Contracts should be placed before work begins. If this is impossible, then essential safety matters must be agreed in writing. The Producer is responsible for the proper documentation of contractual arrangements with outside organisations or individuals. Self-employed people carry the responsibilities of employer and employee, as appropriate. Although that has happened, it is extremely unusual.
Hazard is the inherent ability to cause harm.
Particular Risk . There are some people who are at 'particular risk' from some hazards. Someone with asthma may be at more risk from a respiratory irritant. Someone with a leg in a cast may have difficulty getting about, and be unable to sit comfortably at a work station. Those with special needs e.g. impaired sight, hearing or mobility.