Should you even be using the safety data sheet for a COSHH risk assessment? Consider what is now in the latest ACoP for COSHH.
Paragraph 74 - Where a work activity may expose employees to more than one substance hazardous to health, the employer must consider the possible enhanced harmful effects of combined or sequential exposures.
and
Paragraph 57 - The risk assessment should consider the work activity, including:
all the substances hazardous to health (including biological agents, and simple asphyxiants) arising from the work (used, produced, synthesised, created as waste or by-products, or released from processes or during accidents, incidents and emergencies);
work done by sub-contractors, at the workplace, that may exposure employees to substances hazardous to health.
and
Paragraph 67 - It may be necessary to collect information on the properties and attributes of substances hazardous to health from a variety of sources to fully inform the assessment process
This is further covered in paragraph 35, which states:
When deciding whether the substances used or produced in the workplace are covered by COSHH, employers should also consider the following:
Different forms of a substance may present different hazards, eg substances may not be hazardous in solid form but may be hazardous when ground into fine powder or dust that can be breathed into the lungs.
Nanoparticles (ie particles less than 100 nanometers) may be more toxic than larger particles of the same chemical substance.
Impurities in a substance can make it more hazardous, eg crystalline silica is often present in minerals which would otherwise present little or no hazard.
Some substances have a fibrous form which may present a potentially serious risk to health if the fibres are of a certain size or shape.
Some substances have a known health effect but the mechanism causing it is unknown, eg certain dusts of textile raw materials cause byssinosis.
Exposure to two or more substances at the same time or one after the other may have an added or synergistic effect.
Epidemiological or other data, eg reports of illness due to new and emerging agents, indicate that a biological agent that does not already appear in The Approved List of biological agents could nevertheless cause a hazard to health.
One-off, emergency situations arising out of the work activity, such as a dangerous chemical reaction or fire, could foreseeably produce a substance hazardous to health.
‘Wet work’ is one of the most frequently and consistently reported causes of irritant occupational contact dermatitis. ‘Wet work’ is the term used to describe tasks involving prolonged or frequent contact with water, particularly in combination with soaps and detergents.
On the basis of this I contend that a risk assessment for COSHH has to start with the task, then identify what chemicals are used during the task and what happens to them when they are used. You can then identify the real hazard.
Furthermore, there are thousands of chemicals that have never been assigned a hazard statement but that in use can represent a hazard to health (note the comment in the ACoP on wet work). In his latest edition of his guide to patch testing de Groot lists 4350 substances known to dermatologists as skin sensitiser, only a small fraction of which will ever have been assigned R43/H317.
In my work I see numerous risk assessments based on the safety data sheet that are simple wrong because they have not identified the real hazard.
Chris