|
Home : Publications : Car : Pec : Pec4 |
|
|
|
NICNAS Matters and NICNAS e-Newsletter ................................. Quick links ................................. |
Priority Existing Chemical Assessment Reports - Glutaraldehyde
Introduction The chemical 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), Chemical Abstracts Service Number 306-83-2, was declared a PEC by the Minister for Industrial Relations by notice in the Chemical Gazette of 1 June 1993. Importers of HCFC-123 were obliged under section 55 of the Industrial Chemicals (Notification and Assessment) Act 1989 (Cwlth) to apply for its assessment. HCFC-123 is not manufactured in Australia. Information for assessment was obtained from applicants, end-users, manufacturers, international organisations and scientific literature. Additional exposure data were obtained from an air monitoring survey conducted by Worksafe Australia. Background Global concern over the depletion of the stratospheric ozone layer by chlorofluorocarbons (CFCs) and halons resulted in the Montreal Protocol on Substances that Deplete the Ozone Layer (1987). Under the Ozone Protection Act 1989 (Cwlth), in line with the Montreal Protocol, the production and importation of halons and CFCs are to be totally phased out by 1996. The phase-out of CFCs and halons has created a need for acceptable substitute chemicals. Currently the most suitable replacements for many of the applications of these substances are hydrochlorofluorocarbons (HCFCs). In Australia, HCFC-123 is currently being used as an interim replacement for CFC refrigerants (mainly CFC-11) and as a component of HCFC fire extinguishant blends which are being introduced as interim replacements for halons, mainly Halon 1211 and Halon 1301. Applicants
Association of Fluorocarbon Consumers and Manufacturers
Elf Atochem Pty Ltd
Lovelock Luke Pty Ltd
North American Fire Guardian Technology (Australia) Pty Ltd Chemical identity HCFC-123 is listed on the Australian Inventory of Chemical Substances as ethane, 2,2-dichloro-1,1,1-trifluoro- and has a molecular weight of 152.9. HCFC-123 is a clear, colourless liquid with a slight ethereal odour. HCFC-123 is hydrolytically stable, but is incompatible with alkali or alkaline earth metals. Although non-flammable at high temperatures, HCFC-123 may decompose to form free halogen, HF, HCl, dichloroethylene, phosgene and small amounts of other halogenated alkanes. The physicochemical data listed below relate to commercial grade HCFC-123.
ODP Ozone Depleting Potential. Commercial samples of HCFC-123 refrigerant contain > 99% HCFC-123. Internationally, commercial samples of extinguishant blends containing HCFC-123 include HCFC-123 concentrations of 4-93%. Methods of detection and analysis HCFC-123 has been characterised by infra-red (IR), nuclear magnetic resonance (NMR), Raman and mass spectrometry. Routine atmospheric monitoring has been undertaken using personal or static monitoring and analysis using capillary gas chromatography (GC) and flame ionisation detection (FID). The detection limit is reported to be less than one part per million (ppm). Other methods that have been used to monitor peak airborne levels of HCFC-123 include portable GC and IR and indicator tubes. Fixed (peak) monitoring systems are available for HCFC-123 (vapour) detection in the workplace. The most sensitive systems employ IR sensors, but the most commonly used systems use halide ion and metallic oxide (resistance) detectors. The detection limit for most monitors is around 1 ppm, with a limit of quantification of around 5 ppm. Some systems employ an integrator facility to provide a computation of the time-weighted average (TWA) exposure levels. Fixed systems that monitor levels of uncondensed gas bubbles (an indicator of refrigerant leakage) in the refrigerant liquid line are also available. Importation and use In Australia, the main use of HCFC-123 is as a refrigerant, as a replacement for CFC-11 in low pressure centrifugal chillers for air conditioning systems. HCFC-123 has also been used to a limited extent to replace CFC-12 in retrofitted high pressure chillers. Current imports of HCFC-123 refrigerant are around 25 tonnes per year, with an estimated future usage of up to 85 tonnes per year. Smaller amounts of HCFC-123 are being used in fire extinguishant blends (total flooding and streaming agents) which are being used as replacements for Halon 1211 and Halon 1301. Streaming agents are used in portable (hand-held) fire extinguishers, whereas total flooding agents are used in fixed systems. Imports of total flooding agents containing HCFC-123 are currently around 10 tonnes per year (equivalent to 500 kg of HCFC-123), with future usage estimated at 50-100 tonnes per year. These figures do not account for HCFC-123 in streaming agents, and hence may be a significant underestimate. Neither HCFC-123 nor extinguishant blends containing HCFC-123 are manufactured in Australia. Exposure assessment Environmental exposure HCFC-123 does not occur naturally in the environment nor is it manufactured in Australia. The main source of environmental exposure to HCFC-123 is from operation and maintenance of low pressure chillers, which are estimated to lose less than 1% of their charge per year. No data were available on quantities likely to be released to the environment from use in fire fighting, but the current contribution to total HCFC-123 emissions is considered to be small as imports are currently at a low level and fires occur infrequently. Discharge of extinguishant may occur during installation and testing, although restrictions on this practice are likely to be implemented. Minor releases may also result from transport, storage, recycling and disposal operations. Occupational exposure to HCFC-123 refrigerant Maintenance of centrifugal chillers Chiller maintenance technicians may be exposed to HCFC-123 during maintenance procedures and the main sources of exposure are:
Exposures of maintenance workers during refrigerant transfer occur during connection and disconnection of transfer lines and hoses from the recovery unit and chiller, where both vapour escape and spillage of liquid refrigerant may occur. Additionally, HCFC-123 vapour may be vented into workroom air during vacuum pump operation. Exposures to maintenance personnel during leak testing may occur during pressurisation of the condenser (should leaks be present) and from release of the inert gas (nitrogen) holding charge (if vented into workroom air), which may contain a significant amount of residual HCFC-123 vapour. Many chiller repairs require some degree of chiller opening or dismantling, often referred to as stripdown. Such work may lead to significant leakages of HCFC-123 vapour into the workplace depending on the degree of stripdown and the amount of residual refrigerant in the chiller. Extent of exposure of maintenance workers The extent of exposure of maintenance technicians to HCFC-123 is dependent on the number of hours spent at chiller installations and the type of work carried out. It has been estimated that in Australia at least 1000 chillers will be operating on HCFC-123 by the year 2010. Approximately 100 maintenance technicians would be required to maintain this number of machines. Technicians spend 20-1200 hours per year on chiller maintenance, which is equivalent to 1-30 hours per week on maintenance and repair operations. In addition, a technician may also spend 10-40 hours per week at chiller installations undergoing routine machine logging tasks which do not usually involve exposure to refrigerant. The maximum daily shift for a technician is 10 hours, and in most cases would be unlikely to exceed six hours. Air monitoring studies (refrigerant) A number of monitoring studies on HCFC-123 refrigerant have been carried out to characterise personal exposures (of maintenance technicians) during various maintenance and repair operations. Results indicated that although peak levels for some of the operations were highly variable, ranging from a few parts per million to several hundred parts per million, the TWA personal exposure levels were generally below 1 ppm and not greater than 5 ppm. Occupational exposure to HCFC-123 extinguishant blends The main exposure to extinguishants will be during fire suppression. High exposure levels are achieved following discharge of total flooding systems. However, exposure of workers to this source will be low