Moving gas cylinders in your workplace – the hazards
We see gas cylinders in use across the wide range of clients we visit. Some will use cylinders to power their MHE (Materials Handling Equipment) and some will be using gases to complete welding and cutting operations as part of their production process.
Moving gas cylinders To lift or not to lift; that is the question
The key issue with cylinders and their movement relates to handling and lifting. Many workplaces are equipped with various handling equipment and it’s tempting to use one of a number of means to lift cylinders. It’s also quite tempting to manually handle cylinders into position when the distances aren’t too great.
The risks of moving gas cylinders
We’ve seen in real life a number of situations where a high risk method has been used to move cylinders, check through the examples below and see if you recognise any of these from your past experience of perhaps even your own site;
Manual handling by churning (rolling on the base);
This is a valid method but what about tall and heavy cylinders and moving them through a cluttered and busy workplace? One drop can cause significant damage to the cylinder, or even the valve, creating a ballistic missile capable of passing through walls! The is suitable for short movements of easily handled cylinders only (<5m).
Lifting using fork lift truck attachments;
This is fine if the cylinders are safely stored on a pallet or cradle but using attachments such as barrel clamps, scissor clamps or magnets – this can damage the cylinder walls with catastrophic consequences.
Lifting using the valve shroud or valve itself;
Lifting on the valve shroud can cause it to detach from the cylinder, it’s just not designed for a suspension lift.
Lifting on the valve it certainly a very bad idea – again, it’s not designed for this and could lead to leaks, sudden failure and may of course slip from the lifting sling – this is the highest risk and must always be avoided.
What should you do?
In simple terms follow the guidance issued by the BCGA, which you can download here; BCGA TIS 28
If you still have questions perhaps now is a good time to ask an experienced consultant from Outsource Safety to review your current procedures. We can visit and carry out specific risk assessments or even a comprehensive Gap Analysis in line with the requirements of the internationally recognised Management Standard OHSAS18001, contact us for more information.
You might be wondering why this post is here, if you are you’re probably not aware of the wide range of clients which we work with!
This post relates to the commercial rather than residential use of these spa’s but if you’re lucky enough to have one at home there are some good points below which are worth being aware of linked to HSE document HSG282 “Control of legionella and other infectious agents in spa-pool systems” published in January 2017.
The simple facts are that these warm agitated pools of water provide a good breeding ground for a number of harmful bacteria; folliculitis, e-coli, viral skin infections and of course legionella. Add to this the risk of droplet inhalation through agitation and the risk increases significantly.
The key risk is that water in these pools is kept at a steady 30-40oC, an ideal temperature for these bacteria to breed in, but don’t forget the other key associated risks such as;
If you’re a user of such equipment ask your hotel or operator if water is changed between rental groups as required by this guidance and check that a robust in line disinfectant feeder has been installed as you cannot rely on direct chemical dosing through tablets.
This is an interesting question which sometimes arises for the hundreds of clients we support across the UK. Imagine that a new employee starts working at your business or a temporary employee becomes permanent and they already have their own Personal Protective Equipment (PPE).
Given the links back to the Health and Safety At Work Act and its requirement not to charge employees for protective equipment some staff can become confused on whether this is actually permitted. Looking in more detail at the specific regulations covering PPE leads us to Regulation 4 of the Personal Protective Equipment at Work Regulations 1992 which states that employers have a duty to “ensure that suitable PPE is provided” to employees who need it.
Can staff bring their own PPE to work?
Looking at the above you can see that if you haven’t provided PPE that isn’t the issue but you do have to ensure that it’s correct for the job. The key issue here relates to suitability and here are a few instances which you may like to check;
Safety boots provide the right slip resistance and protection – mid sole protection for example;
Respiratory protection is adequate and will give protection from the dusts or vapours encountered (FFP rating);
Eye protection is adequate (impact rating or chemical protective);
Hard hats are within your requirements for manufacture date (typically 3-5 years from manufacture depending on your policy.
One final thing to remember is that fake PPE is surprisingly common, particularly when individuals buy PPE from the internet at a reduced cost, and individuals are likely to be more cost sensitive.
The final choice is yours, if you’re in a higher risk industry you may wish to start afresh with issuing equipment which you know to be right for the job. If on the other hand if you’re an occasional user of PPE you may well not need to go to the expense of issuing new equipment if an employee can bring suitable items themselves.
Don’t forget, once they do work for you you will need to pay for the supply of their PPE.
Contact us on 01453 800 100 if you need expert help with health and safety for a fixed cost.
Control of the Lifting Operations: The code recommends the appointment of a responsible person as Appointed Person to plan and control the lifting operations.
