Introduction
So here we are, day 1 of 4 in the countdown to World Cancer Awareness day on the 4th February 2020.
Here on day 1, we bring to you some information about a substance that should be at the forefront of any occupational hygiene or health and safety discussions, and that’s hardwood dust.
In light of the new HSE – EH40/2005 (Workplace Exposure Limits) document revisions released in January 2020, we felt that a discussion around hardwood dust would benefit you, part of our fast-growing audience of health enthusiasts!
In this blog we will be:
Summarising the key health effects of hardwood dust through occupational exposure.
Defining the key routes of exposure when working with hardwood dust from an occupational hygiene and industrial hygiene perspective.
Outlining major processes in which hardwood dust would likely be present.
Evaluating exposures to secondary constituents such as formaldehyde and Paraffin Waxes during mixed composite processing.
This is sure to help responsible health and safety professionals implement new safe systems to help significantly reduce exposures to hardwood. Ultimately, reducing the likelihood of workers contracting work related illnesses through acute and chronic exposures.
Hardwood Explained
Solid Hardwood
Hardwood trees include alder, balsa, beech, hickory, mahogany, maple, oak, teak and walnut. Whereas, softwood trees include Cedar, Douglas Fir, Juniper, Pine, Redwood, Spruce and Yew. Hardwoods have a higher density than most softwoods.
Mixed Hardwood Composites
MDF (Medium Density Fibreboard) is an engineered wood product created by using a breakdown of both hardwood and softwood fibres, which are then combined with a wax and resin binder. Boards are created by applying high temperatures and pressures during the curing process.
Sources of Exposure
Secondary Exposures in Hardwood Processing
The introduction of binding materials such as waxes and resins pose a further risk to health as much of the materials introduced into the process is Formaldehyde and Paraffin Wax. Additional additives may be used to help the wood become moisture resistant and fire retardant. When working with MDF, people need to be mindful of the risks posed by chemical additives such as Formaldehyde, which is in fact a carcinogenic material like hardwood. Another common type of wood composite is also known by the brand Masonite, also known as Quartrboard, Isorel, Hernit, Karlit, Torex, Treerex and Pressboard. We believe this patented method of production involves the steaming of the wood fibres and chippings at high pressures onto boards, forming the end product. This type of process eliminates the use of formaldehyde and any resins or waxes as the lignin naturally joins and forms the boards.
Formaldehyde and Paraffin Wax in Hardwood Composite Materials Pose a Risk of Secondary Exposure
Both formaldehyde and Paraffin Wax have their own workplace exposure limits listed under EH40/2005. Both substances are capable of individually posing risks to health through inhalation. However, in relation to Formaldehyde, as discussed in the International Agency for Research on Cancer (IARC) Monographs on the Evaluation of Carcinogenic Risks to Humans (Volume 62 – Wood Dust and Formaldehyde), the substance has been classified as carcinogenic to humans. Therefore, exposure to MDF or mixed hardwood composite materials poses a high risk to health due to the carcinogenic nature of hardwood and formaldehyde, both present in many MDF of wood composite materials.
Industrial Processing of Hardwood and Mixed Hardwood Composite Materials
Exposures to wood dust can be present across many industries:
Wood Recycling and Biomass
Furniture Making
Vehicle and Camper Conversions
Equestrian Vehicle Manufacturing
Boat Building
Pallet Manufacturing
Wooden Composite Manufacturing and Processing.
Logging and tree cutting
Tree surgery
Horticulture, Agriculture and Farming.
Construction Working and More….
Specifically Identified Carcinogenic Effects
Focusing specifically on hardwood in its original form. That means, without the introduction of glues, binders or composite processing agents, hardwood is classified as a known human carcinogen.
The International Agency for Research on Cancer discuss the types of cancer associated with exposures through epidemiological studies. This is outlined in their IARC Technical Report – Cancer Risk from Occupational Exposure to Wood Dust: A Pooled Analysis of Epidemiological Studies No 30.
Referencing the report, they speak about the predicted excess of Sino-nasal cancer, however further analysis found an excess off nasopharyngeal cancer and haematopoietic cancer. In particular, myeloma. Furthermore, occupational exposure to hardwood dust is causally related to adenocarcinoma of the nasal cavities and paranasal sinuses.
Surprisingly, they stated that no evidence was found for an excess risk of deaths from lung cancer.
Mixed exposures during the processing of wooden composite products poses an increased risk to health due to the carcinogenic nature of Formaldehyde, the substance often used as part of the binding/composite forming process.
In IARC Monograph Volume 88 (2007a), it was concluded that due to the substances association with cancer of the nasopharynx, there was sufficient evidence that formaldehyde was carcinogenic to humans.
Again, wood processing staff are considered at risk of exposure to two carcinogenic substances in hardwood and formaldehyde during the manufacturing of wood composite materials.
Formaldehyde is also found in common adhesives, glues, binders and additives found across industries which assemble and process wooden products.
There are separate health effects associated with exposures to wood processing additives or adhesive based products, of which are beyond the scope of this article.
Health Surveillance
Regular health checks should form part of your company’s health and safety program. We would also suggest that nasal and throat inspections are carried out by a competent occupational health nurse or an on-site doctor. Identifying any abnormalities in the paranasal (spaces in and around the nasal cavity) and nasopharynx (upper part of the throat) is key to ensuring that any potential cancer growths are caught early and that appropriate actions are taken medically to ensure a thorough examination of the individuals suspected of such abnormalities are tested as soon as possible.
The key to ensuring effective treatment is making sure the cancer is caught as early as possible. Therefore, regular health surveillance would significantly increase the chances of identifying any signs of cancer before it becomes more difficult to treat.
Advised Control Measures – Reducing Exposure to Hardwood Dust and Formaldehyde. Helping to Prevent Cancer
Something that will repeat over the course of these 4 days as we evaluate key industries where people may be at risk of getting cancer, is that appropriate controls can minimise exposures and prevent ill health.
Minimising exposures as low as reasonably practicable is a suitable way of ensuring the workers’ health and safety is at the forefront of any business and this can be achieved by implementing elements of the Hierarchy of Control. Of course, you’re a reputable health and safety professional: a health and safety conscious business owner leading from the top: a driven production manager – investing in making sure staff go home healthy and free from harm. So, these pointers will provide “food for thought” whereby the application of the Hierarchy of Control is concerned.
Consider eliminating or substituting the hazard by:
1. Using a material which doesn’t contain hardwood.
2. Using a material which doesn’t contain formaldehyde.
3. Moving onto products processed using less harmful substances as additives. (naturally pressed materials)
4. Automate the process – have the process be carried out in an enclosed CNC.
Install extraction systems:
In the woodworking industry, particularly in furniture making and joinery professions; the use of on-tool extraction is a great way of extracting any contaminant at the source of emission. As occupational hygienists, we do often see this type of local exhaust ventilation (LEV) failing due to poor design of the system.
Enclose machining systems and improve containment by ensuring the enclosure is sealed. Secondary extraction could be applied to the contained system. Any gaps required for in-feeds/out-feeds could be minimised by fitting plastic strips or bristles.
Discourage dry sweeping and instead utilise a suitable vacuum cleaner or wet method of cleaning.
Improve manual handling of wooden boards by training staff to handle with care. Prevent staff from dropping wooden sheets or components, reducing dust plumes on impact.
Provide awareness training with the aim of improving positive behaviour and enhancing a positive health and safety culture within the business.
For help managing your COSHH requirements, please don't hesitate to contact us today for free advice.
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