due to the fact that discharges are intended for unoccupied areas. Both professional firefighters and other workers using portable extinguishers constitute workers with the highest potential exposures, although actual exposures to the former population group will be low due to the deployment of personal protective equipment, including self-contained breathing apparatus (SCBA) respirators. Exposures to other workers using portable extinguishers may be significant, particularly where the fire hazard is in a confined space. In addition, as indoor levels of HCFC-123 have been shown to be present several hours after discharge, exposure to workers entering or re-entering a hazard area might also be significant. Air monitoring studies (extinguishant) Indoor and outdoor monitoring studies on portable fire extinguishers were available for assessment. Levels of HCFC-123 measured in these studies indicated that, although highly variable, peak exposures did not exceed 1000 ppm. TWA levels from hand-held extinguishers (20 pound) were less than 15 ppm, one hour after exposure. Higher peak and TWA levels might be expected for confined areas. Public exposure Under normal conditions, the public is unlikely to be exposed to HCFC-123. Given that air conditioning equipment is usually housed in plant rooms or other inaccessible locations, it is not anticipated that public exposure to HCFC-123 will arise from maintenance activities. There is a small possibility that a major failure of a large chiller system could lead to significant exposure of the building occupants. In addition, there is a potential for low level exposure to HCFC-123 to building occupants from refrigerant contamination of the water cooling system, although such a scenario is unlikely. In the event of a fire, there is a potential for acute exposure of building occupants to HCFC-123 in HCFC-blend discharges. Levels of up to 1000 ppm and 5000 ppm of HCFC-123 have been measured/calculated for portable and total flooding extinguisher systems respectively. Higher levels could be attained for portable extinguisher systems in an enclosed, unventilated environment. Levels of HCFC-123 have been measured several hours after discharge of portable extinguishers, and a potential for low level exposure exists for occupants revisiting the hazard area. Toxicokinetics and metabolismHuman studies In vitro studies with human liver microsomes indicate that HCFC-123 is metabolised by cytochrome P450 enzymes, primarily by CYP 2E1. As with animal studies, the major metabolite is trifluoroacetic acid (TFA). Rates of TFA formation in human microsomes were an order of magnitude greater than in rat microsomes. Animal studies Absorption and distribution Partition coefficients for HCFC-123 in various organs indicate lipophilic characteristics and, as such, absorption and tissue distribution are expected to occur readily. Pharmocokinetic modelling of metabolic constants indicate a single saturation uptake pathway. In rats and guinea pigs 50-90% of the applied dose was taken up following six hours of HCFC-123 exposure. Up to 2% of dose was recovered in organs of rats and 6% in guinea pigs. Similar distribution profiles were seen in both species, with the liver containing most of the radiolabel, followed by testes, kidney, lung and brain. Biotransformation and protein binding Approximately 25% of the dose of HCFC-123 undergoes biotransformation in rats and guinea pigs. As with human studies (in vitro), HCFC-123 is metabolised by liver CYP 2E1 and the major urinary metabolite is TFA. Other minor metabolites of HCFC-123 detected in rat and guinea pig urine were N-trifluoroacetyl-2-aminoethanol and N-acetyl-S-(2,2-dichloro-1,1-difluoroethyl)-L-cysteine. The metabolites, 2-chloro-1,1,1-trifluoroethane and 2-chloro-1,1-difluoroethene, formed by reductive metabolism of HCFC-123, have also been detected in vitro and in vivo in rat liver. Biotransformation of HCFC-123 to TFA appears to be both saturated and inhibited above 1000 ppm. Binding of HCFC-123 metabolites to tissue proteins (including blood proteins) has been demonstrated in rats and guinea pigs. Trifluoroacetylchloride appears to be the metabolite associated with this binding, as N-trifluoroacetylated lysine residues have been identified in liver proteins. In both rats and guinea pigs, the highest levels of protein adducts are found in the liver, with lower levels in kidney, lung and brain. Protein adducts in testes and pancreas were not detected. Studies on the rate of protein binding and TFA excretion in rats indicate that metabolism of HCFC-123 is the rate limiting step with respect to the observed saturation of these metabolic processes. Elimination and excretion HCFC-123 has been detected in expired breath from rats and appears to be the main route of elimination. Approximately 25% of the estimated uptake was recovered in the urine of rats and guinea pigs during 48 hours post-exposure. Urinary TFA elimination rate in rats was linear up to 48 hours post-exposure with saturation occurring above 1000 ppm. Effects on experimental animals and in vitro bioassaysAcute toxicity HCFC-123 has a low oral toxicity (approximate lethal dose [ALD] was around 9000 mg/kg body weight in rats) and dermal toxicity (LD50 > 2000 mg/kg in rats and rabbits). LC50 values (4 hours) were 32,000-53,000 ppm in rats. Reversible central nervous system (CNS)/behavioural effects were seen in rats, EC50 (1 hour) 4000 ppm. Hepatic effects were seen at the lowest dose tested (1000 ppm) in guinea pigs and cardiac sensitisation in dogs, EC50 (5 min) 19,000 ppm, and a no effect level of approximately 10,000 ppm. Irritation and sensitisation HCFC-123 was not irritating to the skin of rabbits or guinea pigs, but was slightly irritating to the rabbit eye. No evidence of dermal sensitisation potential was found in guinea pigs. Repeat dose toxicity (inhalation) Several sub-acute repeat dose inhalation studies have been performed in rats, and guinea pigs. The main effects were CNS depression, liver and testicular injury. Reversible CNS effects were seen in rats at 5000 ppm. HCFC-123 caused liver damage in both species with a LOAEL of 1000 ppm determined in rats. Testicular damage was seen in rats above 18,000 ppm, but not in guinea pigs. Sub-chronic (90-day) toxicity studies have been performed in rats and dogs. The main effects were CNS depression and liver injury. Reversible CNS effects were seen in both species above 5000 ppm. However, no histological effects on the brain or nerve tissues were seen in rats. In both species, HCFC-123 caused liver damage (NOAEL 300 ppm in rats, NOAEL 1000 ppm in dogs). In one rat study this was demonstrated as reversible (30 days post-treatment). A chronic (two-year) study was conducted in rats at 300, 1000 or 5000 ppm. Treatment-related effects were seen in the liver, pancreas and reproductive system at all exposure levels. At termination, hepatic effects included hepatomegaly, cholangiofibrosis (in females), necrosis, centrilobular fatty change and biliary hyperplasia. Also seen at the highest exposure levels were significant increases in the incidence of hepatocellular adenoma (both sexes) and cholangiofibroma (females only). In the pancreas, an increased incidence of acinar cell focal hyperplasia (in both sexes) and adenoma (in males) was seen at 1000 ppm and 5000 ppm. Male rats exhibited dose-related increases in seminiferous tubule atrophy and interstitial (Leydig) cell hyperplasia. Although an increase was also seen in interstitial cell adenomas (especially bilateral), a dose-response relationship was not evident. The study did not demonstrate a NOAEL. Levels of b -oxidation activity (measured in sub-acute, sub-chronic and chronic studies) indicate that HCFC-123 is a mild peroxisome proliferating substance in rats. Hypolipidaemic effects were also evidenced by decreases in serum triglycerides and cholesterol in rats and guinea pigs. Reproductive toxicity Developmental toxicity studies have been performed in rats and rabbits. In neither species was there evidence of any adverse effect on foetal viability, growth or development. Increased resorption rate and low foetal weight and foetal tail defects seen in rabbits at 10,000-20,000 ppm HCFC-123 were ascribed to maternotoxicity. A two-generation inhalation reproduction toxicity study in rats (exposed to 30, 100, 300 or 1000 ppm of HCFC-123) revealed no effects on fertility (pre-mating