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End uses of formaldehyde products
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- Measured exposure data
End uses of formaldehyde products
Information from industry submissions indicates that most of the formaldehyde resins used in Australia contain < 0.2% free formaldehyde. However, some contain up to 13% free formaldehyde. In addition, formaldehyde gas can be released if resin is heated to temperatures where it decomposes or when in contact with high humidity levels. Information from the Plywood Association of Australia (PAA) indicates that approximately 500 operative staff work in the processes of glue mixing, glue spreading, panel lay-up and pressing. These workers are potentially exposed to formaldehyde-containing adhesives used in plywood mills. No information is available on the total number of workers handling formaldehyde resins in the manufacture of particleboard and MDF. The concentrations of free formaldehyde in the resins used in particleboard and MDF manufacture range from < 0.2% to 0.5% and are up to 5% in the plywood industry. During particleboard and MDF manufacture, operators are likely to be exposed to formaldehyde from the hot press procedure and onwards (see Figure 7.5), as the formaldehyde resins are handled in enclosed systems in the processes before the hot press. However, potential exposure could occur in situations where there is a need to break open or enter the enclosed system, such as equipment cleaning and maintenance. Typically, filters in the resin storage tanks are cleaned manually 1 to 2 times per shift and the task takes about 10 minutes each time. The storage tanks are cleaned yearly for melamine urea formaldehyde resin and once in 3 to 4 years for urea formaldehyde resin. These pressed wood products are used industrially in furniture and cabinet making and also have do-it-yourself (DIY) applications. The atmosphere created by machining the products, such as fitting, sawing/cutting and sanding, contains a mixture of wood dusts, free formaldehyde, dust particles onto which formaldehyde is absorbed and, potentially, the resin binder itself and derivatives. Therefore, workers are likely to inhale airborne formaldehyde. The use process of formaldehyde resins in other industries (Section 7.3.3) involves basically dilution and/or mixing with other ingredients and then a drying process to make the resin set. Some uses, such as paper treating and coating, also involve hot pressing after drying. The methods of application of the resin product vary largely and include dipping/bathing (paper treating and coating, textile finishing and leather tanning), brushing (composite construction), spraying (fibreglass industry and anti-graffiti wall sealer manufacture), use of mop/bristle rollers, and use of mechanical equipment, such as print screen and dyeing machines in textile printing and dyeing. The duration of use varies from a couple of minutes per day to continuous use. Information on the total number of workers in these industries is not available. Information from industry submissions and the NICNAS survey indicates that half the number of companies using formaldehyde resins or products containing formaldehyde resins have local or roof exhaust ventilation in place. Others rely on general ventilation. Basic PPE (gloves, safety glasses and clothing) is worn at most sites during handling of formaldehyde resin products. Some reported use of respiratory protection during glue mixing. One company using formaldehyde resin in making hardboards reported that it does not use any PPE. In summary, workers’ exposure to formaldehyde during use of the resin is likely to be higher if the resin contains high levels of free formaldehyde, especially by inhalation during the hot press process. Skin exposure is also possible during use of the resin in a variety of industries due to the manual handling involved and the high viscosity of some adhesive resins. Measured exposure dataMonitoring data (1999-2004) at pressed wood manufacturing sites were provided by PAA and AWPA, and are summarised in Table 15.4. In plywood mills, most long-term personal monitoring results (61/71) were < 0.3 ppm. No short-term personal monitoring data was provided. Most of the long- term static data (31/34) showed levels < 0.3 ppm. It appears that formaldehyde levels are higher at mills using urea formaldehyde resin. In particleboard and MDF mills, limited data showed that most of long-term samples were < 0.3 ppm (5/8 for personal samples, 12/17 for static samples). No short-term data was available. AWPA has an air monitoring program in place for wood working companies in VIC, NSW and QLD which use the wood panel products manufactured by its members. The data in 2001-2003 were provided and are summarised in Table 15.4. The majority of personal samples (154 out of 159) showed formaldehyde levels < 0.2 ppm in workers’ breathing zones. A limited number of companies using formaldehyde resins in non-wood working industries provided air monitoring data and the details are also shown in Table 15.4. Long-term personal sampling during core making indicated that most samples (13/17) were >0.3 ppm. It was noted that the formaldehyde levels reduced significantly after process modification. Static levels of up to 0.5 ppm were measured in coater rooms using paints containing formaldehyde, whereas 16 static samples in the firelighter manufacturing site were all < 0.5 ppm (the limit of detection).