Note: we provide expert health and safety support packages and competent person support for construction. However, we do not provide a lift planning service, please contact your lift provider. We also help hundreds of clients each year with their SSIP applications (SMAS, CHAS, Constructionline and similar)
The duties of the Appointed person can be summarised as follows:
Familiarity with the relevant legislation and any project Health and Safety Plan
Assess the operation to enable planning, selection of the crane and lifting equipment, and the instruction and supervision for the operation to be undertaken safely
Ensuring that adequate inspection, maintenance and testing of the equipment has been carried out
Taking responsibility for the organisation and control of the lifting operation
The code also designates three categories of lift – each has a slightly different requirement in terms of the safe system of work.
basic lift
standard lift
complex lift
Crane Hire versus Contract Lifting
BS7121 makes a clear distinction between Crane Hire, where the Hirer has responsibility for the planning and organisation of the lifting operations and Contract Lifting where the main responsibilities of planning, organising and supervising the lifting operation are contracted out to the Crane Owner.
A summary of the respective responsibilities are:
Crane Hire: The Hirer must:
Plan the lift and operate a safe system of work
Supply the Appointed Person
Carry out all work in accordance with BS7121
Ensure all equipment used is tested and certified and free from any visible defects
Contract Lift: The Crane Operator must:
Plan the lift and operate a safe system of work
Supply the Appointed Person
Carry out all work in accordance with BS7121
Ensure all equipment used is tested and certified and free from visible defect
Of importance but outside the scope of BS7121 are the different insurance arrangements within Crane Hire and Contract Lifting. Under Crane Hire, the Hirer must ensure the operator and crane under third-party liability and hired in plant policies. With certain exclusions, these are covered under Contract Lift terms.
Planning the Lifting Operation
All lifting operations must be carefully planned so that foreseeable risks have been accounted for and relevant controls put into place.
Planning of the lift should include:
General
Taking into account the load, its characteristics and the method of lifting
The selection of a suitable crane
The selection of suitable lifting equipment
The position of the load before, during and after the lifting operation
The site, including space available and proximity hazards
Welding fumes from mild steels, zintec (zinc alloys), stainless steels, brass, aluminium and phospor bronze all carry a significant risk of long term health problems if exposure is not properly controlled. As occupational hygienists and qualified safety consultants we have many years experience of carrying out air sampling surveys to determine occupational exposure to welding fumes and similar substances.
Air sampling – Welding of Galvanized (zinc coated) Products
Welding of galvanized steel is completed in a very similar way to welding of the bare steel of the same composition. The same welding processes, volts, amps, travel speed, etc. can be used with little modification when the switch is made from uncoated steel to galvanized steel, unless the zinc coating is unusually thick.The difference between welding galvanized steel and welding uncoated steel is a result of the low vaporization temperature of the zinc coating. Zinc melts at about 480°C and vaporises at about 900°C. Since steel melts at approximately 1,500 °C and the welding arc temperature is 8,300 to 11,000°C, the zinc that is near the weld is vaporised. By the time the weld pool freezes, the zinc is gone giving rise to two immediate consequences:
The vaporized zinc increases the volume of welding smoke and fumes.
The zinc at and near any welds is actually burned off by the heat of the arc, removing the protective zinc coating.
Sometimes a white dust can be seen following welds and this is typically zinc oxide, inhalation should be avoided.
Welding fumes sampling method
A measured volume of air is drawn through a membrane filter mounted in a sampler, and the mass of fume collected is determined by weighing the filter before and after sampling subject to a period of stabilisation. The difference in weight reflects the mass of the fume collected and this, coupled with the flowrate and time period, enable the fume levels to be quoted as milligrams per cubic metre (mg.m-3).
Use of welding fume data for the assessment of exposure
Compliance with Regulation 6 of the COSHH Regulations will be ensured if the occupational exposure standard for particulate welding fume does not exceed 5 mg.m3, provided exposure to other toxic constituents of the fume which have lower occupational exposure limits are adequately controlled. It follows that where the fume contains one or more toxic constituents which have lower occupational exposure limits the OES of 5 mg.m3 may no longer apply.In these circumstances the exposure to individual constituents of the welding fume may have to be quantified separately. This procedure may be simplified for purposes of assessment and, where appropriate, monitoring under the COSHH Regulations. The total weight, in mg.m3, of welding fume at which each of the components of the fume will reach its occupational exposure limit can be calculated from the consumable suppliers’ fume analysis data.
Welding Fumes- Background Information
Welding fume is a varying mixture of airborne gases and fine particles which if inhaled or swallowed may be a health risk. The degree of risk will depend on:
the composition of the fume;
the concentration of the fume; and
the duration of exposure.