interval, copulation index, pregnancy rate or histological effects in reproductive organs) or lactation (serum cholecystokinin [CCK] concentration or milk fat content). With respect to development, no significant effects were seen on number of implantation sites, embryonic losses, sex ratio, litter size or the number of live-born pups. However, effects on both sexual maturation and mean pup weights were seen at and above 30 ppm and 300 ppm respectively. In adults, histological changes seen in the liver (LOAEL 300 ppm, NOAEL 100 ppm) included enlarged centrilobular hepatocytes and vacuolated centrilobular and/or periportal hepatocytes. Overall, the study did not demonstrate a NOAEL. Genotoxicity HCFC-123 did not cause reverse mutation in Salmonella typhimurium or forward mutation in Saccharomyces cerevisiae, either in the presence or absence of metabolic activation. Conflicting results were seen between in vitro and in vivo clastogenicity studies in lymphocytes. Other bioassays (including cell transformation, mouse micronucleus test, and UDS assay) were all negative. Human health effectsLittle data on human health effects were available for HCFC-123. However, health effects from exposure to other HCFCs and structural analogues have been documented. Effects from acute exposures include CNS, liver and cardiopulmonary effects together with asphyxiation at very high levels. Chronic effects are less well characterised and include neurological disturbances and hepatic toxicity. Hydrochlorofluorocarbons Acute exposure to HCFC-123 caused effects such as dizziness, headaches and nausea in around 40 workers exposed to HCFC-123 following the rupture of an industrial chiller. Leakage of HCFC-22 refrigerant at an ice rink resulted in one death and 34 cases of acute intoxication that included nausea, CNS depression and coughs. Hospital personnel exposed to HCFC-22 in tissue preservative exhibited a higher incidence of coronary heart disease, although an epidemiological study showed no excess mortality from cardiovascular or malignant disease in workers exposed to HCFC-22. Neurological disorders and haematological effects have been reported in workers chronically exposed to HCFC-22 and HCFC-142b. Chlorofluorocarbons Fatalities have been reported from the use and abuse of aerosol products containing CFC propellants. Chiller maintenance workers exhibited a reduction in ventilatory lung capacity and a significant decrease in heart rate following 2 hours exposure to 10,000 ppm CFC-12. No electrocardiogram or pulmonary function effects were seen from repeated exposure (8 hours per day for 4 weeks) of volunteers of up to 1000 ppm CFC-11 or CFC-12. Limited evidence of skin sensitisation exists for both CFC-11 and CFC-12 from use in deodorant sprays. Fatalities have been reported from asphyxiation and cardiac arrhythmia in workers exposed to CFC-113 in solvent applications, including one death from exposure to a vapour concentration of around 130,000 ppm. No signs of adverse effects were reported in workers exposed for over two years to CFC-113 in the range 45-4700 ppm, although acute (up to 2 hours) exposure of volunteers to 4500 ppm caused significant impairment of manual dexterity and concentration. Halons (bromofluorocarbons) Effects reported from exposure to halon fire extinguishants include paraesthesia, tinnitus, anxiety, slurred speech and electroencephalographic changes together with eye and respiratory irritation. Convulsive seizures and respiratory arrest have been documented in firefighters exposed to chlorobromomethane. Volunteers exposed to Halon 1301 showed electrocardiographic irregularities at exposures of 70,000-150,000 ppm, with paraesthesia and other CNS effects above 100,000 ppm. A number of fatalities have been reported for Halon 1211, including a death from exposure to around 120,000 ppm Halon 1211 from discharge of 3 kilograms of extinguishant into a confined work area. Both cardiac and hepatic effects (halothane hepatitis) have been well documented in humans during halothane anaesthesia (levels of 10,000-40,000 ppm). Similarities in metabolites, protein binding and acute toxicity between halothane and HCFC-123 (in animal studies) indicate a potential for similar hepatotoxic profiles in humans. Hepatic toxicity has also been well documented in humans from exposure to other halogenated alkanes, including 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane and bromoethane and 1,1-dibromoethane. Pyrolysis products Potential products of combustion (POCs) for HCFC-123 include free halogen, HCl, HF and phosgene. Cases of phosgene poisoning have been reported following thermal decomposition of CFC-11. Toxic combustion products of HCFCs are of particular relevance to HCFC extinguishant blends where, in addition to POCs, toxic products may also be formed by reaction with burning materials during fire suppression. Human health hazards and classificationClassification of health effects (in this section) has been carried out according to the National Occupational Health and Safety Commission's (National Commission) Approved Criteria for Classifying Hazardous Substances (the Approved Criteria). Toxicokinetics and metabolism In rats and guinea pigs, HCFC-123 is metabolised similarly in terms of uptake, distribution profiles and extent and rate of elimination of urinary metabolites. Metabolic studies indicate that trifluoroacetic acid (TFA) is the major metabolite in both species and that biotransformation is saturated and inhibited above 1000 ppm in rats. Evidence indicates that reactive oxidative metabolites (possibly triflouroacetyl chloride) are associated with acute hepatotoxicity. Covalent binding of HCFC-123 metabolites was only seen in the liver, although distribution to other target organs (that is, testes and pancreas) occurs, no evidence of binding was detected in these tissues. Evidence from in vitro studies indicates that a similar metabolic profile for HCFC-123 might be expected in humans. Acute effects In animals, cardiac sensitisation, CNS depression and liver toxicity are the critical effects following acute exposure to HCFC-123. Evidence indicates that these effects are relevant to humans. The inhalational LC50 for HCFC-123 in rats is above 28,000 ppm and LD50 for oral and dermal toxicity are above 2000 mg/kg. The oral ALD in rats is approximately 9000 mg/kg HCFC-123. No observed effect levels for CNS effects and cardiac sensitisation in animals are 2500 ppm and 10,000 ppm respectively. Liver effects were seen in guinea pigs at the lowest dose tested (1000 ppm). Classification status HCFC-123 does not meet the Approved Criteria for acute lethal effects, but could not be classified for non-lethal irreversible effects after single exposure, due to inadequate data. Irritation and sensitisation There are no reports on the irritation or sensitisation potential of HCFC-123 in humans. Tests in rabbits and guinea pigs indicate that HCFC-123 is not a skin irritant, but it is a slight eye irritant in rabbits. HCFC-123 tested negative in a skin sensitisation study in guinea pigs. Classification status HCFC-123 does not meet the Approved Criteria for irritant effects (skin and eyes) and sensitising effects (eyes). Non-carcinogenic effects from repeated exposure There are no reports of adverse effects in humans following repeated or prolonged exposure to HCFC-123. Studies in animals include several sub-acute and sub-chronic studies together with a two-year chronic study in rats. The main effects seen in these studies were on the CNS, liver, testes and pancreas. The NOAEL for CNS effects was 1000 ppm in rats and dogs. No histological effects were seen in brain, spinal cord and nerve fibres of rats exposed (90 day) to 5000 ppm HCFC-123. Adverse hepatic effects were seen in rats, guinea-pigs and dogs following repeated exposure to HCFC-123. The NOAEL and LOAEL reported for hepatic effects in rats (28 weeks exposure) was 100 ppm and 300 ppm respectively. In other repeat-dose studies similar lesions were reported (at 300 ppm) as either reversible or not significant up to 12 months exposure. Adverse testicular effects were seen in sub-acute inhalation studies in rats, but not in guinea pigs. A LOAEL of 300 ppm for testicular effects and a NOAEL of 300 ppm for pancreatic effects was determined (in rats) from chronic exposure to HCFC-123. Classification status HCFC-123 does not meet the Approved Criteria for severe effects after