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Priority Existing Chemical Assessment Reports - Triglycidylisocyanurate (TGIC)
Introduction The chemical known as triglycidylisocyanurate (TGIC), CAS No. 2451-62-9, was declared by the Minister for Industrial Relations as a priority existing chemical (PEC) by notice in the Chemical Gazette of November 5, 1991.
TGIC is a triepoxy compound used as a cross-linking agent. The declaration was to apply in general with no limitation as to specified purpose or geographical area. The main use for TGIC in Australia is as an ingredient of powder coatings used in the metal finishing industry.
The declaration by the Minister was made on the basis that there were reasonable grounds for believing that handling, storage, use and disposal of the chemical could give rise to a risk of adverse health effects.
In summary these grounds were:
The objectives of the assessment were to:
In order to meet the assessment objectives, information was collected from a range of sources, including the information dossiers documenting toxicology, manufacturing and data relevant to occupational exposure obtained from applicants, a literature search and site visits.
Following declaration of TGIC as a PEC, importers and manufacturers were required to apply for assessment of the chemical. The applications received indicate that while there is significant importation of TGIC and TGIC powder coatings, there is no intention to manufacture TGIC in Australia. This report therefore focuses on the use of TGIC in the manufacture of powder coatings for metal finishing and in the application of powder coatings to metal objects.
Background TGIC has been used as a curing agent in weather-resistant powder coatings in Europe for about 20 years. For much of this time TGIC powder coatings have also been in use in Australia, either imported or manufactured by ICI Dulux Pty Ltd, Taubmans Pty Ltd or Paint Industries Pty Ltd. Powder coated objects are now ubiquitous in Australia, and include office and garden steel furniture, car parts, metal fencing, window and door frames, domestic appliances such as refrigerators, washing machines and ovens, shelving and electrical equipment.
TGIC contains three epoxide groups which give alkylating and cross-linking properties to the chemical. There are two main technical grades of TGIC used in the manufacture of powder coatings world-wide. These are Araldite PT 810, also known as TK 10622, manufactured by Ciba-Geigy Pty Ltd in Europe and TEPIC manufactured by Nissan Chemical Industries Pty Ltd in Japan.
During the manufacture and use of TGIC over the last 20 years the only human health effect reported in the literature is allergic dermatitis. In the unpublished and published literature there is a range of animal toxicological studies available.
In 1991, inhalational studies in animals raised concerns that TGIC may be genotoxic at low dose levels, and may therefore act as either a reproductive toxicant, an inducer of heritable mutations and/or a carcinogen in humans. This report assesses the data and makes recommendations on safe use of TGIC and products containing it.
Applicants
Chemical Identity Chemical name: Triglycidylisocyanurate Chemical Abstracts Service (CAS) Registry No. 2451-62-9 Other names:
Trade names: Araldite PT 810; TEPIC; TK 10622 Molecular formula: C12H15N3O6 Molecular weight: 297.3 Physical And Chemical Properties TGIC is manufactured and supplied as the technical grades TEPIC and Araldite PT 810 (also known as TK 10622). The physical and chemical properties listed below are those of the technical grades. Degree of purity TEPIC approx. 90% TGIC; Araldite PT 810 > 97% TGIC. Appearance: At 20°C and 101.3 kPa, the TGIC technical grades are white, granular solids with no discernible odour. Melting Point: 90-125oC (TEPIC), 95oC (Araldite PT 810). Density: 1420 kg/m3 (TEPIC), 1460 kg/m3 (Araldite PT 810). Vapour Pressure: 7.2 micro.Pa at 20°C (Araldite PT 810). Water Solubility: 9 g/L at 25oC (TEPIC). Partition Co-efficient: log Po/w -0.8 (TEPIC). Hydrolysis as a function of pH: TEPIC has a half-life of approximately 1.25 hr at 70oC in aqueous solution. Araldite PT 810 is not hydrolysed at pH 7 in 3 hr or at pH 2 in 1 hr and it has a half-life of approximately 40 minutes at pH 1, at 37oC. Dissociation Constant: Not applicable as TGIC contains no dissociable groups. Flash Point: > 170oC (TEPIC). Combustion Products: CO2, CO, oxides of nitrogen. Autoignition Temperature: > 200oC (TEPIC) . Reactivity/Stability: Molten TGIC reacts rapidly with the following functionalities - primary and secondary amines, carboxylic acids and anhydrides, thiols, phenols and alcohols (the last at higher temperatures). It can also be polymerised by catalysts. Molten TGIC may undergo hazardous autopolymerisation. Particle size distribution: TEPIC = 0.003% < 10 micro.m, 0.12% < 150 micro.m, 99.6% > 400 micro.m. Powder coating (a) = 99.7% < 105 micro.m, 6.2% < 9.56 micro.m, 2.3% < 7 micro.m. Powder coating (b) = 96% < 106 micro.m, 4.0% < 9.4 micro.m, 1.0% < 6.6 micro.m. Use TGIC is used as a 3-dimensional cross-linking or curing agent for polyester resins. The powder coatings are sprayed onto metal objects by an electrostatic process. The spray guns charge the powder with a positive or negative charge depending on the spray equipment used. The electrostatically charged powder particles are sprayed onto earthed metal objects. The metal objects are then placed in a stoving oven where at temperatures of approximately 200oC the resin melts, flows and chemically cross-links to form a durable paint film. The powder coated articles are allowed to cool prior to inspection, packing and despatch. TGIC is not manufactured in Australia. The estimated amount of TGIC, imported as technical grade and as a component of powder coatings, is 100 to 1000 tonnes per year. Manufacture Of TGIC Powder Coatings Technical grades of TGIC are imported into Australia as granules. In the manufacture of powder coatings, TGIC granules are mixed with resin, pigments, fillers and additives at a level of between 4 and 10% by weight of the final product. Pigmented powder coatings usually contain between 4 and 5% of TGIC. Clear powder coatings do not include pigments and contain between 7 and 10% TGIC. The estimated ratio of pigmented powder coatings to clear powder coatings used in Australia is in the order of 100 to 1. The raw materials, including TGIC in granulate form, are weighed into a mixing hopper. Batched raw materials are dry blended in a sealed mixer and then transferred to an extruder where initially the mixture is heated until melting occurs (>100°C). This melt is mixed to ensure homogeneity and is then extruded onto a roller which spreads the extrudate out into a thin sheet. The sheet is carried on a conveyor belt where it cools and solidifies. The solid material is then automatically chipped, milled and sieved to remove coarse particles. The resulting fine powder is packed into polythene bags which are placed in cardboard boxes and finally despatched to customers. In the resultant powder coating, TGIC is partially cross-linked to the polyester resin. Human Health Effects Available data on the effects of TGIC exposure in humans are limited to three published case reports, some health effects data from ICI Dulux Australia and results of a survey of spray painting workplaces using TGIC powder coatings conducted by New South Wales WorkCover Authority. The only human health effect reported in the literature is allergic dermatitis in workers exposed to TGIC or TGIC powder coatings. In the case reports, three workers developed allergic dermatitis on exposure to TGIC or TGIC powder coatings and these workers tested positive with TGIC patch testing. A summary of the health status of workers in an Australian plant formulating TGIC powder coatings was provided by ICI Dulux. In 1991, twenty-eight employees underwent medical examinations. Respiratory effects were present or reported in 5 employees and irritant effects in 8 employees. Irritant effects included nasal, eye and throat irritation, skin rash and nose bleeds. The report stated that stricter controls were implemented which resulted in the elimination of occupational health effects among employees. In 1992/93, NSW WorkCover Authority conducted an inspection of workplaces in Sydney using TGIC powder coatings. Spray painters were asked about the health effects they had suffered as a result of using TGIC powder coatings. The workplaces first aid and compensation records were also examined by the WorkCover inspectors. The survey indicated that 11 of the 232 spray painters had experienced adverse health effects, mostly skin rashes, as a result of using TGIC powdered coatings. Assessment Of Animal Toxicological Data Acute animal toxicity studies showed that for TGIC the oral LD50 for male rats is < 100 mg/kg and for female rats the LD50 is 255 mg/kg. In the acute oral studies the LD50 values were variable but this may