The main health effects are:
(a) IRRITATION OF THE RESPIRATORY TRACT
Gases or fine particles of fume can cause dryness of the throat, tickling, coughing, tightness of the chest and difficulty in breathing.
(b) METAL FUME FEVER
Inhaling many freshly formed metallic oxides, such as those of zinc, cadmium, copper etc., may lead to acute flu-like illness termed metal fume fever. With the exception of exposure to cadmium fume serious complications are rare. The most common cause of metal fume fever is welding galvanised steel.
(c) SYSTEMIC POISONING
Systemic poisoning can result from inhaling or swallowing substances contained in welding fumes such as fluorides, hexavalent chromium, lead, barium and cadmium. The presence of these substances in the fume depends upon the welding process being used and the material being welded.
(d) LONG TERM OR CHRONIC EFFECTS
Inhaling welding fumes can lead to benign X-ray changes, referred to as siderosis. A subject of current concern is whether welders have an increased risk of developing respiratory cancer, as certain constituents of some welding fumes, such as hexavalent chromium and nickel, may be carcinogenic.
ORIGIN AND CONSTITUENTS OF FUME
To evaluate the risk to health from exposure, information is required on the sources of welding fume and gases. Usually more than 90% of particulate welding fume arises from the vaporisation of the consumable electrode or rod. The metal being welded usually dictates the welding process and the consumable used, but it does not itself contribute significantly to the particulate fume composition except at certain operations which include:
(a) welding through metallic coatings, e.g. zinc and cadmium plated materials;
(b) welding through painted surfaces such as those which contain lead compounds;
(c) removal of base metal, e.g. cutting or arc gouging.
Depending on the welding process, gases encountered during welding may be:
(a) fuel gases which are used in gas welding and cutting which on combustion will produce carbon dioxide and in some circumstances carbon monoxide;
(b) shielding gases such as argon, helium, carbon dioxide or mixtures of these gases. These gases may be toxic or asphyxiant;
(c) gases produced by the action of heat upon the welding flux or slag, such as carbon dioxide and monoxide;
(d) gases produced by the action of heat or ultraviolet radiation upon the atmosphere surrounding the welding arc. These may include nitric oxide, nitrogen dioxide, and ozone. Ozone may be formed at some distance from the arc, depending upon the welding process being used and the metal being welded.
FACTORS THAT INFLUENCE THE COMPOSITION AND CONCENTRATION OF FUMES AND GASES
The quantity and composition of welding fume and gases are influenced by a number of variables, usually dictated by the job requirements. The most important variable is the type of process: however, it does not necessarily follow that exposure to welding fume will be the same for all welders using a similar process. Therefore each welder should be assessed individually in relation to the job that is being carried out. To ensure an adequate assessment of exposure is made it is necessary to consider each of the factors which are relevant to the particular welding operation..
Gas shielded welding
Gas shielded welding uses a continuous solid wire consumable to provide filler metal and form the arc which is protected by an inert gas shield such as argon or helium (MIG (metal inert gas) welding), or an active gas shield such as carbon dioxide or mixtures of gases containing carbon dioxide or oxygen and an inert gas (MAG (metal active gas) welding). Process variables are important: the arc length increases with the current and the mode of metal transfer changes from globular to spray, with a consequent increase in emission of particles and pollutant gases. Another mode of transfer is obtained by using pulsed current conditions, the fume emission rate will depend upon the welding parameters.
Note: when welding aluminium a change to 98% argon gas can help to create cleaner welds and also reduces the generation of Ozone significantly (a respiratory irritant).
THE EFFECT OF WELDING CONSUMABLE ON CONCENTRATION AND COMPOSITION
The type of consumable used, and its chemical composition, will be dictated by the technical demands of the welding process. Various types are available. MIG consumables may consist of a solid bare wire, or copper coated wire and, in the case of FCW, a tubular wire containing flux in-fill. The type of consumable will affect not only the quantity of particulate fume produced, but also its composition.
An adequate assessment of the risk to health from exposure to welding fume needs information on the chemical constituents and their concentration in the fume. Welding fume will usually contain all the chemical elements present in the consumable, although the proportion and toxic nature will have changed as a result of physical and chemical processes which occur during welding. The most important changes concern consumables that contain chromium, such as those used in hardfacing and welding of stainless steel. Chromium metal in arc welding processes oxidises to trivalent chromium compounds but also some conversion to hexavalent chromium may occur. This is important because trivalent and hexavalent chromium have different occupational exposure limits. Trivalent chromium compounds have an OES of 0.5 mg.m3 whereas the ‘guidance value’ given in Table 4 of Guidance Note EH 40 for hexavalent chromium is ten times lower at 0.05 mg.m3. Where hexavalent chromium is present in welding fume it will therefore be the principal substance of hygiene interest.
