (interquartile range 10–40mL).¹

While no appropriate acute toxicological studies were identified to provide suitable exposure reference points, case reports of ingestion of glycol ethers or essential oils suggest that exposure to these substances during ingestion of reed diffuser fluid could be at levels where adverse effects would be expected. However, the British study mentioned above found that 80% of cases were asymptomatic and none exhibited severe symptoms.¹ Most cases reported suggest that adverse health effects as a result of ingestion will resolve.^4–8

In New Zealand, during the 2019 year, of 29 notifications to the Hazardous Substances Disease and Injury Reporting Tool (HSDIRT) for people 19 years or younger, four (14%) related to ingestion of liquid from reed diffusers or essential/fragrance oils from another source (in email from Shunnie Xie, Environmental Health Indicators Programme, Massey University, on 29 July 2020). All four notifications were for children aged 0–4 years. Also during 2019, the New Zealand National Poisons Centre (NPC) advised on the management of 94 patients exposed to the contents of a reed diffuser (in email from Dr Adam Pomerleau, Director, National Poisons Centre, on 16 November 2020). Additionally, advice was provided to 13 patients who were exposed to a diffuser oil in an unspecified container, and 173 patients with exposures to essential oils. Of the 94 known reed diffuser exposures, 77 (82%) involved children aged 0–2, 85 (90%) were due to age-appropriate child exploratory behaviour and 20 (21%) were advised to be medically assessed. A further 600 calls to the NPC were reported during the period 2019–2024, suggesting that this issue persists.¹¹

Controlling risks associated with ingestion of reed diffuser fluid is complicated by the fact than many of the products are used as an open container and often sit within easy reach of young children. A recent survey by Consumer NZ highlighted that reed diffuser products are sold with relatively little or no information on the composition of the fluid or information on any associated hazards or safety warnings on labels.¹¹ Control of risks is likely to be best achieved by increasing consumer awareness and the Consumer NZ article includes useful advice, such as keeping reed diffusers out of the reach of children.