be due, in part, to the different vehicles used for the test substance. The dermal LD50 for rats is > 2000 mg/kg. The acute inhalational LC50 of TGIC in female rats is 650 mg/m3 and in male rats is > 650 mg/m3. No deaths occurred in the male rats exposed to the dose level of 650 mg/m3. The results of short term repeated dose studies with TGIC indicated that, other than at the site of administration, the major effects were lung, gastric/duodenal and renal damage. TGIC presents a risk of serious eye damage in rabbits. It is not a skin irritant in rabbits and is positive as a skin sensitiser in guinea pigs. TGIC was shown to be positive in a number of in vitro and in vivo genotoxicity tests. In in vitro studies, TGIC did not induce chromosomal aberrations or unscheduled DNA synthesis (UDS) in human lymphocytes or fibroblasts respectively, but was able to induce UDS in isolated rat hepatocytes. TGIC induced mutations in Salmonella typhimurium (Ames test) and mouse lymphoma cells but was unable to induce cell transformation in mouse embryo fibroblasts. TGIC was not a potent mutagen in the Ames test. Other studies published in the literature demonstrated positive in vitro tests for induction of sister chromatid exchanges (SCEs) and chromosomal aberrations using Chinese hamster ovary cells and Chinese hamster lung cells. In one study, a reduction in the response to treatment was noted when metabolic activation was present. A similar effect was noted in the mouse lymphoma mutagenicity test. The results of in vivo studies indicate that TGIC is genotoxic. A number of studies using oral administration of TGIC have been conducted. Induction of nuclear anomalies and SCEs were demonstrated in the Chinese hamster, indicating that TGIC has genotoxic effects on somatic cells in vivo. Similar effects on germ cells were also demonstrated by the induction of chromosomal aberrations in mouse spermatogonia together with marked cytotoxicity, following oral administration of TGIC. Another chromosomal aberration study, using lower dose levels of TGIC, was negative in mouse spermatocytes. A positive dominant lethal effect was observed at only one dose point in one of two oral experiments, and the results were considered equivocal. Results of in vivo mutagenicity studies following inhalational exposure to TGIC were inconclusive. In a whole body inhalational study, the clastogenic potential of TGIC could not be determined because of the study's shortcomings. In this chromosomal aberration study, there appeared to be a high level of cytotoxicity caused by TGIC in the mouse spermatogonial cells at doses of 10 and 50 mg/m3. However, it was possible that the low number of cells was due technical error. In a similar, repeated dose toxicity study, using inhalation nose-only exposure to TGIC, cytotoxicity was not observed at dose levels of up to 140 mg/m3. In a more recent report, both nose-only inhalational and oral administration of TGIC were studied. Only one dose of TGIC was administered by inhalation, 7.8 mg/m3, and there were no signs of cytotoxicity, adverse clinical effects or induction of chromosomal aberrations. Oral administration of 115 mg/kg TGIC did induce chromosomal aberrations and cytotoxicity. The clastogenic potential of TGIC, as a result of inhalational exposure, could not be determined in this study because a dose response relationship was not studied and at the dose level chosen neither cytotoxicity nor adverse clinical effects were observed. Of two studies of dominant lethal effeccts using inhalation exposure, no dominantt lethal effects were observed but one study did show reproductive toxicity at 50mg/m3. The results of a mouse spot test following intraperitoneal administration of TGIC were negative. The molecular structure of TGIC indicates a potential for alkylating DNA. This was confirmed in a study where DNA-binding of 14C-TGIC was measured in stomach, liver and testis DNA following oral administration in mice. Three hours after administration the ratio of TGIC-DNA adducts in stomach, liver and testis DNA was about 30:6.5:1. In a recent study TGIC was shown to bind to DNA in rat livers in vivo following oral and intraperitoneal administration. Induction of liver microsomal epoxide hydrolase activity was associated with increased hydrolysis of TGIC and a corresponding decrease in TGIC-DNA adduct formation. The microsomal epoxide hydrolase activity was measured in vitro in only two human livers and found to be greater than the activity in