Historically, a number of coating powders have contained substances which were considered to be carcinogenic, mutagenic, toxic for reproduction or asthmagenic. These were typically in the curing/hardening agents or in specific pigments. Whilst the manufacture of powders containing these substances has all but disappeared in the UK and Europe, there may still be old stock available for use or potentially being imported from outside Europe. Exposure occurs by breathing in dust containing these substances, by skin contact and by ingestion. Ingestion can result from contamination of hands, food, drink etc.
List of substances of concern and their health effects classification
- TGIC (triglycidlisocyanurate)– Category 1B mutage
- Lead sulfochromate yellow – Category 1B carcinogen and Category 1A reproductive toxin
- Lead chromate molybdate sulphate red – Category 1B carcinogen and Category 1A reproductive toxin
- TMA (tri-mellitic anhydride) – asthmagen
Additionally, there may also be some direct irritant effects from these substances on contact with the skin, eyes and lungs.
The first three substances above are subject to action under the Registration, Evaluation and Authorisation of Chemicals (REACH) regulation. An application has been made for 'authorisation' for the two pigments (substances 2 & 3 above) to allow continued use (although no decision has yet been made – May 2015). TGIC has been added to a 'candidate' list of SVHC's which will lead to the same process of authorisation in due course. It is estimated that application for authorisation for continued use of TGIC will be needed around 2017-18. See REACH Webpages for more information.
Occupational exposure limits
TGIC has a Workplace Exposure Limit (WEL) that requires exposure to be as low as is reasonably practicable below 0.1 mg/m3 (8-hour time-weighted average(TWA) exposure).
TMA has both an 8-hour TWA WEL and a short term exposure limit (STEL) that requires exposure to be kept as low as reasonably practicable (ALARP) below these limits. These WELs are 0.04 mg/m3 for the 8-hour TWA WEL, and 0.12 mg/m3 for the STEL.
Both pigments listed as 2 & 3 above do not have statutory exposure limits but as both are carcinogens, exposure should be controlled to ALARP principles.
The first consideration should always be to avoid using these hazardous powders.
What should users of coating powders containing these substances do?
a) Assess the risks created by any work liable to expose any employee to the above (or similar) substances. This includes exposures during maintenance and cleaning activities. The assessment should identify the steps necessary to ensure that exposure is controlled to ALARP principles.
b) Prevent employees' exposure to all substances hazardous to health, including coating powders containing these substances. This is required by the Control of Substances Hazardous to Health COSHH) Regulations.
Employers can comply with this requirement by completely eliminating the use of powders containing these four substances.
They should, therefore, check whether use of a coating powder containing these substances is really necessary. If the object to be coated is for indoor use, a specialist polyester powder may not be required. Where polyester coatings are essential, alternative powders may be available. The ability of any alternative to do the job and the potential health risks associated with it should be properly assessed before any handling or use. Coating powder suppliers should be able to give information. See Substance substitution - COSHH
Where a substitute powder is not reasonably practicable, check that all necessary control measures are being taken. Consider all work activities where exposure may occur, for example during the loading of feed hoppers, applications of powders, cleaning of spray booths, spillage clearance, and powder recovery. Wherever possible, totally enclose the work activity.
c) Apply all the control measures listed in Employer information webpages that may be appropriate. Any RPE provided as a last resort should be of an APF of at least 40.
Air sampling (or other exposure monitoring) is required where necessary to ensure the maintenance of adequate control of these substances and to establish exposure levels. This shall be carried out in accordance with a suitable procedure. The air monitoring method for TGIC is published in HSE guidance MDHS85.
Where exposure is not significant, monitoring regimes can be adjusted accordingly. Remember that the health hazards may apply both from inhalation and skin contact, so air sampling may not provide a complete picture of the exposure risks.
The results of an individual's exposure monitoring should be discussed with that individual. Where elevated levels are present, their exposure should be investigated to determine where controls have failed and what can be done (both by the company and the individual) to minimise exposures.
Where monitoring relates (or can be related) to an individual's exposure, that record should be kept for 40 years. Other monitoring records should be kept for at least five years.
See HSE's webpages for more information on health surveillance.
Where these substances present a risk of skin sensitisation – you will need skin surveillance, see COSHH Essentials Sheet G403.
This is a requirement of Regulation 11 of COSHH and further information is given in HSE Guidance Note MS24 - Medical aspects of occupational skin disease.