Stainless steel MIG welding fume usually contains up to 18% chromium but only a small percentage is likely to be present as hexavalent chromium. An adequate assessment of health risk requires information on the chemical constituents and their concentrations produced from a given consumable during a specified process.
The Welding Manufacturers Association has produced a standard format for hazard data sheets for welding consumables to enable their members to comply with their legal obligations under the Health and Safety at Work etc. Act 1974 Section 6. Most UK manufacturers and suppliers now provide information using this format. The hazard data sheets should include information on chemical analysis of substances of hygiene interest present in the fume produced by the consumable, the appropriate OELs, and an indication of the measures necessary to ensure adequate control.
THE EFFECT OF SURFACE TREATMENT AND PARENT METAL ON COMPOSITION
The composition of the welding consumable is of primary importance in assessment of exposure of welders to fume. In certain circumstances, however, and at specific types of welding operation the surface treatment and composition of the parent metal also need to be considered. Fume from oxygen arc cutting, and flame gouging processes and flame cutting will consist of particulates which are generally similar in composition to the parent metal. Information on the composition of the metal or alloy is important to establish the fume composition and the relevant OEL which will apply. It is likely, although no information is available, that chromium in fume from arc gouging of alloy steels will be present in the hexavalent form and the guidance value of 0.05 mg.m3 for hexavalent chromium will apply.
Surface treatment may include zinc galvanising, cadmium plating or applications of paint primers and sealers. When welding or cutting operations are carried out on coated steels additional constituents of the fume will be formed by the effect of heat on the surface coating. These may include oxides of the metal used for coating, or thermal degradation products from the primer application. Suppliers of coated steels and primer formulations have duties under HSW Act Section 6 to provide information on the composition of the material , the risks and precautions which should be taken during welding. Similarly welding directly on to steel which is coated with oil, to prevent corrosion, can give rise to smoke containing polycyclic aromatic hydrocarbons.
Welding or flame cutting existing steel structures or cutting metal scrap presents particular problems, as the composition of the metal alloy and any surface coating will not be known. Old structures and plant are frequently coated with paint that may contain lead, zinc, chromate or cadmium pigments, which will increase both the quantity and toxicity of the fume emission. Surfaces treated with PVC and/or chlorinated rubber coatings decompose with heat to give fume and gases containing hydrochloric acid and phosgene. In all cases of cutting and welding it is necessary as part of the assessment to determine the composition of any surface treatment, and the metal where appropriate, before work starts, to prevent or control exposure to toxic substances.
Welding certain metals can produce high concentrations of ozone. The predominant pollutant during MIG/MAG welding of aluminium and aluminium alloys is ozone, similarly significant concentrations of ozone are produced during TIG and MIG welding of stainless steel. Ozone is formed by the effect of ultraviolet radiation from the arc on atmospheric oxygen and can be produced some distance from the arc. Effective control of particulate fume emission in certain circumstances can result in significant increase of ozone generation. This is because particulate welding fume may reduce or inhibit emission of UV radiation from the arc.
JOB ASPECTS THAT AFFECT EXPOSURE TO WELDING FUMES
The type of process, size and composition of any consumable used will influence the amount of fume generated and its composition. However, the extent of exposure to welding fume is considerably influenced by the skill of the welder. Changes in current, voltage, welding angle and arc gap can significantly increase or decrease the quantity of fume generated in a given time.
Welding position
The principal welding positions are flat (downhand) horizontal, vertical and overhead. The downhand position is most commonly used and also induces the highest fume levels in the welder’s breathing zone. The welder’s posture in relation to the welding position is also important: exposures of welders in a crouching position are significantly higher than exposures of welders working in a sitting position, and exposure to fume when standing is intermediate between the crouching and sitting position. These differences reflect the proximity of the welder to the welding plume, and every effort should be made to prevent head and shoulder contact with the plume, by changes where practicable to the working position.
Welding location
Equally important is the location of the welding process. In a large workshop and welding on an open structure welding fume and gases will be partially dispersed and diluted by air movement, and although exposure of the welder may be high during arcing the fume and gases do not accumulate in the working area. In a small workroom, or in a space with restricted air movement, fume from welding processes will not disperse so readily, with the resultant increase in average exposure. Work in confined spaces, such as internal welding of process plant or in ship construction, can lead to accumulation of high concentrations of particulate fume, by-product and shield gases, which do not disperse and require the use of efficient ventilation systems to ensure that exposure is adequately controlled and there is no depletion of oxygen of the working atmosphere.