non-induced rat livers. In both the in vivo alkylation studies, the CBI values for TGIC in rat liver were relatively low, suggesting that only a small proportion of the administered dose binds to DNA. No studies for carcinogenicity or reproductive effects of TGIC were available for assessment. Assessment Of Occupational Exposure And Health And Safety Effects Health effects The extent of human health effects caused by a chemical is dependent on many factors, including toxicity of the chemical, particle size, bioavailability, metabolism, and duration and level of exposure level. Reports indicate that TGIC can cause allergic dermatitis in humans. Animal toxicity studies show that TGIC is toxic by oral and inhalational routes, is a skin sensitiser, is capable of causing serious eye damage and is genotoxic. A major factor in determining the potential for particles to be inhaled is particle size (aerodynamic diameter). Technical grade TGIC is commercially available as granules and the particle size data indicate that the granules are larger than 400 micro.m and therefore unlikely to be inhaled. Only very small amounts (eg < 0.003%) of technical grade TGIC are in the respirable range. TGIC powder coatings also have very low levels of particles (eg < 2.5%) in the respirable range. However, the majority of powder coating particles are smaller than 100 micro.m and therefore have the potential to be inhaled. The extent of bioavailability of TGIC in powder coatings is essential in determining the risk to humans of using powder coatings. In powder coatings, TGIC is partially cross-linked to the polyester resin and is expected to be biologically unavailable when so bound. Ciba-Geigy have stated that they have preliminary results which indicate that the amount of unbound TGIC in formulated powder coatings is 10 to 15% of the nominal TGIC content. Nissan provided limited data indicating that the amount of unbound TGIC in two 5% TGIC pigmented powders was 39.5% and 54.5%. The data indicate that the amount of unbound TGIC varies between different powder coatings. It is therefore advisable to assume that all TGIC in powder coatings is bioavailable when considering powder coatings as a group. There are a number of biochemical processes that transform chemicals into metabolites. Metabolism, such as by hydrolysis, usually results in detoxification of the chemical. Some mitigation of the mutagenic effects of TGIC seen in vitro may be expected through enzymatic hydrolysis. This hydrolysis is likely to be catalysed by microsomal epoxide hydrolase and involve the hydrolysis of the epoxy groups. The available data does not demonstrate that epoxide hydrolase is protective against the adverse effects to TGIC in humans. Exposure Standard The setting of a national exposure standard for atmospheric levels of TGIC in the workplace is not within the scope of this assessment. National Exposure Standards are declared by the National Occupational Health and Safety Commission. However, to provide guidance for manufacturers and end users of powder coatings, this assessment has recommended an interim occupational exposure limit for TGIC. There are no human health data or chronic animal toxicity data available on which to establish an occupational exposure limit. The toxicological animal data for TGIC are limited to acute studies. The most sensitive measured endpoint for TGIC effects in animals is genotoxicity. Therefore, in the absence of other relevant information, the most appropriate study for setting an interim exposure limit is a recent 5 day, repeated dose inhalational study examining TGIC induction of chromosomal aberrations in mouse spermatagonia, performed by Safepharm Laboratories (Project No. 14/75, May 1992). In the Safepharm study, exposure to atmospheric TGIC at the dose level of 7.8 mg/m3 did not induce chromosomal aberrations or cytotoxicity of the spermatogonia cells and adverse clinical signs were not observed. Therefore, the dose level of 8 mg/m3, together with a safety factor of 100, have been used to determine the limit. It is recommended that an interim occupational exposure limit for atmospheric levels of TGIC in the occupational environment of 0.08 mg/m3 (time-weighted average concentration over an eight-hour working day) be used by industry. This interim exposure limit is provided as guidance and is provisional until chronic data are available or until declaration of a national exposure standard. It is inappropriate to recommend an occupational