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Priority Existing Chemical Assessment Reports - 2-Butoxyethanol in Cleaning Products
Introduction The chemical 2-butoxyethanol (2-BE), CAS no. 111-76-2, was declared by the Minister for Industrial Relations as a priority existing chemical (PEC) under the Industrial Chemicals (Notification and Assessment) Act 1989 (Cwlth) (the Act) by notice in the Chemical Gazette of 5 April 1994. The declaration was specific for the use of 2-BE in cleaning products. In accordance with the Act, manufacturers and importers of 2-BE for its use in cleaning products, and importers of cleaning products containing 2-BE, were obliged to apply for the assessment of 2-BE as a PEC. Information for the assessment was obtained from several sources, including the applicants, overseas manufacturers and regulatory authorities, local formulators, end-users, and the scientific literature. Material Safety Data Sheets and labels for many of the cleaning products and information about the formulation process and worker exposure were supplied by formulators in response to a questionnaire. Applicants
Chemical identity 2-BE is listed on the Australian Inventory of Chemical Substances (AICS) as ethanol, 2-butoxy-. Its IUPAC name is ethylene glycol butyl ether and it is also known as butyl ethoxol, butyl glycol and ethylene glycol monobutyl ether. Trade names for 2-BE include Butyl Cellosolve, Butyl Icinol, Butyl Oxitol, Dowanol EB and Ektasolve EB. The known trade names of cleaning products in Australia which contain 2-BE are listed in the Full Public Report. Physical and chemical properties 2-BE is a colourless liquid with an unpleasant odour. The odour threshold is 0.10 ppm. Table 1 - Physical and Chemical Properties
2-BE is miscible with water and most organic solvents. It undergoes reactions typical of glycol ethers, including oxidation, acetal formation and esterification. It is unlikely to undergo hydrolysis. Conversion factor (for vapour): 1 ppm = 4.9 mg/m3 (20° C, 1014 hPa). Use Use of 2-BE in cleaning products is one of several uses in Australia. 2-BE is manufactured at one plant in Australia and is also imported for formulation into cleaning products. A number of cleaning products containing 2-BE are also imported. Approximately 1000 tonnes of 2-BE are formulated into cleaning products in Australia per year. During the assessment period, 82 formulators and 434 cleaning products containing 2-BE were identified. In the products, which are mostly aqueous, the 2-BE content ranges from less than 0.1% to 94%. Depending on the end-use, most cleaning products contain other ingredients, for example, surfactants, sodium hydroxide, phosphoric acid, ammonia and other glycol ethers. Based on information received during the assessment, the main uses in Australia of cleaning products containing 2-BE are tabled below. Table 2 - Main Types of Cleaning Products
< denotes 'less than' Many of the products classed as surface cleaners are multi-purpose cleaners, for example, they could be used in a variety of applications such as floor and wall cleaning, floor stripping, oven cleaning, grease trap cleaning, engine degreasing, vehicle washing and laundry pre-spraying. A number of products could be used in hot or cold water pressure cleaning machines. Cleaning products listed above under 'others' included aluminium cleaner/brighteners, electrical cleaning solvents and toilet/bathroom cleaners. Cleaning products can be applied by a number of different methods, including washing, wiping, spraying, mopping, brushing, soaking and by machine. In most cases, the commercial cleaning product needs to be diluted with water prior to application, the dilution factor being dependent on the type of surface, soil loading and the type and method of application. In some cases, end-users use hot water for dilution. Occupational exposure Workers may be exposed to 2-BE during its manufacture and during the formulation and use of cleaning products containing the chemical. Exposure may be short-term, for example, during spray application of a cleaning solution, or prolonged, for example, washing cars throughout a shift. For 2-BE in cleaning products, good quality monitoring data were limited, particularly for formulation. The atmospheric monitoring data available were TWA measurements, although some short-term monitoring, for example, 15 minutes sampling, was conducted during specific cleaning operations. Very little data for dermal exposure were available. Using the available data as much as possible, estimates of total (inhalation plus dermal) exposure of workers to 2-BE during manufacture, formulation and cleaning were calculated. As 2-BE is not bioaccumulative and the critical effect, haemolysis, is transient, the exposure estimates were calculated for daily doses (up to 8 hours) rather than long-term exposures. The estimates are considered to be 'feasible' worst-case estimates, as they describe high end or maximum exposure in 'feasible but not unrealistic' situations. 