Duration of exposure
Both long term and short term limits relate to the concentration averaged over a specific reference period. For most substances contained in particulate welding fume the averaging period for the occupational exposure limit is eight hours. Exposure to welding fume will be intermittent, the highest exposures occurring during the welding operation, i.e. during arcing or flame cutting. The periods between the actual welding operation should give rise to minimal exposure to fume, although this will depend upon the size of the workshop, the number of welders, their work patterns and effectiveness of control measures and general ventilation. The pattern of work, the arcing time and down time for any individual welder will vary from day to day and similarly duration of exposure and pattern of work will vary significantly between welders although they may be doing similar work. Exposure (to substances hazardous to health) should be calculated according to the approved method, which is reproduced in Appendix 1 of Guidance Note EH 40. Assessment of average exposure becomes very difficult and will require frequent sampling unless the welding operation is of a routine nature, for example production line welding of domestic boilers.
Exposure to solvents such as toluene, xylene or similar substances carries a risk of long term health problems if exposure is not properly controlled. As occupational hygienists and qualified safety consultants we have many years experience of carrying out air sampling surveys to determine occupational exposure to many types of solvent used in paints, glues and mastics amongst other substances.
If you would like to speak to one of our safety consultants or occupational hygienists about an air sampling survey for wood dusts please contact us on 01453 800100. Outsource Safety specialise in Occupational Health and Hygiene consultancy.
Xylene and toluene sampling methods
An activated charcoal badge type dosimeter was used, attached at the lapel. The badge was left exposed for a recorded period and later washed through with a solvent to extract the analyte which is then passed through a gas chromatography instrument to analyse the concentration of particular substances, in this case xylene and toluene were selected.
Xylene – Background Information
OCCUPATIONAL EXPOSURE STANDARDS
8-HOUR TWA: 100 ppm
15-MINUTE REF. PERIOD: 150 ppm
IDENTITY AND PROPERTIES
CAS No: 1330-20-7
EEC No: 601-022-00-9
Formula: C6H4(CH3)2
Synonyms: xylol, dimethylbenzene
Saturated vapour
concentration: about 8000 ppm at 20oC
Boiling point: 137-144 oC
Conversion factor: 1 ppm = 4.34 mg.m-3 at 25oC
Xylene is an aromatic hydrocarbon with a characteristic odour, perceptible at about 1 ppm. Commercial xylene is a mixture of the three xylene isomers and may contain some ethyl benzene. It is a clear, colourless, mobile, fairly volatile fluid, which is insoluble in water and miscible in other organic solvents. Xylene is classified under the CHIP 2 Regulations (1994) as harmful, to be labelled with risk (R) phrases:
R10: FLAMMABLE
R20/21: HARMFUL BY INHALATION AND IN CONTACT WITH SKIN
R38: IRRITATING TO SKIN
OCCURRENCE AND USE
Xylene is produced mainly from crude oil in the UK, but some also arises from coking processes. It is a component of petrol and hydrocarbon solvent mixtures; and is used in chemical manufacture and as a solvent. Individual isomers are raw materials for making terephthalic acid and phthalic anhydride. It is a carrier solvent for surface coatings (e.g. paints, adhesives, pesticides) supplied for commercial and domestic use.
EXPOSURE
Many thousands of workers may be potentially exposed to xylene, with more than 10 000 user-firms in the UK. Typically, exposures to xylene vapours are controlled to below 50 ppm where xylene is used as a chemical precursor and in the manufacture and use of formulated products. Higher exposures may occur in spray-painting large items, printing, and using xylene-containing products in confined spaces; in these circumstances respiratory protective equipment is worn. Short-term exposures up to 500 ppm have been reported in machine-cleaning operations.
MEASUREMENT
Long-term monitoring is performed by pumped sampling with solvent desorption or by diffusive sampling and thermal desorption {Methods for the determination of hazardous substances MDHS 66 (Rev) MIXED HYDROCARBONS (C5 TO C10) IN AIR – LABORATORY METHOD USING POROUS POLYMER DIFFUSION SAMPLERS, THERMAL DESORPTION AND GAS CHROMATOGRAPHY ISBN 0 7176 0867 0 HSE Books (1995)} and gas chromatographic determination. Measurement of the urinary metabolite methyl hippuric acid is a suitable biological indicator of uptake.
METABOLISM
Xylene vapour is rapidly absorbed through the respiratory tract. It is also absorbed by skin contact, and penetrates many materials used for protective clothing. Over 90% of the absorbed dose is metabolised and excreted in the urine as methyl hippuric acid. A small proportion (5%) is exhaled in the breath.