exposure limit for all powder coatings because of the variability in the ingredients and amount of bound TGIC in the powders. When monitoring total dust levels in powder coating workplaces it must be assumed that all TGIC is bioavailable. For example, when using 5% TGIC powder coatings a total dust level of 1.6 mg/m3 should not be exceeded to ensure that the recommended occupational exposure limit for TGIC is not exceeded. Short term studies, such as the chromosomal aberration studies, should be regarded as severely limited with regard to setting occupational exposure standards. In the case of TGIC, this problem is also exacerbated by the shortcomings of the available studies themselves. Chronic toxicity data are necessary in order to confidently set an exposure standard to protect human health. It is recommended that ASCC give consideration to an exposure standard for atmospheric levels of TGIC in the occupational environment. Occupational Exposure The most likely routes of worker exposure to TGIC and TGIC powder coatings are inhalational and dermal. The greater the dust formation the greater the potential for worker exposure. During the manufacture of TGIC powder coatings the activities likely to cause high levels of worker exposure are weighing, filling hoppers, mixing, transfer of powder mixes in open vessels, extrusion, milling, bagging, cleaning up spills and cleaning and maintenance of equipment. During the use of TGIC powder coatings the most likely activities to cause high levels of worker exposure are filling hoppers, spraying, cleaning up spills, cleaning and maintenance of equipment and cleaning spray booths. Dust formation during these activities should be avoided or minimised by engineering controls and safe work practices. Personal protective equipment should be worn by workers if there is the potential for greater exposure, such as during manual spraying. Assessment of Control Measures To control worker exposure to TGIC, both manufacturers and users of powder coating have implemented a number of control measures. There are three manufacturers of TGIC powder coatings in Australia and they have all implemented similar measures to control worker exposure to TGIC. The control measures include isolation and automation of the process, engineering controls such as enclosure of the mixers and local exhaust ventilation in areas where TGIC dust may be generated, such as weigh booths, mixing, extrusion and milling areas and laboratory spray booths. Safe work practices have also been implemented. Personal protective equipment, which includes overalls, gloves and a filtered air hood with safety glasses or powered air respirator with integral visors, is worn by workers who are likely to be exposed to TGIC. The results of air monitoring data, conducted in two powder coating manufacturing plants in 1991, were supplied by ICI Dulux, Australia and Nissan, Japan. The data were considered in the context of the recommended occupational exposure limit of 0.08 mg/m3 for TGIC. The data from Nissan indicated that the levels of TGIC were well below the recommended limit. The initial data from ICI Dulux showed the majority of measurements for atmospheric TGIC were above 0.08 mg/m3. However, after changes had been implemented at the plant, principally improved work practices, atmospheric levels were measured and found to be below 0.08 mg/m3. The air monitoring data from Nissan and ICI Dulux demonstrate that levels of atmospheric TGIC in powder coating manufacturing plants can be controlled below the recommended limit of 0.08 mg/m3 for TGIC. There are over 500 spray painting workplaces applying powder coatings onto metal objects in Australia. The degree to which powder coating applicators implement and adhere to control measures varies considerably between workplaces. For example, workplaces differ on the degree of automation of the spray process, the type of booth, type and efficiency of ventilation, and on the respirator and protective clothing type and frequency of wear. The variation of control measures implemented in
spray painting workplaces is exemplified in the limited air monitoring
data available. The monitoring was conducted in 1991 by the Department
of Occupational Health, Safety and Welfare of Western Australia (DOHSWA).
There were marked differences in the levels of atmospheric TGIC and
total dust between and within workplaces. TGIC levels in dust samples
taken from three of the seven workplaces measured were above 0.08 mg/m3.