prolonged exposure (by inhalation). Genotoxicity HCFC-123 showed no evidence of mutagenicity with in vitro bacteria or yeast tests and in vivo mouse micronucleus test. HCFC-123 also showed no evidence of inducing primary DNA damage by unscheduled DNA synthesis or cell transformation. Evidence for clastogenicity, from in vitro and in vivo lymphocyte studies, was conflicting. Classification status HCFC-123 does not meet the Approved Criteria for mutagenic effects. Carcinogenicity Chronic exposure to HCFC-123 elicited benign tumours (liver, pancreas and testes) in rats at and above 300 ppm. Available data indicate that HCFC-123 is non-genotoxic. Mechanistic data indicate that liver adenomas may be related to increases in hepatic peroxisome proliferation. Liver cholangiofibromas seen only in females at the highest dose level were considered biologically significant, although little is known of the relevance of this tumour type to humans. Mechanistic data indicate an association between HCFC-123 elicited pancreatic acinar cell tumours and hormone perturbations which might account for the sex specificity (males only) of this tumour in rats. Pancreatic acinar cell cancers are reportedly rare in humans. Evidence indicates that HCFC-123 elicited testicular Leydig cell adenomas are also associated with hormone changes and may also be related to hepatic peroxisome proliferation. In addition, Leydig cell adenomas are reportedly rare in humans but common in aging rats (strongly associated with senile endocrine disturbances). Although the relevance of HCFC-123 elicited Leydig cell and liver adenomas to humans is highly questionable, mechanisms of cholangiofibroma and pancreatic acinar cell tumour formation require further characterisation before their relevance to humans can be ascertained. Classification status HCFC-123 meets the Approved Criteria for carcinogenic effects (Category 3[b]). According to the Approved Criteria, this classification is provisional and further studies are necessary before a final decision can be made. Reproductive effects Effects on fertility In rats, HCFC-123 did not influence pre-mating interval, copulation index, pregnancy rate or pup sex ratio but was associated with decreased implantation sites at 1000 ppm, a level at which overt maternotoxicity was observed. Adverse effects on testes were seen at 300 ppm in a chronic rat study. However, no effects on reproductive tissues were seen in a two-generation reprotoxicity study. Perturbations in serum sex hormone levels have also been reported in male rats and guinea pigs. However, due to inconsistencies both within and between studies, the biological significance of such findings is unclear. Classification status HCFC-123 does not meet the European Union criteria for effects on male or female fertility. Effects on development In rabbits, developmental effects were seen only at doses which caused maternotoxicity, that is, greater than 10,000 ppm. In rats, HCFC-123 caused reduced growth and sexual maturation in pups at and above 30 ppm and 300 ppm respectively. HCFC-123 did not affect serum CCK concentrations or milk fat content up to 1000 ppm. Reduced pup growth was not considered to be a developmental effect as reduction in weight was not apparent until seven days after birth. Delayed sexual maturation was ascribed to delayed pup growth. Inadequate evidence was available to evaluate an effect due to HCFC-123 transfer during lactation. Classification status HCFC-123 does not meet the European Union criteria for developmental toxicity and should not be classified as a substance toxic to reproduction (Category 3). Inadequate data were available to classify HCFC-123 according to effects during lactation. Human health risk characterisation Critical effects and exposures Acute effects Critical effects for acute HCFC-123 exposure are CNS depression, cardiac sensitisation and liver toxicity. No effect levels determined in animal studies for CNS/behavioural (rats) and cardiac sensitisation (dogs) are 2500 ppm and 10,000 ppm respectively. The most sensitive acute effect in animal studies was hepatotoxicity, seen at the lowest level tested in guinea pigs at 1000 ppm HCFC-123. Available information on HCFC structural analogues (including halothane) indicate that humans are likely to be less sensitive than animals to acute effects from HCFC-123 exposure. Chronic effects The critical effect identified for chronic exposure to HCFC-123 in animals was liver toxicity. Liver effects were seen in rats, guinea pigs and dogs and have been reported in humans for other halogenated ethanes. The lowest dose of HCFC-123 causing liver damage in repeat dose studies was 300 ppm, with a NOAEL of 100 ppm. Available evidence indicates that liver adenomas (seen at 300 ppm) result from a non-genotoxic mechanism and that a threshold for effect is likely. No evidence of preneoplastic lesions, protein binding, peroxisome proliferation and hormone perturbations were seen at 100 ppm and hence it is considered that this level of exposure represents a NOAEL for chronic effects from inhalation, particularly as the incidence of other target organ tumours (pancreas and testes) were not statistically significant compared to controls at 300 ppm. Occupational health risks Acute risks Risks of acute health effects are considered to be low during normal transport, handling and use (including chiller maintenance) of HCFC-123 refrigerant. Risks of asphyxiation are even lower and would only exist following a catastrophic leakage of refrigerant or where refrigerant vapour was allowed to accumulate in a confined working space or low lying area. Similarly, acute health risks during normal transport, handling of extinguishant blends (including filling operations) and during installation and testing of fire suppression equipment are expected to be low. Limited human exposure to HCFC-123 would be expected during discharge of total flooding extinguishants, due to their automated mode of discharge and containment. However, exposure levels would be high (approximately 5000 ppm of HCFC-123 for HCFC Blend A) and may present an acute health risk to workers remaining in the hazard zone. Concomitant exposure to other HCFCs in the blend may lead to an increased risk from additive effects. Due to their manual application, the potential for exposure to HCFC-123 from discharge of portable extinguishers is much greater than for total flooding systems. Although risks to professional firefighters would be reduced due to the deployment of pressure demand SCBA, risks to other workers using portables would be considerably higher, particularly in confined working areas. Concomitant exposure to other HCFCs in the blend may lead to an increased risk from additive effects. Limited evidence exists to suggest that some workers exposed to HCFC-123 may be at greater risk from acute cardiac effects than others, such as those with pre-existing cardiovascular disease or those using catecholamine medications. In addition to acute health risks from HCFCs in HCFC-blend extinguishants, there are additional risks from POCs and products formed by reaction with burning materials. Chronic risks The population at risk from chronic exposure to HCFC-123 refrigerant are chiller maintenance technicians. Exposure of technicians to HCFC-123 refrigerant is dependent on the number of hours spent at chiller installations (running on HCFC-123) and the types of maintenance activities carried out. Results from personal monitoring studies indicate that the TWA exposure during a normal working shift is generally below 1 ppm and up to 5 ppm. Chronic risks from HCFC-123 exposure were evaluated using the 'margin of safety' approach, that is, dividing the chronic animal NOAEL by the actual (monitored) occupational (TWA) levels. The 'margin of safety' for chiller maintenance technicians is 20-100. Taking into account the adequacy of the exposure and toxicity database, this margin is considered sufficient and the risk of chronic effects in maintenance workers is therefore considered low. Occupational exposures to either streaming or total flooding agents would be expected to be infrequent, thus the risk of chronic health effects from HCFC-blend extinguishants is considered to be extremely low. Public health risks Under normal conditions, the public is unlikely to be exposed to HCFC-123 and public health risks are considered to be very low. Acute exposure could