HEALTH EFFECTS
Animal studies
Exposure to high concentrations of xylene has been shown to cause hearing loss and enlargement of kidneys and liver, due to high metabolic demand. Toxicity to reproduction has been observed, but only at or near levels which are maternally toxic. Xylene gave negative results in carcinogenicity and various mutagenicity tests.
Human data
Minimal eye, nose and throat irritation has been reported at levels down to 100 ppm for 30 minutes, and this can also arise with brief exposures at slightly higher levels. The principal effects known in humans are on the central nervous system. Exposure at 300 ppm affected the sense of balance, caused visual disturbances and slowed reaction-times and some effects were seen at 200 ppm; but exposure to 160 ppm over 4 hours caused no significant adverse health effects. At around 700 ppm for up to 1 hour, headache, dizziness and nausea occur. The isomeric composition of xylene is not considered an important factor in its health effects.
BASIS FOR SETTING THE LIMIT
The critical health effects are irritation and central nervous system effects. The irritant effects reported at 100 ppm appear to be minimal and this was considered to be a no-effect level. In view of these irritancy effects an occupational exposure standard was set at 100 ppm (8-hour TWA). Since irritant effects can arise with even brief exposures at higher levels a short-term OES was set at 150 ppm (15-minute reference period). The limits apply to o-, m- or p- isomers of xylene, or mixtures thereof. A ‘Skin’ notation was considered appropriate to indicate the potential for absorption by this route.
Toluene – Background Information
OCCUPATIONAL EXPOSURE STANDARDS
8-HOUR TWA: 50 ppm
15-MINUTE REF. PERIOD: 150 ppm
NOTATION: SKIN
IDENTITY AND PROPERTIES
CAS No: 108-88-3
EEC No: 601-021-00-3
Formula: C6H5CH3
Synonyms: toluol, methyl benzene
Saturated vapour
concentration: about 30 000 ppm at 25oC
Boiling point: 110.6oC
Conversion factor: 1 ppm = 3.75 mg.m-3 at 25oC
Toluene is an aromatic hydrocarbon with the typical sweet/pungent odour of such substances and an odour threshold around 3 ppm. It is a clear, colourless, mobile, volatile liquid which is insoluble in water and miscible with most organic solvents. Toluene is classified under the CHIP 2 Regulations (1994) as highly flammable and harmful, to be labelled with risk (R) phrases:
R11: HIGHLY FLAMMABLE
R20: HARMFUL BY INHALATION
OCCURRENCE AND USE
Toluene occurs naturally in crude oils and is now produced by catalytic reforming of petroleum feedstocks. About 150 000 tonnes per annum are used in the UK. Toluene has widespread use in the production of a range of industrial chemicals, and as a solvent in adhesives, including rubber solutions, coatings and printing inks. It is a common component of many mixed petroleum hydrocarbon solvents.
EXPOSURE
A large number of workers are potentially exposed to toluene. Processes at which exposure to toluene is well-controlled are in the petrochemical sector; exposures are fairly well controlled in the footwear industry (adhesives), silk-screen printing, chemicals production, paint manufacture and decorating industries. In each case mean exposures are less than 15 ppm with more than 96 % of samples less than 100 ppm. Poorly controlled processes include rubber-coating, machine-cleaning, and general adhesives uses, where mean exposures range from 15 to 89 ppm with only around two thirds of samples less than 100 ppm. High short-term exposures can be experienced at liquid transfer points and during manual cleaning. There is a potential for domestic exposure from paint and adhesives.
MEASUREMENT
Short-term measurement can be performed by colorimetric detector tubes, and continuous monitoring is with meters, but these may not be selective for toluene. Long-term measurement is by pumped sampling onto charcoal with solvent desorption, {Methods for the determination of hazardous substances MDHS 36 (Rev) TOLUENE IN AIR – LABORATORY METHOD USING PUMPED CHARCOAL ADSORPTION TUBES, SOLVENT DESORPTION AND GAS CHROMATOGRAPHY ISBN 0 11 885960 9 HSE Books (1990)} or diffusive sampling with thermal or solvent desorption, {Methods for the determination of hazardous substances MDHS 40 (Rev) TOLUENE IN AIR – LABORATORY METHOD USING PUMPED POROUS POLYMER ADSORBENT TUBES, THERMAL DESORPTION AND GAS CHROMATOGRAPHY ISBN 0 11 885961 7 HSE Books (1990)} and gas chromatographic determination. Biological assessment of toluene exposure is by measuring blood-toluene at the shift-end.
METABOLISM
Toluene is readily absorbed by the respiratory tract, and is also absorbed through the skin. It is rapidly distributed, accumulating to some extent in fat and also the liver, brain and lung. Some toluene is exhaled: otherwise it is metabolised to hippuric acid and o-cresol, which are excreted in urine over an extended period.