In particular, in one workplace the atmospheric levels of TGIC were
20-fold greater than 0.08 mg/m3. Public Health Assessment The TGIC in powder coated metal articles available to the public is fully cross-linked with the polyester resins, ie completely reacted into an inert form, and therefore poses no health risk. It is possible that public exposure could result from an accident during transport of either TGIC or TGIC powder coatings. In the case of TGIC spills, the risk of exposure from TGIC is minimal as it is imported in a pelletised or granular form which reduces dust production. Environmental Assessment There are three companies which manufacture TGIC powder coatings. Environmental exposure to TGIC resulting from manufacture of powder coatings is expected to be minimal as dust extractors, settling tanks and other pollution control devices will remove particulate waste for disposal. TGIC contained in such waste will be effectively immobile after consignment to landfill particularly if waste powder is heat cured beforehand. Environmental exposure to TGIC resulting from normal use in spray painting workplaces is also expected to be low as electrostatic application is an efficient application method. Powder which does not reach the target article (estimated at 2%) will be removed using dust extractors or cured in the original containers before sending to landfill. A high proportion of the TGIC in powder coatings will become immobilised through cross-linking in an insoluble polyester matrix. As TGIC is an epoxide, any residues which escape such capture and enter the open environment are expected to be rapidly degraded, either through microbial action or abiotic hydrolysis. TGIC residues will have limited persistence because of the lability of the epoxide substituents and are not expected to bioaccumulate. Only limited ecotoxicological data for TGIC are available. The 96 h LC50 obtained in static studies on zebrafish ( Brachydanio rerio) exceeded 77 mg/L (average of measured concentrations at 0 and 96 h), as did the NOEC. The 24 h EC50 in a static Daphnia magna immobilisation test was above 100mg/L, with a NOEC of 58 mg/L. These results indicate that TGIC is, at most, slightly toxic to aquatic fauna under conditions of acute exposure. Chronic effects would not be expected because of limited aquatic persistence. As an example of release from a formulation plant, ICI Dulux estimates daily releases of TGIC to sewer of 15 kg. Passage through Werribee Treatment Complex (500 ML daily flow) would dilute this release to a concentration of 30 ppb, assuming that mixing is uniform and no removal takes place. This clearly provides an adequate safety margin for aquatic fauna, even when other waste streams containing TGIC are added, since the NOEC for daphnids was some 2000 times this level. The predicted environmental hazard is low. TGIC and TGIC powder coatings are unlikely to present a risk to the environment. Conclusion From the assessment of the hazards of TGIC it is concluded that the chemical is a hazardous substance. TGIC is toxic by oral and inhalational routes, capable of causing serious eye damage, a skin sensitiser and is genotoxic. There is no chronic toxicological data available. The available repeat dose of toxicological data are limited and some of the results are questionable and that there are a number of critical data gaps, further studies are recommended in order to confidently predict the potential human health effects of TGIC. To provide guidance for manufacturers and applicators of TGIC powder coatings, this report has recommended an interim occupational exposure limit of 0.08 mg/m3 for TGIC. This limit is provided as guidance until chronic data is available or a national exposure standard is established. Adequate control measures must be implemented in powder coating manufacturing plants and in spray painting workplaces to ensure worker exposure is maintained at the lowest practicable level. In any case, the level of exposure should not be greater than the recommended interim occupational exposure limit of 0.08 mg/m3 for TGIC. Air monitoring data for powder coating manufacturing plants in Australia and Japan have shown that levels of atmospheric TGIC can be maintained below the recommended occupational exposure limit. Manufacturing plants as a rule have stringent control measures which include automation and enclosure of the process, ventilation, safe work practices and the wearing of respiratory protective equipment. The data suggest that where the recommended limit was exceeded at the ICI Dulux plant adequate control was later achieved, primarily by improvements in work practices. In the case of spray painting workplaces, adequate control can also be achieved but there is greater scope for worker exposure. Air monitoring data and workplace assessments have shown that there is a much greater variability in the control of worker exposure during application of powder coatings. Workplaces were able to control atmospheric levels of TGIC below the recommended limit using control measures such as enclosure, automation, ventilation and safe work practices. However, it was evident that some workplaces