2-BE is manufactured at only one plant in Australia. The process is enclosed and regular air monitoring has demonstrated that mean TWA air concentrations are less than 1 ppm. Exposure is low, with the estimated dose not expected to exceed 1.4 mg/kg/day. This estimate is based on data for non-routine operations such as maintenance and drum filling. As the manufacturing process is enclosed, and control measures are in place, exposures for routine process work would be much lower than 1.4 mg/kg/day. Worker exposure to 2-BE during formulation is expected to be quite variable due to differences in process conditions (e.g. the process may be enclosed or relatively open) and the duration of exposure (some formulators produce cleaning products containing 2-BE infrequently or in small quantities). From the assessment of exposure, estimates are not expected to exceed 9.5 mg/kg/day. However, approximately 70% of formulators spend less than 3 hours per week on the production of cleaning products containing 2-BE, and approximately 70% of cleaning products contain less than 10% 2-BE. So the exposures for most formulation workers would not be expected to exceed 1.0 mg/kg/day. A large number of cleaning products containing 2-BE are marketed in Australia, with thousands of workers potentially exposed to the chemical. Worker exposure varies considerably due to factors such as the type of work, method of application, exposure time and concentration of 2-BE in the cleaning solution. Exposure, particularly inhalational exposure, will be increased during spray application or during other operations which may generate vapour or aerosols. Worker exposures are not expected to exceed 13.7 mg/kg/day. However, given that approximately 70% of cleaning products contain less than 10% 2-BE, and that most are diluted to a working strength below 1%, exposure for most workers using cleaning products would not be expected to exceed 1.6 mg/kg/day. Using the average exposures available from monitoring data, typical exposures during the use of most cleaning solutions containing 2-BE would be less than 1 mg/kg/day. The exposure assessment has shown that the dermal exposure component of total worker exposure to 2-BE may contribute up to 50% of the daily dose, especially with prolonged (5-8 hours) use of cleaning products containing 10% or more 2-BE. Health effects Kinetics and metabolism 2-BE is well absorbed via the inhalational, oral and dermal routes. Absorption studies in various species, including humans, have shown that 2-BE is rapidly absorbed through the skin, including absorption from aqueous solution. Dermal studies in humans and human skin specimens indicate that the dermal absorption rate was most likely in the order of 0.2 mg/cm2/h. The respiratory uptake in volunteers in inhalational studies was approximately 57-78% of the inspired amount. Human studies indicate that dermal absorption of vapour is approximately 20% of the total vapour uptake. Following absorption, 2-BE is widely distributed throughout the body. Studies in animals and humans have indicated that the major metabolic pathways of 2-BE are similar in various species. 2-BE is metabolised mainly to 2-butoxyacetic acid (BAA), which is formed by oxidation by alcohol/aldehyde dehydrogenase. Smaller amounts of the glucuronide and sulfate conjugates and ethylene glycol can be formed by other metabolic pathways. In human studies, the glutamine conjugate of BAA has been detected in urine following exposure to 2-BE, which suggests that there is an additional detoxification pathway in humans. 2-BE is removed from the blood with an elimination half-life of approximately 40-80 minutes. The major metabolite BAA is rapidly excreted in urine with a urinary excretion half-life of approximately 3-6 hours. In human studies, wide variations in absorption and excretion rates between subjects have been found. Human health effects Exposure to 2-BE vapour may result in irritation of the eyes, nose and throat, headache and nausea. In controlled studies in volunteers, nose and eye irritation were observed at 113 ppm, nausea and headache at 100 ppm, but no adverse effects were noted at 50 ppm. Workers using 2-BE cleaning products have reported respiratory irritant effects, nausea, headache and tiredness, however the atmospheric levels were unknown. Contact dermatitis has been reported in a few cases by persons using cleaning products containing 2-BE, but controlled studies resulted in slight or no skin irritation. In a patch test in volunteers, 2-BE was not a skin sensitiser. Haemolytic effects have only been observed in humans who have ingested large quantities (30 - 60g) of 2-BE. This is consistent with the results of a number of in vitro studies which found that human red blood cells, compared with most other species tested, were much less susceptible to haemolysis by BAA, the major metabolite and principal agent of haemolysis. The ingestion of large quantities of 2-BE may result in coma, metabolic