occur as a result of a transport accident, given the high vapour pressure of the chemical. Leakage and release during chiller maintenance is likely to be confined to air conditioning plant rooms or to areas with restricted public access. Exposure from environmental sources is also unlikely as HCFC-123 will not be intentionally released into the atmosphere, or otherwise disposed of in Australia. Similarly, under normal conditions, no public exposure to extinguishants containing HCFC-123 should occur, particularly as extinguishants containing HCFC-123 are not anticipated for domestic use. Significant exposures could arise from: activation of a fixed fire extinguishing system within a building from which the occupants had not been evacuated; use of a portable extinguisher in a confined space; and entering an inadequately ventilated hazard area following discharge. However, such events are expected to occur rarely, and would not usually result in prolonged exposure to high concentrations of HCFC-123. OHS risk management Workplace control measures Elimination and substitution The use of HCFC-123 in the air-conditioning and fire protection industries is an interim measure and will ultimately be phased out under the Ozone Protection Act 1989 (Cwlth) . Based on environmental grounds, its use as an interim replacement for CFCs and halons has been endorsed by the Commonwealth Environment Protection Agency. In general, substitution requires great care as other substances may not offer a greater degree of safety and, indeed, many refrigerants and extinguishants in current use present additional hazards. Isolation In chiller systems, HCFC-123 is isolated, as the refrigerant is contained in a sealed system. Isolation of the refrigerant is also maintained during chiller maintenance activities by the use of portable refrigerant recovery devices. Portable and fixed extinguishants are contained in pressurised cylinders. Total flooding systems are further isolated in that extinguishant cylinder(s) are located away from the work area. In addition, measures are usually taken to confine extinguishant discharge, thus preventing exposure to personnel in nearby work areas. Engineering controls, safe work practices and personal protective equipment Refrigerant controls Current control measures employed in the air conditioning industry would appear to be sufficient to maintain TWA levels below 5 ppm HCFC-123. However, peak levels up to several hundred ppm have been recorded during certain chiller maintenance activities. In general, peak levels can be reduced by paying particular attention to measures aimed at ensuring efficient refrigerant recovery and adherence to safe work practices during maintenance and repair procedures, particularly during leak test operations. Such control measures are embodied in the following codes and standards:
These documents currently comprise the fundamental reference material used by chiller maintenance engineers in Australia. In general, these documents adequately address engineering controls and equipment design together with installation and servicing protocols. However, from an occupational health and safety perspective, better information could be provided on safe work practices, specific hazards of HCFC-123, and other replacement refrigerants, emergency procedures and training requirements (see below). Australian Standard AS 1677 is currently being reviewed. It is reported that the next update will incorporate information from other national and international standards. Extinguishant controls Control measures introduced to reduce exposures during firefighting for professional firefighters rely mainly on personal protective equipment (particularly SCBA), the selection of which is dealt with by the relevant authorities in each State and Territory. No formal control measures are applicable to reducing exposures to other workers using portable extinguishers and reliance is on adequate hazard communication and training (see below). A number of Australian codes and standards address measures aimed at limiting exposure to HCFC-blend extinguishants from both portable and fixed extinguishers, notably:
In general, these documents adequately address engineering controls and equipment design together with installation and testing protocols. However, from an occupational health and safety perspective, better information is required on safe work practices, training requirements (see below) and specific hazards of HCFC-blend extinguishants. Emergency procedures and training requirements Emergency procedures for refrigerant leaks or emergency shutdown/evacuation of chiller installations were not available for assessment, apart from guidelines for emergency discharge of refrigerants provided in the ASHRAE Safety Code for Mechanical Refrigeration. Key elements of an emergency response plan should include emergency shutdown procedures, emergency contact numbers, first aid procedures and an evacuation plan for building occupants, which should form part of the basic training for chiller technicians. A considerable amount of guidance material has been prepared for the safe handling and use of HCFC-123 refrigerant. In general, the material provided for assessment provides adequate information with respect to acute hazards. However, potential chronic effects are generally understated or absent. In addition to training in safe handling, there are special training requirements for training of workers involved in the use of ozone-depleting substances as specified in the Australian and New Zealand Environment and Conservation Council (ANZECC) Revised Strategy for Ozone Protection. Emergency response plans are required for transportation of HCFC-blend extinguishants, according to the Australian Code for the Transport of Dangerous Goods (ADG Code), and for response to extinguishant discharges. With regard to transportation, the appropriate information can be found in Emergency Procedure Guide 2C2. The Hazchem Code specified in the ADG Code requires the use of 'water fog' for the dispersal and dilution of spillage together with the use of full protective clothing. With regard to discharge from fixed extinguisher systems, emergency procedures should include fire drills (including an evacuation plan), first aid and clean-up and emergency contact numbers. Suitable safeguards should also be provided to prevent entry into hazardous atmospheres and to provide the means for prompt rescue of any trapped personnel. No formal training procedures were available for assessment, apart from fixed extinguisher testing procedures. Information should be provided to firefighters on the potential hazards of HCFC-blend extinguishants. Similarly, adequate training should be provided to other workers with occasion to use HCFC-blend portable extinguishers, particularly with respect to their use in confined working areas. Hazard communication Material safety data sheets Five material safety data sheets (MSDS) for HCFC-123 and two MSDS for HCFC-blend extinguishants were submitted for assessment and evaluated according to the requirements as set out in the National Commission's National Code of Practice for the Preparation of Material Safety Data Sheets. Although the majority of the MSDS submitted for assessment were rated as 'adequate' according to these criteria, none were considered 'nearly complete'. None of the MSDS contained a 'statement of the hazard' and, in general, chronic health effects were inadequately addressed. A sample MSDS for HCFC-123 refrigerant, prepared in accordance with the National Commission's National Code of Practice for the Preparation of Material Safety Data Sheets is included at Appendix 1. This sample MSDS was compiled from the information made available for assessment and is intended for guidance purposes only. Under the National Commission's National Model Regulations for the Control of Workplace Hazardous Substances, manufacturers and importers are responsible for preparing MSDS and ensuring that information is accurate and up-to-date. Labels Two labels for HCFC-123 and two (proposed) labels for HCFC-blend-containing extinguishants (fixed and portable) were submitted for assessment. Labels were assessed for requirements under the National Commission's National Code of Practice for the Labelling of Workplace Substances. None of the labels for HCFC-123 (refrigerant) or extinguishant blends included the signal word 'hazardous' or 