Iroko is a tropical hardwood and is covered by EH40- please see the attached link http://www.hse.gov.uk/pubns/wis30.pdf you need to ensure that levels of dust are controlled as with any of the tropical hardwoods (all guidance on HSE website - go to Woodworking on the topics pull down menu and look at the dust control heading) as they have the potential to cause nasal cancers - health surveillance is required.

Thanks for the links they are very useful, the workers will be carrying out general work on this wood and i know hard woods can have sillca and other hazardous substances in them. Thansk again.