acidosis, shock and respiratory distress. Effects in experimental animals and in vitro test systems The main effect observed in both acute and repeated dose animal toxicity studies is haematotoxicity, with the principal haemolytic agent being BAA. The species differences in susceptibility to this effect are considerable, with rats and mice the most susceptible, rabbits less susceptible and humans and guinea pigs the least susceptible. The acute toxicity of 2-BE is moderate by all routes of exposure and is, in general, higher than other glycol ethers. The oral LD50 (rat) is 530-3000 mg/kg, dermal LD50 (rabbit) is 100-610 mg/kg, and inhalational LC50 (rat) is 2.2-2.4 mg/L (450-486 ppm) (4h). Death was generally caused by narcosis or respiratory failure. Haemolytic effects were observed in most acute studies, with associated effects on the kidney and liver. Acute dermal studies show that 2-BE is readily absorbed through the skin. 2-BE is a severe eye irritant. Results of skin irritation studies are conflicting; however, 2-BE is considered to be a mild to moderate skin irritant in test animals. The results of one sensory irritation study in mice indicate that 2-BE vapour may be irritating to the nose and throat. Skin sensitisation studies were negative, and immunotoxicity studies in the rat and guinea pig did not result in any significant effect on the immune response. The critical effect in repeated dose animal studies by all routes of exposure is haematotoxicity. The main signs of toxicity at high doses include anaemia (decreased red blood cell count and haematocrit, decreased mean cell haemoglobin concentration and increased mean cell volume) and haemoglobinuria due to haemolysis of the red blood cells. At lower doses, haemolytic effects are transient, generally occurring during the first days of exposure only. There is some evidence of haemopoiesis occurring as a compensatory mechanism, such as spleen hyperplasia. In addition, this transience could be due in part to the replacement of older red blood cells with younger, more resistant ones, as in vitro test results indicate that younger red blood cells are more resistant to haemolysis than older ones. Haematotoxicity in rats appears to be age-related, with the effects more severe in older rats. In vivo studies indicate that there are significant species differences in the susceptibility to the haemolytic effect of 2-BE. Rats appear to be the most sensitive species. In vitro studies have confirmed the species differences observed in in vivo studies. In particular, the studies have shown that human red blood cells are at least ten times less sensitive than rat red blood cells to the haemolytic effects of BAA. Studies demonstrated that haemolysis is preceded by swelling, increased osmotic fragility and decreased cell deformability of red blood cells. Therefore, the evidence indicates that the haemolytic effects of 2-BE are a result of changes to the red blood cell membrane rather than effects on the bone marrow. In a 90-day inhalational study in rats, the no observable adverse effect level (NOAEL) was 24.6 ppm. In a 90-day dermal study in rabbits, the NOAEL was 150 mg/kg/day. In a 90-day drinking water rat study conducted by the US National Toxicology Program (NTP), the NOAEL was 129 mg/kg/day for male rats, but no NOAEL could be established for the females as slight anaemia was observed at the lowest dose (82 mg/kg/day). Effects other than haemolysis which have been observed in repeated dose studies include changes to the liver, kidney, spleen and thymus, with these effects considered secondary to haemolysis as they are seen at levels at or above haematotoxic doses. In fertility studies, minor changes in sperm concentration and the oestrous cycle were noted in a drinking water rat study but adverse effects have been observed only at or above doses which are toxic in other respects. In a two-generation study in mice, significant adverse effects were observed only at very high dose levels which caused severe maternal toxicity. These results for 2-BE are in contrast to the lower molecular weight homologues, 2-methoxyethanol and 2-ethoxyethanol, which both cause testicular degeneration. In other reproductive studies, developmental effects were observed only at maternally toxic doses. No evidence of teratogenicity was observed in any studies, again in contrast to 2-methoxyethanol and 2-ethoxyethanol. 2-BE has tested negative in a wide variety of well conducted in vitro assays, including gene mutation, chromosomal aberration and DNA effect assays. These assays were generally conducted at both cytotoxic and non-cytotoxic doses. In a recent study, 2-BE was a weakly positive inducer of gene mutations, sister chromatid exchanges and aneuploidy in V79 cells at high doses. 