'harmful'. Only one of the refrigerant labels included information on health risks, first aid, spills and leaks, and neither contained precautions for firefighting. The label for the fixed extinguishant complied only with substance identification and ADG Code classification requirements. The label for the portable extinguisher did not comply in any respect with the National Commission's labelling code of practice. Exposure standards Industry-set exposure limits The current industry-set exposure limits are a TWA Allowable Exposure Limit (AEL) for HCFC-123 in workroom air of 30 ppm (187 mg/m3) and an Emergency Exposure Limit (EEL) currently set at 1000 ppm with a ceiling limit of 2500 ppm. There are no industry exposure limits for atmospheric levels of HCFC-123 arising from the use of HCFC-blend fire extinguishants. However, the Australian/New Zealand Standard (AS/NZS 4214.5) for NAF S-III total flooding systems recommends a 'health-based' maximum exposure concentration of 10.5% in 'normally occupied areas'. Regulatory standards There is no Australian or overseas occupational exposure standard for HCFC-123. The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has recently classified HCFC-123 as a Group IIIB carcinogen, that is, it is suspected of having carcinogenic potential. The setting of a TWA (8 hours) occupational exposure standard would provide guidance for industry. The setting of a short term exposure limit (STEL) is not considered appropriate for HCFC-123. Health surveillance There are no formal requirements for health surveillance programs for workers exposed to HCFC-123. The risk assessment for HCFC-123 indicates that under anticipated conditions of use, risks of adverse health effects to workers are likely to be low. In addition, atmospheric monitoring is considered sufficient to evaluate exposure to HCFC-123 and, therefore, routine health surveillance is not recommended. Environmental risk assessment Aquatic fate Significant amounts of HCFC-123 are not expected to enter aquatic environments because of limited solubility and high volatility. Spills to water would largely evaporate as HCFC-123 is not readily biodegradable and resists chemical degradation. HCFC-123 has the potential to contaminate groundwater. However, it is reluctant to dissolve and degases readily from solution even at concentrations well below the solubility limit. Furthermore, the isomer HCFC-123a has been shown to undergo reductive dechlorination in methanogenic landfill leachate, suggesting that HCFC-123 would also undergo anaerobic biodegradation. Hydrophilic degradation products of atmospheric HCFC-123, notably trifluoroacetic acid (TFA), may precipitate in rain and enter aquatic environments. TFA is expected to become associated mainly with the aquatic compartment as the sodium salt underwent minimal sorption in three different soils. TFA may persist in aquatic environments as no biodegradation was observed in standard biodegradation testing on its sodium salt, even though the test was continued for 77 days. Recent findings that trace amounts of TFA can be degraded, by reductive defluorination under anoxic conditions and by decarboxylation under oxic conditions, imply that microbial sinks do exist for the elimination of TFA. However, the significance of these processes remains uncertain, and it has been suggested recently that TFA could accumulate within a few decades to potentially toxic levels in some wetlands where evaporation is high and water seepage limited. Atmospheric fate Because of its volatility, any HCFC-123 released to the environment will partition almost entirely to the atmosphere, where its main mode of degradation will be reaction with tropospheric hydroxyl radicals. It has been estimated that around 90% of emissions will be so degraded, leading to an estimated atmospheric lifetime at steady state of 1.5 years. Trifluoroacetyl chloride, the main degradation product (98% in laboratory testing), is expected to be removed from the troposphere by dissolution in cloud water, hydrolysis to TFA and precipitation in rain. As a minor removal pathway, photolysis to carbonyl fluoride may occur in the upper troposphere, with further photolysis to hydrogen fluoride in the stratosphere. Effects on aquatic organisms HCFC-123 appears to range from slightly toxic to practically nontoxic to fish, water fleas and algae. The main acute effect noted at concentrations below 100 mg/L was anaesthesia, followed generally by recovery as the HCFC-123 degassed from solution. Fish died when exposed to concentrations above 100 mg/L. Chronic effects on aquatic organisms would not be expected as HCFC-123 is clearly non-persistent in water, even at concentrations below the solubility limit. Atmospheric effects The dominant concern associated with chlorinated or brominated hydrocarbons is that they can transport these halogens to the stratosphere where they catalyse the destruction of ozone. Model calculations indicate that the ozone depletion potential (ODP) of HCFC-123 is around 2% of those for CFC-11 and CFC-12, which have ODPs of about one. HCFC-123 blends will replace Halon 1211 and Halon 1301, which have ODPs of five and 12 respectively. Like other halocarbons, HCFC-123 contributes to the global warming potential (GWP) of the atmosphere. However, its atmospheric lifetime is short at less than two years, and its GWP is only 2% of that for CFC-11 and less than 1% of that for CFC-12. Hazard evaluation and management HCFC-123 exhibits no more than slight toxicity to wildlife, but may elicit biological effects indirectly by impacting on stratospheric ozone, thereby increasing the amount of harmful ultraviolet radiation reaching the Earth's surface. Degradation products of HCFC-123 are not expected to present a hazard to the environment. The persistence of the degradation product TFA raises concerns for its accumulation in the environment, possibly within a few decades in certain wetlands where evaporation is high and water seepage limited. The recent discovery of aerobic and anaerobic sinks for TFA is promising, but further research in this area will need to be monitored. While the ODP is reduced by a factor of 50 relative to CFC-11, it remains finite. Accordingly, HCFC-123 is only considered acceptable as an interim replacement for fully halogenated CFCs and halons in cooling and firefighting applications. Products based on HCFC-123 represent a major hazard reduction compared with CFCs and halons because of the major reduction in ODP, but are only acceptable during transition to ozone benign replacements. Adherence to industry codes of practice is expected to minimise environmental emissions of HCFC-123 arising from current use, handling and disposal. To ensure an orderly phase-out, the Commonwealth Government proposes controls on the importation and manufacture of HCFCs at a level that will meet the needs of existing owners of HCFC-based equipment, but will not encourage the use of HCFCs where alternative technologies are available. The controls will be administered under the Ozone Protection Act 1989 (Cwlth). The proposed phase-out timetable meets Australia's current obligations under the Montreal Protocol and will be responsive to future changes to it. Regulations will gradually reduce the quantity of HCFCs imported and manufactured until 2015, with a small quantity available for the maintenance of long life commercial air conditioning equipment until 2030. The policy for control of HCFC emissions in Australia proposes the extension of some existing State and Territory controls on CFCs and halons, including adherence to industry codes of practice and the banning of unnecessary emissions to include the control of future emissions of HCFCs. Conclusions In Australia, HCFC-123 is currently being used as a replacement for CFC refrigerants in the air conditioning industry and in HCFC extinguishant blends as replacements (in both portable and fixed extinguisher systems) for halons in the fire protection industry. As with CFCs, HCFCs are being phased-out under the Ozone Protection Act 1989 due to their ozone depleting potential. The main sources of occupational and environmental exposure to HCFC-123 are release during chiller maintenance and firefighting. Data on human health effects from HCFC-123 exposure are limited. However, adequate data exist from animal studies which, when considered with available human health effects information