1.7 ppm). However, some high levels of formaldehyde (2 ppm to 7.4 ppm) were measured in wood and paper industries, mainly during glue preparation, hot pressing, sawing, and paper impregnation with formaldehyde resins. 158 Priority Existing Chemical Assessment Report No. 28 Table 15.4: Summary of Australian monitoring data during manufacture and use of some formaldehyde resin products
3 >0.3-0.5 2 >0.5-2
Table 15.4: Summary of Australian monitoring data during manufacture and use of some formaldehyde resin products (continued) NR, not reported; NIOSH, National Institute for Occupational Safety and Health; AS, Australian Standard; MDF, medium density fibreboard; PAA, Plywood Association of Australasia; AWPA, Australian Wood Panel Association. # The results are presented as the number of samples in a series of result bands where necessary.
Table 15.5: Summary of overseas monitoring data during use of some formaldehyde resin products
abrasive materials in 24 workplaces Plywood mill personal 22 Dryers, composers, during pressing and finishing process
Plywood manufacturing in a New Zealand mill static 10 Dryers, composers, during pressing and finishing process 7.5-19 h NR 10 <0.1 PAA (measured in 2004)
Use of PF glue (<0.4% free FA) in plywood mill personal 49 Patching/machine feeding/forklift driving/scaring/assembly/hot pressing/glue preparation/finishing/carrying plywood piles 8 h air sampling pumps and HPLC 26 ≤0.1
19 >0.1-0.2 4 >0.2-0.3 Makinen & Kangas, 1999
static 74 areas where glue was directly used (13 sites) 8 h 21 ≤0.1 33 >0.1-0.2 14 >0.2-0.3 6 >0.3-0.5 Machining MDF - sawing and sanding static 48 Work room 30 min. Kitagawa 710 tubes 0.01-0.10 Chung et al. 2000 48 Working bench 30 min. impregnated filters 0.02-0.14
Carpentry workshop static 4 Not indicated > 3 days Passive sampler method and HPLC
0.03-0.06 Gillett et al. (2000) Glue/paint used in graphics static 4 Not indicated > 3 days 0.04-0.06 Gillett et al. (2000) Sand foundry and static die-casting foundry personal 46 moulding/core making/pouring/shake-out/static die- casting/core knock-out 8 h diffusive samplers and GC 0.007-0.12 Westberg et al., 2001 static 20 NR 8 h 0.007-0.12 NR, not reported; MSD, mass-selective detection; HPLC, high performance liquid chromatography; GC, gas chromagraphic; FA, formaldehyde; PF, phenol formaldehyde; MDF, medium density fibreboard; NIOSH, National Institute for Occupational Safety and Health; PAA, Plywood Association of Australasia. # The results are presented as the number of samples in a series of result bands.
In 1997, UK HSE initiated a review on the health effects of exposures arising from machining MDF. As part of the review, HSE carried out a hazard assessment and an exposure survey and researched the characteristics of MDF dust including formaldehyde. The published document (UK HSE, 1999) summarised a number of human cross-sectional studies published in 1988 to 1994 where the majority of these measured free formaldehyde levels (both static and personal sampling) at workplaces using wood panel products. The average formaldehyde level within workers’ breathing zone ranged from < 0.01 ppm to 0.4 ppm, with peak level up to 0.8 ppm. The apparent decrease in the formaldehyde levels over the years may be attributed to the reduced level of free formaldehyde in resins and improvements in processes and control measures.Forensic/hospital mortuaries and pathology laboratories
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