2-BE was negative in an in vivo mouse micronucleus assay. Based on the available data, 2-BE is probably not genotoxic. No 2-year carcinogenicity studies were available but an NTP inhalational study in rats and mice is under way. Risk characterisation (occupational) Critical health effects The critical effects identified for acute exposure to 2-BE are eye and respiratory irritation, with irritation observed in controlled studies at 113 ppm but not at 100 ppm. In most work situations, the risk of irritant effects is low as the concentration of 2-BE is low in most cleaning products and 2-BE has a low volatility. However, the risk may be increased where aerosols are generated, heat is used, or where cleaning products are used in spray form. Based on human evidence, 2-BE is not classified as a skin irritant, but slight irritation may occur after repeated skin contact. It has been demonstrated that skin absorption can occur in the absence of irritation. The critical effect (that is, the most sensitive endpoint) identified in animal studies for repeated or prolonged exposure to 2-BE is haemolysis of the red blood cells. As the effect is transient at lower doses and 2-BE does not bioaccumulate, the effect is considered more of an acute effect than a chronic effect. The lowest reliable NOAEL for haemolysis in the most sensitive species (the rat) is 24.6 ppm (22.5 mg/kg/day) from a 90-day inhalational rat study. From the results of controlled and case studies in humans, animal in vivo studies, and in vitro studies using animal and human red blood cells, humans are less sensitive to the haemolytic effect of 2-BE than rats. For example, increased red blood cell fragility was observed in rats exposed to 54 ppm 2-BE for 7 hours, however, no effect was observed in human volunteers exposed to 195 ppm for 8 hours. In vitro studies indicate that human red blood cells are at least ten times less sensitive than rat red blood cells to the haemolytic effects of BAA, and that the red blood cells of the aged and persons with hereditary blood disorders are not significantly affected by BAA. The risk of haemolytic effects in humans was determined for each scenario by comparing the estimated human exposure with the NOAEL (22.5 mg/kg/day), and then taking into account the following parameters: the human population exposed, the nature and severity of the effect, inter- and intraspecies variability, and uncertainties in the risk assessment process such as the quality and completeness of the database. Risk during manufacture of 2-BE The risk of acute effects and haemolysis is minimal during the manufacture of 2-BE as the process is enclosed, and reported atmospheric levels do not exceed 1.8 ppm. Some exposure may occur during plant maintenance and during drumming off and transference from storage vessels to road tankers, however, these tasks are well-controlled at the manufacturing plant. Risk during formulation of cleaning products In most work situations, vapour and aerosol concentrations are unlikely to be high enough to result in respiratory or eye irritation. However, eye and respiratory irritation may occur in certain work situations where aerosols are generated or where high vapour concentrations occur, for example, during the handling of spills, during maintenance, or if heat is applied. The highest exposure estimated for inhalational and dermal exposure during formulation was calculated to be 9.5 mg/kg/day. For the various scenarios considered (for the formulation of products containing up to 60% 2-BE), the risk of haemolytic effects in workers exposed to 2-BE during formulation is minimal. Risk during use of cleaning products In well-controlled work situations, the risk of acute effects in cleaners is of low concern. However, cleaning products containing 2-BE may be used in workplaces where control measures are poor, for example, without adequate ventilation and personal protective equipment, and therefore exposure may be greater. Also, many of the cleaning products are deliberately used in spray form and, in some cases, users are advised to apply heat during dilution of the product. The resultant periodic generation of vapour and/or aerosols may lead to a greater risk of respiratory and eye irritation, particularly in workplaces with inadequate ventilation. Most of the reports of irritation in cleaners have been associated with the use of cleaning products in spray form. The highest dose estimated, for inhalational and dermal exposure during cleaning, was 13.7 mg/kg/day. For the various scenarios considered (for the use of cleaning products containing up to 30% 2-BE), the risk of haemolytic effects in workers exposed to 2-BE during cleaning operations is minimal. Due to the uncertainty in estimating exposure levels, and the possibility that they may exceed the NOAEL, there may be some cause for concern for workers using cleaning solutions containing high concentrations of 2-BE (greater than 30%) for prolonged periods, for example, 8 hours, in situations where control measures are poor. Areas of concern From the risk assessment, there may be concern for the health of workers in some work situations where exposure to 2-BE may occur. There may be a risk of eye and respiratory irritant effects, headache and nausea. Consequently, there is concern for the health of workers, in relation to irritant effects and headache and nausea, in the following situations:
The risk of adverse health effects is greater for any of the above situations when accompanied by poor work practices. For the exposure scenarios considered in the assessment, the risk of haemolytic effects in workers is minimal. Based on the risk assessment of cleaning solutions containing 30% 2-BE, there is a concern in situations where there is a prolonged exposure, particularly dermal exposure, to solutions containing 30% or more 2-BE. Hazard communication Material Safety Data Sheets In accordance with the National Code of Practice for the Preparation of Material Safety Data Sheets (MSDS Code), MSDS must be provided for all hazardous substances. As 2-BE is classified as a hazardous substance according to the ASCC Approved Criteria for Classifying Hazardous Substances (see subsection 12.1.1), cleaning products containing 12.5% 2-BE or more must have MSDS. In 1994, prospective formulators of cleaning products containing 2-BE were requested to reply to a questionnaire and to send a copy of the MSDS and label for each of these products. The responses to the questionnaire identified 82 formulators and 434 cleaning products containing 2-BE and 409 MSDS were submitted. A representative sample was assessed, with the specific objective to qualitatively assess the adequacy of information about 2-BE in the MSDS in terms of compliance with the MSDS Code. In particular, specific health effects data and safe handling precautions were assessed. At the time of the survey in 1994, no State or Territory had enacted their legislation for workplace hazardous substances and the revised MSDS Code and Approved Criteria for Classifying Hazardous Substances had only been published earlier that year. As a considerable time has elapsed since receipt of the MSDS (late 1994), a random re-sample of MSDS took place in April 1996. The assessment indicated that a high percentage of the MSDS conformed to the format recommended in the MSDS Code. However, a number of deficiencies were noted, including deficiencies in the provision of specific information about 2-BE. Deficiencies in the MSDS were noted in the following areas:
The assessment of MSDS was not altered significantly by the re-sample of MSDS in April 1996. The only major change noted was inclusion of a statement of hazardous nature on a large number of updated MSDS. A sample MSDS for 2-BE, prepared in accordance with the MSDS Code, is provided in this report as an Appendix. The sample MSDS, prepared from information obtained for the assessment of 2-BE, is for guidance purposes only. Under the National Model Regulations, manufacturers and importers have the responsibility to compile their own MSDS and ensure that the information is up-to-date and accurate. Labels Products for domestic end-use are covered by the Standard for the Uniform Scheduling of Drugs and Poisons (SUSDP) and need to comply with SUSDP labelling requirements. Under the SUSDP, products containing more than 10% 2- BE are schedule 6 poisons and must be labelled accordingly. After 1993, industrial products were exempted from the SUSDP and should comply with the National Code of Practice for the Labelling of Workplace Substances (the Labelling Code). Hence, industrial products containing 12.5% 2-BE or more should be labelled in accordance with the Labelling Code. Products used industrially and domestically need to comply with both codes. Information was received on 434 cleaning products containing 2-BE. Labels were supplied for 389 of these products. They were assessed for compliance with some of the labelling requirements of the SUSDP and the Labelling Code, in particular, those requirements relating to safety directions/phrases and risk phrases and ingredient statements relating to 2-BE. In addition, labels which specified spraying as a method of application were examined for the presence of any safety statements related to inhalation of vapour or provision of ventilation. Most cleaning products containing 2-BE are used industrially but, at the time of the survey in 1994, most companies had not yet updated their labels to meet the requirements of the relatively new Labelling Code. Thus a large proportion of the products were labelled according to SUSDP requirements. Firstly, many of the labels for products containing more than 10% 2-BE did not comply fully with SUSDP requirements. Secondly, few of these labels fulfilled the requirements of the Labelling Code, in particular, the assigning of risk phrases or equivalent statements which may cover hazards not addressed by the designated SUSDP safety directions, for example, acute toxicity. As no label contained the risk phrase R22 or equivalent statement (Harmful if swallowed), it can be assumed that no products containing 12.5% 2-BE or more complied fully with the requirements of the Labelling Code for products that could reasonably be expected to be used in the workplace. Other deficiencies in the labels included the following:
Public health risk In light of the low concentration of 2-BE in most domestic cleaning products containing the chemical and the intermittent use of such products by the public, and provided that normal precautions are taken to avoid skin, eye and inhalational contact, the public health risk posed by cleaning products containing 2-BE is expected to be minimal. Environmental assessment Environmental fate 2-BE will enter the environment via effluent at sites where it is formulated into cleaning products and via the disposal of any wash water used in cleaning processes. The latter is the predominant pathway. Biodegradation studies indicate that 2-BE will be readily degraded by micro-organisms present at sewage treatment plants. Ready biodegradability tests showed that 2-BE achieved a biodegradation rate of greater than 77% after 3 days and 100% after 7 days. A 20-day biochemical oxygen demand test and an OECD 28-day closed bottle test gave 2-BE degradation rates of 75% and 88% respectively. Literature data confirm these results. Any 2-BE that passes through sewage treatment plants and enters receiving waters is likely to remain in the water column until biodegraded by micro-organisms present in the water. Accordingly 2-BE half-lives in surface water range from 4 weeks to 7 days. The complete miscibility of 2-BE in water suggests that volatilisation, adsorption and bioconcentration are not important fate processes. Disposal of waste 2-BE to landfill may result in contamination of groundwater. A Koc of 67 for 2-BE indicates that it will be highly mobile in soil, and unlikely to partition from the water column to organic matter contained in sediments and suspended solids. 2-BE has been detected in aquifers underlying a municipal landfill and a hazardous waste site in the USA. Environmental effects From a considerable body of test results and QSAR calculations, 2-BE can be classified as being practically non-toxic to fish (LC50 greater than 100 mg/L), aquatic invertebrates, sewage micro-organisms, slightly to practically non-toxic to algae (EC50 35 mg/L) and slightly toxic to oysters (LC50 89.4 mg/L). Environmental hazard As noted above, 2-BE will be readily biodegraded by sewerage micro-organisms and by micro-organisms present in receiving waters. With allowance for dilution by waste streams, it is estimated that the concentration of 2-BE in sewage plants will be in the order of ppm. Further dilution in the receiving waters is likely to result in sub-ppm concentrations. Such levels do not constitute a significant environmental hazard, and will be further reduced by biodegradation during sewage treatment. Recommendations The assessment focussed on the use of 2-BE in cleaning products. However, many of the recommendations are applicable to the other uses of 2-BE. Classification ASCC Hazard Classification In accordance with the ASCC Approved Criteria for Classifying Hazardous Substances, and based on an assessment of health hazards, the recommended classification for 2-BE is:
It is therefore recommended to ASCC that the risk phrase 'R36 Irritating to eyes' be added to the classification of 2-BE on the ASCC List of Designated Hazardous Substances. In determining whether a mixture containing 2-BE is hazardous, the following concentration cut-offs apply: 12.5% for R20/21/22 and 20% for R36 and R37. It is recommended that the differences in concentration cut-offs for 2-BE be brought to the attention of the National Drugs and Poisons Scheduling Committee (NDPSC) and ASCC and, notwithstanding policy issues, that consideration be given to harmonising on a cut-off of 10%. SUSDP listing At present, 2-BE is listed on the SUSDP under 'ethylene glycol monoalkyl ethers', and is often listed on labels as such. However, the health effects of the members of this class of chemicals vary significantly, so it is recommended that the NDPSC consider a separate listing for 2-BE. It is recommended to NDPSC that, during consideration of a separate listing, they reconsider the first aid instructions for 2-BE, in particular the standard statement to be used in case of swallowing (see subsection 12.3.2). Dangerous goods classification This report confirms that 2-BE should be classified as 'harmful' by all three routes of exposure under the EC Directive (on which the Australian Approved Criteria are based). The criteria for acute inhalational toxicity are the same under the EC Directive and the UN Recommendations on the Transport of Dangerous Goods (and the ADG Code). Therefore, the recent decision by the UN Committee of Experts on the Transport of Dangerous Goods to delist 2-BE raises concerns regarding possible differences in the application of the criteria and resulting inconsistencies between the EU and UN classifications of 2-BE. Control measures 2-BE is a hazardous substance which is acutely toxic, readily absorbed through the skin and is an irritant to the eyes