did not have the necessary controls to adequately protect workers unless workers wore full protective equipment. From the assessment of the known hazards of TGIC, overseas experience and air monitoring data we have concluded that TGIC is unlikely to cause adverse human health effects if the appropriate control measures and atmospheric monitoring strategy are implemented. However, the lack of chronic data makes it difficult to predict the long term health effects in workers exposed to TGIC. TGIC is unlikely to present a risk to the public or the environment and there are no specific recommendations for controls in these areas. Recommendations Classification and Labelling TGIC is classified as toxic by the oral and inhalational routes, capable of causing serious eye damage, a skin sensitiser, and a category 2 mutagen, in accordance with the health effects criteria detailed in the National Commission's Guidance Note for Determining and Classifying a Hazardous Substance. Based on the classification of its health effects and in accordance with the guidance note, TGIC is considered to be a hazardous substance. The complete requirements for the labelling of hazardous substances are detailed in the Guidance Note for the Labelling of Workplace Substances. The following risk phrases and appropriate safety phrases have been determined by application of the criteria given in the labelling guidance note and will ensure that the labelling requirements of the National Commission's National Model Regulations to Control Workplace Hazardous Substances have been met. Risk phrases: R23/25-41-43-46 Where
Appropriate safety phrases include:
Where TGIC is an ingredient in a mixture/preparation, as in powder coatings, the following concentration limits apply:
The above represent classifications for preparations containing TGIC at concentrations between the ranges shown. However, should there be other hazardous ingredients present in the preparation the overall classification for the preparation needs to be determined. In this case users should refer to the National Commission's Guidance Note for Determining and Classifying a Hazardous Substance for further guidance. As TGIC is a hazardous substance, employers and suppliers should be aware of their obligations to provide information, such as a MSDS, about the hazards of TGIC. Employers have a further obligation to assess and control the risks to health. Details of these obligations, consistent with employers general duty of care, are provided in the National Model Regulations to Control Workplace Hazardous Substances. As all States and Territories have made a commitment to enact uniform regulations consistent with this national Model Regulation in 1993, employers should read the recommendations of this report in conjunction with the obligations set out in these regulations. Exposure Standard It is recommended that the National Occupational Health and Safety Commission give consideration to setting a national exposure standard for atmospheric levels of TGIC in the occupational environment. In the interim, it is recommended that an occupational exposure limit for TGIC of 0.08 mg/m3 (time-weighted average concentrations over an eight-hour working day) should be used by industry. This limit is provided as guidance only and the lack of proper scientific data for the setting of this limit is recognised. Further toxicity testing As a result of this assessment, it was recognised that there were a number of critical data gaps in the chronic animal toxicity data for TGIC. TGIC was positive in a number of short term in vivo and in vitro genotoxicity studies and has been shown to covalently bind to DNA. Scientific data indicates that short-term tests for genotoxicity are helpful in predicting carcinogenic potential of chemicals. This raises the question of potential carcinogenic effects of TGIC. Estimation of carcinogenic potential can only be made from a cancer bioassay. It is recommended that a cancer bioassay with TGIC be conducted. In addition, the lack of chronic toxicity data creates difficulties both in predicting potential human health effects and in satisfactorily establishing an occupational exposure standard. It is recommended that the toxic effects following prolonged and repeated exposure to TGIC be investigated. It would therefore be prudent that a combined chronic inhalational toxicity/carcinogenicity study be conducted to determine both the chronic toxicity effects and carcinogenic potential of TGIC in a mammalian species. The reproductive effects of TGIC were brought into question when the results of a dominant lethal study and chromosomal aberration studies indicated cytotoxicity of spermatogonia at low dose levels. TGIC did induce chromosomal aberrations and cytotoxicity following oral and inhalational administration. This data suggests that TGIC may be a reproductive toxicant. In order to determine the reproductive and developmental effects of TGIC, relevant animal studies, such as a multigeneration reproduction study, are advisable. Atmospheric monitoring Atmospheric monitoring in both powder coating manufacturing plants and spray painting establishments should be carried