Some science behind the scenes

Glue and other contact adhesives

Glues contain chemicals such as toluene, ethyl acetate, hexane, acetone, methyl ethyl ketone [butanone] and even formaldehyde.

To understand why,  we perhaps need to define what a glue actually is.  Glue comes as a mixture in a liquid or semi-liquid state.  It adheres or bonds items together by ‘curing’ – hardening  - and it does this in one of two ways: - 

  • either evaporating a solvent - as the solvent evaporates, the adhesive hardens
  • or by chemical reactions that occur between two or more constituents

In effect it is the solvents themselves that are key and their properties in this context.

The problem we have by labelling this area as ‘glue’ is that the chemicals contained in these glues can vary so widely.  The effects are clearly going to be dependent upon the actual chemicals in the glue, as such it is not helpful to say that ‘glue sniffing is harmful’ because although there is a lot of evidence that glue sniffing of all sorts of glues is harmful, it needs more clarification to be believable to those who sniff glue!  

For example, Bostik Wallboard adhesive is a product based almost entirely on toluene.  The glue  is for example,  “Classified as Hazardous according to HSNO in New Zealand.  Classified as a Dangerous Good according to NZS5433:1999 Transport of Dangerous Goods on Land”.  It is described thus “This product contains both volatile (solvents) and non-volatile components. During the normal use of this product, the hazardous volatile components evaporate and dissipate. The remaining non-volatile component is not hazardous”.

Complications of chronic glue (toluene) abuse in adolescents - Devathasan G, Low D, Teoh PC,  Wan SH, Wong PK.

Recently there has been an alarming increase in the number of schoolchildren sniffing glue (toluene). The medical complications seen in 18 boys, aged 14 to 18 years, include physical and mental dependence, pulmonary hypertension with cor pulmonale, restrictive lung defect, encephalopathy, peripheral neuropathy and high frequency, continuous discharges ( neuromyotonia ) on electromyogram. Glue sniffing took place in small groups and abusers sniffed directly from cans containing glue. Lower socio-economic status, overcrowding, lack of attention by working parents, school failure and easy availability of the glue were commonly cited associated factors.

If we now take a look at ‘Liquid Nails’ [note that the correct name is Selley’s Liquid Nails]  It could not be more different.  The volatile chemicals in this product include.
  • Ethylene glycol is an organic compound. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid. Ethylene glycol is toxic, and ingestion can result in death.
  • Formaldehyde is an organic compound with the formula CH2O. It is a colorless gas with a characteristic pungent odour. Exposure to formaldehyde is “a significant consideration for human health”.  On 10 June 2011, the US National Toxicology Program described formaldehyde as "known to be a human carcinogen”
  • Dipropylene glycol is a mixture of three isomeric chemical compounds, 4-oxa-2,6-heptandiol, 2-(2-Hydroxy-propoxy)-propan-1-ol, and 2-(2-Hydroxy-1-methyl-ethoxy)-propan-1-ol. It is a colorless, nearly odorless liquid with a high boiling point and low toxicity.  “Its low toxicity and solvent properties make it an ideal additive for perfumes and skin and hair care products. It is also a common ingredient in commercial fog fluid, used in entertainment industry smoke and haze machines

Inhale the first two chemicals and it could kill you as they are both toxic.

Thus to understand something of the glues and the harm they can do, we need to understand the solvents in them.  For more details see Solvents.