and respiratory system. In accordance with ASCC National Code of Practice for the Control of Workplace Hazardous Substances exposure to hazardous substances should be prevented, or where that is not practicable, controlled so as to minimise risks to health. Control measures should be implemented in accordance with the following hierarchy of controls. In devising effective control measures for cleaning products containing 2-BE, suppliers and end-users should also consider the hazards of other ingredients in each product, for example, phosphoric acid in rust removers and sodium or potassium hydroxide in oven cleaners. In relation to 2-BE, particular care needs to be given to control measures to minimise inhalational and dermal exposure. It should be noted that 2-BE can be readily absorbed through the skin and absorption can occur in the absence of irritation. Elimination To minimise risks to health, elimination should be the first control option considered. Elimination is the removal of all chemicals from the cleaning process, such as by employing a physical cleaning process or process redesign. Substitution Where elimination of 2-BE from cleaning processes is not practicable, substitution with another chemical or method of application should be considered. Any substitution of 2-BE should be with safer alternatives which have been thoroughly tested and have demonstrated a lower toxicity, irritancy and potential for skin absorption in humans. With a view towards minimising exposure, formulators should consider reducing the 2-BE content in cleaning products. Similarly, it is recommended that methods of application be reviewed by suppliers and end-users, for example, substituting spray use with use as a liquid stream and application and dilution of cleaning products without heat. Engineering controls Formulation It is appropriate that formulators take into account the health and safety hazards of all ingredients in the formulation to arrive at a safe process that will minimise exposure to 2-BE. Accordingly, it is recommended that the mixing and transfer process be enclosed and that 2-BE be added to the mixing vessel in a safe manner, for example, as one of the last ingredients. The mixing and storage tanks should be covered and exhaust fans installed above them if they are not completely sealed. The mixing area should be bunded so that any spills can be confined. The packing line at the point of filling should be enclosed as much as possible, with local exhaust ventilation recommended if complete enclosure is not achievable. Good dilution ventilation in accordance with Australian standards is essential in all production areas, with the ventilation rate capable of being substantially increased in case of emergencies such as spillage. Total loss ventilation is recommended. Cleaning In some workplaces, for example, mechanical workshops, local exhaust ventilation can be used, but in most work situations, for example, in the cleaning of schools and offices, this is not practical. In these cases, dilution ventilation should be used as much as possible, for example, air conditioning, portable fans, open windows and doors. Good ventilation is essential during the dilution and mixing of solutions. Safe work practices Cleaning products should be formulated and applied in a manner which minimises exposure. Recommended safe working practices include:
Personal protective equipment The following personal protective equipment is recommended where occupational exposure to 2- butoxyethanol may occur: butyl or nitrile rubber gloves; protective clothing which includes protection of the arms, legs and feet; and, eye protection when aerosols or vapour may be generated, for example, during handling of large quantities, during dilution, when heat is used, or when splashing may occur; eye protection may also be required when the product is applied as a spray. All personal protective equipment should be in accordance with the relevant Australian standards. Hazard communication MSDS It is recommended that suppliers amend their MSDS where necessary in order to rectify the deficiencies identified in this assessment. Deficiencies in MSDS noted in the assessment indicate that attention needs to be paid to the following:
Labels It is recommended that suppliers amend their labels where necessary in order to rectify the deficiencies identified in this assessment. The assessment of labels showed that a number of products available to consumers were not labelled with the safety directions required by the SUSDP. Products available to the public which contain more than 10% 2-BE must include the following first aid instructions and safety directions on the product label, in accordance with the following labelling standards recommended by the SUSDP for the ethylene glycol monoalkyl ethers (and their acetates). Safety directions:
First aid instructions:
In accordance with SUSDP, the current first aid instruction for ingestion of preparations containing more than 10% 2-BE (listed under ethylene glycol monoalkyl ethers) is 'If swallowed, and if more than 15 minutes from a hospital, induce vomiting, preferably using Ipecac Syrup APF.' As 2- butoxyethanol is a respiratory irritant and a large number of cleaning products which contain 2- butoxyethanol also contain substances which may be corrosive, it is recommended that consideration of the specific formulation be made when developing first aid advice. For example, when products are formulated with a corrosive substance, the induction of vomiting would be contra-indicated and the following instruction would be warranted: 'If swallowed, do NOT induce vomiting. Give water to drink.' The assessment of labels also showed that the labels of cleaning products which are likely to be used in the workplace, and contain 12.5% or more of 2-BE, had inadequate labelling, lacking the designated risk phrases or equivalent statements required by the ASCC National Code of Practice for the Labelling of Workplace Substances. It is therefore recommended that, where necessary, suppliers of products for industrial use amend their labels to conform to the Code. It is also recommended that the following safety phrases be included (if not already covered by equivalent SUSDP safety directions):
For all products which may be used in spray form in the workplace, it is recommended that the following safety phrase be included on the label:
Training and education In accordance with the ASCC National Model Regulations for the Control of Workplace Hazardous Substances, it is recommended that workers potentially exposed to 2-BE be educated about its hazards and be trained in the safe handling of 2-BE and cleaning products containing the chemical. Accordingly, it is recommended that suppliers, formulators and employers adequately educate and train their customers and employees. Specifically, matters which need to be addressed include:
The training and education of workers who use cleaning products containing 2-BE should be in accordance with the elements listed in the ASCC National Code of Practice for the Control of Workplace Substances, and should include specific information about the hazards of 2-BE and the specific precautions required for safe handling. As many cleaners employed are from a non-English speaking background, it is recommended that practical and audiovisual methods be used as much as possible, and that some written material about the hazards of 2-BE and precautions for the safe use of cleaning products containing the chemical be available in languages other than English, for example, a single page facts sheet. Exposure standard It is recommended that ASCC use this assessment report to prepare updated documentation for the occupational exposure standard. It is also recommended that ASCC consider whether the basis of the exposure standard should be haemolytic effects or other effects such as irritation, nausea and headache, as overseas regulatory agencies have adopted a lower standard based on these effects. Biological monitoring and Biological Exposure Index It is recommended that ASCC develop guidelines for biological monitoring (including analytical method, time of sampling, type of specimen, etc.). These guidelines would assist in the further work recommended to investigate skin absorption (see 12.7.2) and provide assistance to medical practitioners investigating possible exposures to 2-BE. In developing guidelines for biological monitoring and following the further study to investigate the extent of skin absorption, ASCC should consider whether it is appropriate to establish a Biological Exposure Index (BEI). Disposal It is recommended that waste 2-BE not be disposed of to landfill because of its high mobility, low abiotic degradation and its demonstrated ability to leach into groundwater from landfills in the USA. Preferred disposal options are incineration, recycling or removal by a licensed reclaimer. Health hazards Case reports It is recommended that instances of adverse health effects after exposure to 2-BE be fully documented and investigated by the employer and that the cases be reported to the Director, Chemicals Notification and Assessment at Worksafe Australia. Further testing A number of gaps were identified in the knowledge base regarding the health effects of 2-BE, including:
Skin absorption is a significant route of exposure and there is a degree of uncertainty in the estimates of dermal exposure in this assessment. It is therefore recommended that a study be conducted, including biological and atmospheric monitoring, to more thoroughly understand the extent of skin absorption of 2-BE for workers in the cleaning industry. It is noted that a 2-year inhalational study in rats and mice is currently being conducted under the NTP, and an epidemiological study in workers exposed to glycol ethers, including 2-BE, is under way in France. These studies will be reviewed when available as a secondary notification. |
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