Using Dichloromethane?
June 1st 2004

Dichloromethane is a carcinogenic, toxic chemical, that can still be found in many industrial products. Graham Stevens, of Stevens Industrial Services explains the problems surrounding the use of this chemical.

Many people in industry still unknowingly work with products that can potentially damage their health. Often this is due to the ignorance of employers and consequently their failure to look for safer alternatives.

Regulations have been put into place to ensure that employers take appropriate action over the exposure of hazardous chemicals. For example, the Control of Substances Hazardous to Health Regulations 2002 (COSHH) outlines procedures and precautions, that help safeguard the employee's health and safety. Step three of the COSHH requirements states that 'you must prevent employees being exposed to hazardous substances', in cases that are reasonably practical. In the case of dichloromethane, this is not happening.

Dichloromethane or methylene chloride is a particularly dangerous solvent. Apart from being proven to cause damage to the blood, the nervous system, the liver, the eyes and the skin, if used long-term, dichloromethane can cause cancer. In 2003, the Chemical Hazard Information and Packaging (CHIP) Regulations, named dichloromethane a category three carcinogen risk phase 40. Under CHIP, any products containing dichloromethane must be labelled with the warning 'limited evidence of carcinogenic effect'. The labelling must also state that it is harmful by inhalation, swallowing and contact with the skin. But, despite the COSHH and CHIP regulations, use of products containing dichloromethane continues.

Uses of this colourless organic solvent, that has a sweet, chloroform-like odour, include its contribution to cleaning agents in a variety of industries, a fumigant for strawberries and grains, extracting substances from foodstuffs and in weld spatter control products.

In the case of welding, anti-spatter sprays containing dichloromethane have been a popular choice because they are cheap and effective. However, in welding applications, the risks of this chemical are further increased. As a chlorinated solvent, dichloromethane treatments, if still wet at the time of the weld, thermally decompose to give off phosgene (mustard gas) and hydrogen chloride (which burns). A measure of the hazard imposed here is that the HSE gives a short term exposure limit (STEL) of 15 minutes in the presence of just 0.06 parts per million (that is 0.000006%) of phosgene and 5ppm (0.0005%) of hydrogen chloride. Yet dichloromethane based anti-spatter treatments were once commonly used when welding inside pressure vessels. Up until recently non-dichloromethane based products did not work as effectively, hence the dangerous anti-spatter treatments are still being used.

Fortunately, the market now offers effective, dichloromethane free spatter control products such as Pre-Weld anti-spatter spray, that has proven to be highly effective and safe to use. Pre-Weld is made from a blend of highly refined vegetable oils and most of the major car manufacturing plants and fabrication companies in the UK are now using this product.

However, recent findings from a survey carried out on behalf of Stevens Industrial Services, show that many end users remain uninformed about dichloromethane. The survey revealed that 35% of welders who use anti-spatter treatments are unaware of the fact that dichloromethane damages health. If suppliers fail to inform distributors of the harmful side affects of these products, they, in turn will fail to inform the end users. It is these end users who, without realising, put their own health at risk. Of the 65% of welders who do realise the health and safety implications of dichloromethane, 50% have subsequently stopped using products containing this. Perhaps most shocking, though, is that 32.5% of welders, who use anti-spatter treatments, are aware of its health and safety implications yet continue to use it.

If dichloromethane's use cannot be completely prevented, then employers must ensure staff are kitted out with protective clothing and eye wear because, as a defatting agent, its exposure causes irritation to the skin and eyes. Ventilation must also be adequate and levels of dichloromethane in the air controlled to below the maximum exposure limit of 100 parts per million. The best option employers have is to eliminate the use of dichloromethane altogether. Taking appropriate action is vital, if only to safeguard themselves. Compensation is already crippling companies in the US and Britain is following suit. In 2002, the UK's compensation pay out bill was 10bn. The potential for claims against employers allowing employees to use dichloromethane based products and similarly dangerous chemicals is going to be huge. There is no known insurance company that will provide liability insurance against the use or sale of any product that has 'dichloromethane' or 'carcinogenic' on the label. Conscientious employers should not need to worry about the threat of litigation. As long as they take necessary precautions or eliminate the use of dichloromethane, they will achieve a healthier and more productive workforce.