HEALTH EFFECTS
Animal studies
Inhalation studies showed narcosis at 10 000 ppm, following central nervous system effects. In repeated studies at high exposures, kidney and liver damage occurred, with no effects at 200 ppm. It is difficult to form firm conclusions on findings that exposure to toluene may cause hearing or eyesight impairment.
IN VIVO and IN VITRO studies show toluene is unlikely to be carcinogenic or mutagenic. Toluene only showed teratogenic effects at high doses.
Human data
The principal effects are on the central nervous system with impaired reaction times and vigilance reported for exposures to 200 or 240 ppm for 3 to 7 hours, and dizziness, headache and fatigue reported following exposure at 50 to 100 ppm for 4 to 8 hours. Although longer term effects on the central nervous system have been claimed, there is no substantive evidence that they occur following repeated exposures between 50 and 200 ppm. Toluene vapour is irritating to the eyes and respiratory tract, with no effects being reported at 80 ppm. The liquid irritates the skin. There are no data on carcinogenic effects in humans.
BASIS FOR SETTING THE LIMIT
The critical health effect is upon the central nervous system. A level could be identified which was unlikely to be injurious to employees, and an occupational exposure standard was set at 50 ppm (8-hour TWA) on this basis. However, this implies a need to introduce improvements in control in some industry sectors. A short-term OES was set at 150 ppm (15-minute reference period) which would minimise short-term effects such as irritation. A ‘Skin’ notation was considered appropriate.
This is a question which has been raised by some clients following a spate of emails circulating on the web. Read on to find out the opinion of our experienced safety consultants and if you have questions or need more advice please call our safety consultancy on 01453 800100.
Below is a copy of the email (in italics) which started this urban myth;
Email Subject: Drinking Bottled Water Kept in Car
…a friend whose mother recently got diagnosed with breast cancer. The doctor told her women should not drink bottled water that has been left in a car. The doctor said that the heat and the plastic of the bottle have certain chemicals that can lead to breast cancer. So please be careful and do not drink that water bottle that has been left in a car and pass this on to all the women in your life.
This information is the kind we need to know and be aware and just might save us!!!!
*The heats causes toxins from the plastic to leak into the water and they have found these toxins in breast tissue. Use a stainless steel canteen or a glass bottle when you can*!
The first alarm bell which rings here and announces this email as something which may not be 100% true is the fact that all materials containing food stuffs must pass stringent tests before being put into use.
However, there is as usual an element of truth, bottles can potentially leach endocrine disruptors into the water which they contain, in this case man made chemicals which have the potential to interfere with the production of reproductive hormones in the body – not cause cancer.
Research on this subject is in its early stages and there may not be a link – more research is needed but it is a potential concern. Some chemical leaching does take place but these are at levels which are minuscule and do not pose a threat to health. Tests have shown them to always be within the limits set within the EU and US authorities. You’re greatest risk is from microbial contamination, particular in the case of still mineral waters which will not have undergone special treatment to reduce these levels.
The bottom line is that single use water bottles are known to be safe and multiple use water bottles are also safe to the best of current knowledge. Nothing is without risk but you should not be concerned by leaving water bottles in cars but you might not want to drink the warm water anyway – unless you’re very thirsty!
Notes
Some concerns have also been raised involving reusable water bottles and the leaching of bisphenol A (BPA). You may now see a number of baby bottles boasting to be BPA free. This is potentially a concern but research continues into this to establish the actual level of risk and its true effects on the human body.
Electrical equipment should be visually checked regularly. Equipment should be more thoroughly tested by a competent person often enough that there is little chance that the equipment will become dangerous between tests. We can offer a one day training course to provide that competence in house giving you flexibility and cost savings. We often get clients asking for advice when its comes to electrical testing. From PAT testing (portable appliance tests) through to building supply inspections it seems that the waters are rather murky and many business people are frustrated by a lack of clear guidance on what they must do rather than what they could do. This is further complicated by a range of suppliers who all provide information in a way which makes you suspect that their intentions are more commercial than educational.
How often should I carry out PAT testing on my electrical equipment?
Portable appliances You should have a scheme of inspection (could be visual) by a person competent to spot the risk issues (not necessarily an electrical engineer). However, you’ll find that pretty much everyone interprets this as having a company carry out portable appliance tests (PAT Testing) once a year for portable equipment (less often for fixed equipment like photocopiers and more often for equipment in tough environments like workshops or construction).
It is your choice to do otherwise but we’d recommend the above, if you wish to do it in house companies such as ourselves can offer one day training courses to give sufficient competence to operate a tester and carry this task out.
