Solvent Based Aerosol Hazards

Solvent abuse and SACKI

Solvent abuse by the deliberate inhalation of aerosol paint and other solvent based aerosol products is a serious problem in many countries.

In Europe and the U.K in particular the dangers of solvent abuse is promoted as SACKI -Solvent Abuse Can Kill Instantly' and it is common to see the 'SACKI' logo (Solvent abuse can kill instantly) on aerosol containers. 
http://www.bama.co.uk/volatile_substance_abuse/

It is reported 8 times more people die every year from solvent abuse than from illegal drugs . The inhalation of butane propellant (as part of LPG) can place stress on the heart resulting in irregular heart rhythms. There is a greater risk to the user if they are placed under stress such as being chased.

Solvent abuse, along with graffiti vandalism has meant legislation has been enacted in some parts of Australia to lock up aerosol cans behind shop counters. It is also illegal to sell cans to anyone younger than 18 years old in Australia.

Regardless of these measures there has been pressure placed on aerosol manufacturers in Australia to offer a better solution.

The best solution to combat solvent abuse is to introduce water based aerosol paint to the market however this technology has been difficult to develop for most companies and the final product can be more expensive and can have poorer performance than some solvent base paints.

Aromatic solvents

Aromatic solvents such as Toluene and Xylene are commonly used for fast drying enamels and lacquers such as those used in aerosol paints. Aromatic solvents continue to be used for industrial, Automotive, Marine and heavy duty coatings in many different coatings types including enamel, vinyl, epoxy urethane, Chlorinated rubber and many others.

Toluene and Xylene are some of the cheapest solvent options available for paint, are broadly compatible with most resin types, contribute relatively fast evaporation rates and are readily available. 

'The Narcotic affect'

A characteristic of aromatic solvents when inhaled is the 'narcotic' effect.

Aromatic-free aerosol paints will give a 'high', however it is not as addictive or pleasurable as an aromatic solvent ('narcotic') high. By switching to a solvent other than an aromatic the same attractive (i.e addictive) high is not achieved and it is hoped by aerosol and paint manufacturers there is less attraction for solvent abuse in general. A change in solvent type away from aromatic solvents has been the easiest option technically for paint companies and this change has been made recently in Australia to reduce the attraction for solvent abusers.

Alternatives to aromatic solvents

The choice of solvents for aerosols is very restrictive in that they must be cheap, fast drying, compatible/stable with the resins used, readily available, preferably have a low odor and preferably have a lower toxicity. The first hurdle for an alternative to aromatic solvents is cost as there are few solvents as cheap as aromatics.

Typical alternative solvents to aromatics such as some of the 'oxygenated' solvents like Acetone and alcohols such as Isopropanol can be used. Acetone is relatively cheap and supplies speed of dry. The use of isopropanol enables the coating to flow out after spraying. Careful resin screening is required to ensure thorough compatibility.

Expensive 'lacquer' solvents such as ketones and acetates are used in high levels in nail polish for example where, due to the high sell price the higher costs can be absorbed. The solvent 'high' is generally milder due to the relatively low percentage of aromatic solvent however there is still a 'high' achieved.

THE BEST OPTION FOR ADDRESSING SOLVENT ABUSE IS INTRODUCING WATER BASED AEROSOL PAINT HOWEVER MANUFACTURERS HAVE HAD DIFFICULTY DEVELOPING THE TECHNOLOGY.

OTHER AFFECTS OF USING SOLVENT BASED PRODUCTS

Health 
Peripheral nerve damage, dermatitis, liver and kidney damage are accepted as long term health risks by the medical fraternity.

Environment
Solvent is not a stimulus for organic growth or development. 

Ozone layer
The use of volatile (evaporating) hydrocarbons such as solvents released into the atmosphere does continue to have an an effect.

Petroleum derived products
Some alcohols and oxygenated solvents are produced from organic sources such as sugar however by far the greatest amount of solvents (including LPG/butane/propane propellant) used for coatings , are produced from petroleum feedstock. 

Propellant - the propellant used in water based coatings is the environmentally-friendly Dimethyl Ether (DME) with a half life of only one day in the atmosphere where it quickly decomposes to Carbon dioxide and water.
Most aromatic free aerosols generally still use an unodorised butane/propane blend (ie LPG). Some use DME as it has generally superior solubility but the cost is prohibitive.

Flammability hazards
Spraying a flammable propellant in an an closed area presents the possibility any ignition source can cause a fire or explosion.

Commercial hazards
Storage and shipping of millions of cans presents the possibility that a spill or fire may occur.

Import threats
Overseas companies can all produce aromatic free options cheaper than Australian made product. Local companies may soon be forced to replace locally made product however water based options can give local companies a level playing field and the possibility of jobs generated locally.

Costs
Support of water based aerosol coatings can only help to bring the costs down which can be better for both the manufacturer and consumer.

Options to aromatic solvents in paint are harmful but less addictive

OTHER THAN AROMATIC SOLVENTS IN AEROSOL PAINTS WHAT OTHER SOLVENT OPTIONS ARE THERE?

Some common solvents used in aerosol enamels and lacquers include the following:

'Oxygenated' solvents

• Ketones: e.g acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK)
• Esters: e.g ethyl acetate, butyl acetate
• Alcohols: e.g ethanol, butanol, isopropanol
• Glycol ethers e.g Propylene glycol mono methyl ether acetate (PGMA) 

Aliphatic solvents and propellants

Hexane and Heptane are examples of aliphatic solvents blended with aromatics in thinners such as White spirits and Mineral Turpentine. Aliphatic propellants include blends of (deodorised) butane and propane and liquefied petroleum gas (LPG).

Halogenated solvents

Chlorofluorocarbons (CFC's) and chlorinated solvents such as trichloroethylene and methylene chloride are not used due to their negative impact on the ozone layer. 

AROMATIC FREE FORMULATIONS ARE SAFER FOR AEROSOL CHROMING AND SOLVENT ABUSE BUT HOW MUCH SAFER ARE THEY?

Are the solvent replacements for aromatic solvents any better for the consumers health?

One guide to relative toxicity is the TLV or 'threshhold limit value' and this figure is quoted on Material Safety Data Sheet (MSDS) for products supplied by chemical suppliers and paint companies. Individual chemicals including solvents used in the paint or other finished product are listed in an MSDS and information offered as to the relative toxicities.

The TLV is a relative indication of the concentration of solvent in the air that a person may be exposed to before significant damage can be done to the health. The figure is quoted in either parts per million (ppm) or milligrams per metre cubed mg/m3.

A high TLV means a person may be exposed to a relatively high concentration of solvent before appreciable damage is done, i.e a 'high TLV' solvent is comparatively 'safer' than one with a low TLV. 

There are variations of TLV quoted as can be seen on a Material Safety Data Sheet (MSDS) and these include the TLV-STEL and TLV-TWA.

(TLV-STEL) 
Thresh hold limit value -short term exposure limit. The maximum concentration a person may be exposed to in one dosage 

(TLV-TWA)
Threshold limit value -time weighted average. The average concentration a person may be exposed to in the course of an 8 hour working day.

Some common solvents used in aerosol enamels and lacquers include the following:

CONCLUSION

The move away from an Aromatic such as Toluene with TLV-TWA-mg/m3 (8hr) of 191 mg/m3 to a solvent such as Acetone with TLV-TWA-mg/m3 (8hr) of 1185 mg/m3 means the consumer may be exposed to 5 x more solvent in an aerosol paint before comparable damage occurs.
Relative toxicity is reduced but any solvent exposure including exposure to relatively 'mild' ones such as Acetone can be harmful to health, environment and safety at levels below the TLV.