on structural analogues of HCFC-123, provide a basis for characterising human health risks from acute and chronic exposure to HCFC-123. Acute effects from inhalation of HCFC-123 are CNS depression, cardiac sensitisation and asphyxiation and possible liver damage. In animals, the most sensitive acute effect is hepatotoxicity which was seen in guinea pigs at 1000 ppm, the lowest dose tested. Data on structural analogues indicate that humans are likely to be less sensitive than guinea pigs with respect to acute liver toxicity. Occupational exposure to acutely toxic levels of HCFC-123 would not be expected for chiller maintenance workers, as monitoring data indicate that peak levels do not usually exceed a few hundred parts per million. Levels of HCFC-123 (in the breathing zone) have been measured at around 1000 ppm from indoor discharge of portable fire extinguishers. Although such a level of exposure is unlikely to present a health risk, exposure to other HCFC ingredients will increase the risk. Health risks for professional firefighters are low due to the deployment of personal protection. However, the risk of acute effects may be significant for other workers using portable extinguishers, particularly where discharge takes place in confined work areas. Occupational exposure to extinguishant from fixed (total flooding) systems is not expected to occur under normal discharge conditions. Additional health risks may arise from acute exposure to toxic substances (including phosgene and hydrogen fluoride) formed from both extinguishant combustion and reaction with burning materials. Chronic effects from inhalation of HCFC-123 are possible damage to liver, pancreas and testes, including a potential carcinogenic hazard in these organs. In view of the available mechanistic and genotoxicity data, a threshold approach was considered appropriate for characterising chronic health risks from exposure to HCFC-123. Animal studies indicate that the NOAEL for chronic effects is 100 ppm of HCFC-123. Chiller maintenance workers, although potentially exposed on a routine basis, are unlikely to be exposed to levels (airborne) in excess of 5 ppm (TWA), and hence the risk of chronic health effects is considered low. Similarly, chronic exposure to HCFC-123 extinguishant blends is likely to be minimal due to: (a) deployment of personal protective equipment by professional firefighters; and (b) the infrequency of exposure to extinguishant discharges for other worker populations, and hence the risk of chronic effects is likely to be negligible. Although it has been demonstrated that compliance with existing control measures as described in the relevant codes of practice and standards for the air conditioning industry results in TWA HCFC-123 exposure levels of less than 5 ppm, and generally less than 1 ppm, peak levels in excess of 100 ppm may be encountered during certain maintenance operations. Emissions of HCFC-123 could be controlled further by paying particular attention to engineering controls and safe work practices recommended for refrigerant transfer and leak testing operations. Adherence to relevant codes of practice and standards for both fixed and portable extinguisher systems will also contribute significantly to controlling inadvertent emissions and accidental exposures. In general, the codes of practice and standards reviewed (for both refrigerants and extinguishants) contain sufficient information on engineering controls and safe work practices. Labels and MSDS were generally below National Commission requirements. Labels in particular were lacking adequate risk, safe use and first aid information. It is recommended that an occupational exposure standard (TWA) for HCFC-123 be developed by the National Commission. HCFC-123 is unlikely to present a public health hazard, except as a consequence of a catastrophic accident (for example, a major chiller failure) or exposure during extinguishant discharge. The likelihood of such events is very small and the scale and duration of any resultant public exposure is expected to be low. HCFC-123 is not directly toxic to flora or fauna. Indirect biological effects are possible due to the contribution of HCFC-123, albeit small, to ozone depletion. A possibility exists that the degradation product TFA may accumulate within a few decades to potentially toxic levels in certain wetlands. Recent findings suggest that TFA degrades in aerobic and anaerobic environments, but further research on this aspect should be monitored. Recommendations Classification In accordance with the National Commission's Approved Criteria, HCFC-123 is considered to be a 'hazardous' substance. With respect to the available health effects data and in accordance with the health effects criteria detailed in the Approved Criteria, HCFC-123 should be classified as: CARCINOGEN-CATEGORY 3. HCFC-123 falls into sub-category 3(b), signifying that further studies are necessary before a final decision on the carcinogenic status can be made (see section 16.9, 'Further studies'). Products or preparations containing more than 1% by weight of HCFC-123 should also be classified as 'hazardous' or 'harmful'. However, products containing other hazardous chemicals (for example, fire extinguishant blends) should be classified taking into account the health effects of all ingredients. Provision of information As HCFC-123 is a hazardous substance, employers and suppliers should be aware of their obligations to provide information about the hazards of the chemical, such as MSDS and labels. Details of these obligations, consistent with employers' general duty of care, are provided in the National Commission's National Model Regulations for the Control of Workplace Hazardous Substances. Material safety data sheets The National Commission's National Code of Practice for the Preparation of Material Safety Data Sheets provides guidance for the preparation of MSDS. A survey of the MSDS for HCFC-123 and HCFC-123-containing extinguishant products indicated that some were below the standard considered adequate under this code of practice. The following important items were not included in the majority of MSDS:
It is recommended that manufacturers and importers review and upgrade the MSDS in accordance with the National Commission's National Code of Practice for the Preparation of Material Safety Data Sheets and ensure that the above items are addressed . A 'sample' MSDS for HCFC-123 refrigerant is provided at Appendix 1 for guidance. Labels The National Commission's National Code of Practice for the Labelling of Workplace Substances provides guidance for the labelling of workplace hazardous substances. It is recommended that labels be reviewed and upgraded to include risk and safety phrases, first aid procedures, emergency procedures and conform to ingredient disclosure requirements-that is, HCFC-123 as a 'Type I' hazardous ingredient should be disclosed on the label when present in a mixture above 1% w/w . Consistent with its classification, the following risk and safety phrases are recommended for HCFC-123:
HCFC-containing extinguishants containing other hazardous ingredients should be classified and labelled accordingly. Risk phrase R40 will apply to all extinguishant blends containing HCFC-123 above 1% w/w. Appropriate safety phrases should be selected from the National Commission's National Code of Practice for the Labelling of Workplace Substances. Labels for portable fire extinguishers containing HCFC-123 should take into account the requirements of the National Commission's National Code of Practice for the Labelling of Workplace Substances. Collaboration with the Fire Protection Group of Australian Standards is encouraged with respect to this issue. Labels for portable fire extinguishers containing HCFC-123 should contain a prominent warning about using the extinguisher in a confined space and include the appropriate test ratings according to Australian Standard AS 1850, that is, Class A to Class F. Training and education Guidelines for the induction and training of workers potentially exposed to hazardous substances are provided in the National Commission's National Model Regulations for the Control of Workplace Hazardous Substances and National Code of Practice for the Control of Workplace Hazardous Substances. Workers potentially exposed to HCFC-123 need to be trained in safe work practices for handling, storage, transportation and disposal