out routinely. The frequency of monitoring should ensure that the interim occupational exposure limit of 0.08 mg/m3 for TGIC is not being exceeded and that the health of workers is therefore being protected. Atmospheric monitoring provides a quantitative estimate of worker exposure, identifies areas where high levels occur and provides a basis for measuring the effectiveness of control improvements. As manufacturers of powder coatings handle 'pure' (technical grade) TGIC, routine air monitoring of TGIC should be carried out. Air monitoring in these plants should be carried out where exposure is likely to occur, such as where filling of hoppers, milling, extrusion and bagging take place. Routine air monitoring of spray painting workshops should be carried out to ensure that the interim limit of 0.08 mg/m3 for TGIC is not being exceeded. The most accurate method is to measure atmospheric levels of TGIC but it is recognised that this method may not be practical. Routine monitoring for total dust may be more practical. However, as discussed previously the bioavailability of TGIC in powder coatings has not been established and therefore it must be assumed that all TGIC in powder coatings is bioavailable. For example, in a workplace using 5% TGIC powder coatings the total dust level should not exceed 1.6 mg/m3. Monitoring should be carried out where worker exposure to TGIC in spray painting workshops is likely to occur, such as during filling hoppers, spraying and clean up operations. Methods used for air monitoring and determination of TGIC content have been received from Nissan Chemical Industries Ltd, Japan and Ciba-Geigy Pty Ltd, Switzerland. The validity and suitability of these monitoring techniques have not been assessed in this report. For advice and assistance in monitoring contact State or Territory Occupational Health and Safety authorities. Control of Occupational Exposure Consistent with good occupational hygiene principle, that all worker exposure should be minimised, spray painters and manufacturers of powder coatings should aim for the lowest practicable levels of atmospheric TGIC and TGIC powder coating. In any case, the levels should not exceed the interim exposure limit of 0.08 mg/m3 for TGIC. Experience has shown that this level can be achieved and maintained in powder coating manufacturing plants where there are hazard control measures, safe work practices and, where necessary, personal protective equipment is worn. Data indicate that although the recommended exposure
limit can be achieved in spray paint workshops, it was often exceeded
where control measures, work practices and personal protective equipment
vary and are often inadequate. Isolation The spray painting process should be separate from
other workplace activities, such as by distance or in another building. Spray painting booths and equipment should be in
accordance with Australian Standard 3754 - 1990 Safe Application of
Powder Coatings by Electrostatic Spraying. In particular, the design of
the booth should be such that airborne powder does not escape from the
booth into the workplace. For all installations, local exhaust
ventilation should be provided and the average air velocity through each
booth opening should be not less than 0.4 m/sec. Other considerations in the use of hoppers are:
Electrostatic spray painting brings electrical hazards and additional safe work practices are required. For example, all equipment, including spray guns and booth, should be earthed. All hooks used to suspend objects to be sprayed should be cleaned prior to re-use in order to maintain effective metal contact. Earthing of equipment, objects being coated and personnel ensures maximum coating efficiency and reduces free dust as well as preventing build-up of static charges capable of causing ignition. Personal protective equipment Control of worker exposure should be achieved as far
as is practicable by means other than the use of personal protective
equipment. However, when other control measures, such as engineering
controls and safe work practices, do not adequately protect the worker
then personal protective equipment should be worn.
Workers who may come into direct contact with TGIC powder coatings include persons:
Manufacture Of Powder Coating Where applicable, the controls measures outlined above for spray painting should be implemented in the powder coating manufacturing plant. These measures include isolation of the formulation process, enclosure, automation, local exhaust ventilation and the wearing of personal protective equipment when necessary. Any open process or leakage will increase worker exposure. Any manual process will also increase worker exposure. Local exhaust ventilation should be provided when
filling the hoppers, when adding to the mixer, during mixing, extrusion
and bagging, and at open transfer points.
Requirements For Secondary Notification Under the Industrial Chemicals (Notification and Assessment) Act 1989 (the Act), secondary notification of triglycidylisocyanurate shall be required if any of the circumstances stipulated under Subsection 64(2) of the Act arise.
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