of the chemical. For chiller maintenance technicians, training provided at induction should include relevant information from the Australian Refrigeration and Air Conditioning Code of Good Practice, the Australian Standard for Refrigerating Systems and the MSDS, and should be reinforced at regular intervals. In particular, training should provide information on adverse effects from exposure to HCFC-123 and should address appropriate control and safety measures required to minimise both occupational and environmental exposure. For extinguishant maintenance workers, training provided at induction should include relevant information from appropriate Australian Standards (including AS/NZS 1851.12) and the FPIAA Australian Code of Practice for Design, Installation, Inspection and Testing of Gaseous Fire Extinguishant Systems. For personnel working in areas protected by portable HCFC-blend extinguishers, employers should ensure that adequate training is provided on the safe use of these extinguishants, which should include adequate information on acute health hazards (including first aid) and appropriate warning and instruction on extinguishant discharges in confined working areas. Occupational control measures Under the National Commission's National Model Regulations for the Control of Workplace Hazardous Substances and National Code of Practice for the Control of Workplace Hazardous Substances, control measures must be implemented to minimise health risks during handling and use of hazardous substances. With respect to HCFC-123, control measures should be implemented to minimise incidental and accidental exposure to refrigerant and extinguishant vapour. With regard to the use of HCFC-123 as a refrigerant, it is recommended that:
Exposure standard It is recommended that an occupational exposure standard for HCFC-123 be developed by the National Commission. From the information made available for assessment it is recommended that the TWA exposure standard is based on the NOAEL for liver effects, determined at 100 ppm (0.6 g/m3) HCFC-123 in repeat dose animal studies. This is considered a reliable NOAEL derived from a well-conducted two-generation reproductive study, and supported by other mechanistic and toxicity studies. There is no indication that a STEL or 'skin notation' should apply. Health surveillance It is considered that HCFC-123 is unlikely to adversely affect the health of workers under the present conditions of use. In addition, air monitoring techniques are considered to provide an accurate estimate of exposure. Therefore, it is recommended that HCFC-123 not be considered for addition to Schedule 3 of the National Commission's National Model Regulations for the Control of Workplace Hazardous Substances. Under regulations introduced in Commonwealth, State and Territory government jurisdictions in accordance with these model regulations, employers will need to provide health surveillance in workplaces where assessment shows that exposure to HCFC-123 results in a substance-related health effect. Revision of codes of practice and Australian Standards In order to improve the usefulness of the Australian Refrigeration and Air Conditioning Code of Good Practice and the Australian Code of Practice for Design, Installation, Inspection and Testing of Gaseous Fire Extinguishant Systems, it is recommended that consideration be given to revising these documents to provide more complete information on occupational health and safety. Such information may include: health hazards; precautions for use, for example, specifications for personal protective equipment; and safe handling information, for example, requirements for storage and disposal of HCFC refrigerant and extinguishant products. Until Australian Standard AS1677 has been updated, it is also recommended that the ASHRAE Safety Code for Mechanical Refrigeration be used in conjunction with the above-mentioned Australian codes. Based on its health effects, it is recommended that HCFC-123 be classified as a 'Group 2' refrigerant for the purposes of updating Australian Standard AS 1677. It is recommended that future revisions of the Australian Standards for portable (Australian Standard AS 1841.1) and gaseous (fixed) extinguishers (Australian/New Zealand Standard AS/NZS 4214.5) take into account the National Commission's National Code of Practice for the Labelling of Workplace Substances. Transport It is recommended that the Federal Office of Road Safety's Advisory Committee for the Transport of Dangerous Goods (ACTDG) consider HCFC-123 for classification as a Class 9 Dangerous Good in view of the following hazardous properties:
Environmental protection Use of HCFC-123 to replace CFCs in cooling applications is recommended on environmental grounds, since the ODP and GWP of the replacement substance are typically some 50 times lower than those for CFCs. Similarly, the use of blends containing HCFC-123 extinguishants to replace halons in certain firefighting applications is recommended because of the major reduction in ODP. Users should be aware that HCFC-123 is not environmentally innocuous, and that its use will only be acceptable as an interim measure pending development of alternatives with lower ozone depletion potential. Australia's ratification of the Copenhagen Amendment to the Montreal Protocol requires that domestic consumption of HCFCs be frozen in 1996, followed by reductions in use of 35% by 2004, 65% by 2010, 90% by 2015, 99.5% by 2020 and total phase-out by 2030. In view of the phase-out schedule required by the Copenhagen Amendment to the Montreal Protocol, manufacturers of equipment requiring HCFCs, including HCFC-123, should investigate options for converting to other forms of refrigeration and fire protection technology. Manufacturers, distributors and users must minimise atmospheric emissions of HCFC-123 by adhering to the Australian Refrigeration and Air Conditioning Code of Good Practice and the FPIAA's Code of Practice. Existing legislative controls on halons, including requirements for their recovery and safe disposal, should be extended to HCFCs. Further studies Toxicological studies Mechanisms of carcinogenicity Ideally, further research should concentrate on establishing the relevance of the composed related benign tumours (particularly cholangiofibromas and pancreatic adenomas) to humans. The available mechanistic data indicate that the rat may not be the most suitable animal model for characterising potential carcinogenic effects of HCFCs in humans. For pancreatic tumour studies, the BOP hamster model has been considered more relevant (to humans) because of tumour type similarities and with respect to peroxisome proliferation, the guinea pig is considered a more suitable model for humans. While it is appreciated that life-time studies in these species may not be a viable option for a number of reasons, for example, the fact that HCFC-123 is only being used as an interim alternative to CFCs, it is recommended that efforts be made to further elucidate the mechanisms of tumours induced by HCFC-123 in rats, in an attempt to characterise potential human hazards. Further studies might include:
Reproductive effects Experimental evidence from a two-generation reproductive toxicity study in rats indicates that reduced weight gain and delayed sexual maturation in offspring may result from HCFC-123 transfer through breast milk, that is, a lactational effect. This could be investigated further by: establishing whether this effect is due to a reduced intake of breast milk by pups in exposed groups; and analysing breast milk to establish whether HCFC-123 is present in potentially toxic levels. Monitoring studies It is recommended that monitoring studies be carried out to establish potential airborne levels of total HCFCs from discharge of HCFC blends from portable (hand-held) extinguishers (3-5 kg), particularly in confined working areas. Quantitative information on yields of thermal degradation products of HCFC-123 and HCFC-blend extinguishants under high temperature conditions would assist in characterising the acute health risk or hazard from exposure.
|
.................................
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Home : Publications : Car : Pec : Pec4 |
| http://www.nicnas.gov.au/publications/car/PEC/PEC4/Summary_Report.asp | |
| © Copyright Commonwealth of Australia | Privacy | Disclaimer | Last Modified: 8/02/2012 |