Electrical installations Typically your insurer will ask to see evidence of inspection and test on a five yearly basis. If you have recently moved into your offices you should be in receipt of a handover certificate which states that the installation was carried out in line with the requirements of the current IEE Regulations (17th Edition) and all is well. Once you get five years beyond this its time to review and you’ll need to get hold of a competent contractor to do this for you (NICEIC for example).
Remember, there can be a lot of power moving through the system hidden behind walls and in risers cupboards, poor connections can be overheating or perhaps sparking leading to fire and major problems. Perhaps have a shop around, a larger contractor with heat sensing camera equipment might actually work out to be better value than having to shut down sections whilst the survey is completed.
In summary, none of this is strict law but it is alluded to in the regulations as being reasonable. The fact that just about everyone else is doing it makes complying your best option in this case. If you have questions then please contact one of our health & safety consultants by calling us on 01453 800100.
More information on PAT test frequency (for guidance only, make your own assessment through a competent person)
We have completed this guidance in response to the recent spate of emails which have raised serious concerns about the levels of benzene which can building up within cars and other vehicles left in hot weather. In common with most of these types of emails there is an element of truth to this statement but what is the true story? Read on to find out.
Starting with the basics, it’s true that benzene is a toxic chemical known to produce a variety of ill health effects, including anaemia and cancer (specifically leukaemia) in humans. Benzene occurs naturally (typically as a component of crude oil) and you’ll also find it used in a range of products as a solvent (plastics, synthetic fibres, dyes, glues, detergents and drugs). It’s also a constituent of tobacco smoke and it present in petrol and petrol exhaust fumes.
Low levels of benzene are often present in outdoor air due to vehicles exhausts and industrial emissions. Vapours containing measurable levels of benzene are emitted by household products such as glues, paints, and furniture wax as products ‘gas off’. Due to this effect even higher levels of benzene can sometimes be found indoors, especially in new buildings with new fixtures and fittings.
Benzene in cars
Given the evidence above we have to conclude that dashboards, door panels, seats, and other interior components do emit benzene, as claimed in the email. In most cars these items will be made from plastics, synthetic fabrics and glues, some of which will have been manufactured using benzene may therefore “off-gas” trace amounts of benzene, particularly under hot conditions.
Scientific research
Most published studies where benzene levels have been measured inside vehicles have been done under typical driving conditions, i.e. in traffic. While such studies have found that benzene levels can significantly exceed those outside the vehicle and could pose a human health hazard, this is mainly attributed to the presence of exhaust fumes from other traffic.
Also, the amounts of benzene actually detected by researchers were significant but were far lower than the amounts that have been stated in these emails. A 2006 study reported in-vehicle benzene levels from exhaust fumes ranging from .013 mg to .56 mg per cubic meter — a far cry from the 400 mg to 4,000 mg reported.
Benzene levels in parked cars
In the one study found that took measurements of benzene levels inside parked cars with their engines turned off, the results were more benign. Toxicologists took samples of the air inside both a new and a used vehicle, under simulated hot-sunlight conditions, measuring the levels of volatile organic compounds (VOCs) including C3- and C4-alkylbenzenes, and exposing human and animal cells to the samples to determine their toxicity. Despite the detectable presence of VOCs (a total of 10.9 mg per cubic meter in the new car and 1.2 mg per cubic meter in the old car), no toxic effects were observed. Apart from noting the slight possibility that allergy-prone individuals might find their condition exacerbated by exposure to such compounds, the study concluded there is “no apparent health hazard of parked motor vehicle indoor air.”
When in doubt, ventilate
Despite this finding, some drivers may still be concerned about the presence of any benzene vapours inside their car, especially given the World Health Organization’s stated position that there is “no safe level of exposure” to the carcinogen. They may also worry that turning on the vehicle’s air conditioner might exacerbate their exposure to trapped toxins by recirculating contaminated air. If that’s the case, there’s no harm done — and much peace of mind to be gained — by simply opening the windows and ventilating the car before turning it on.
We often have questions regarding which mask should be used and so thought a very quick summary here would be useful.
In general, filtering face masks used for dusts and similar can be categorised into three types all with an FFP number.
FFP1 for simple dusts such as nuisance and soft wood dusts
FFP2 for more hazardous dusts such as grinding, powder painting or respirable cystalline silica
FFP3 for hazardous dusts which also involve some vapours and gases which are hazardous to health (a good example here would be welding fumes)
One of the key failing when we review the use of face masks is how people wear them and you should, since November 2002 in fact, be testing the fit of these items to ensure they are effective – this is known as fit testing.
Many people do not fit masks well and do not even press the metal strip fixed around the nose of the mask to get a good seal – if a mask is to protect you this is essential. A second common error is keeping the mask at the point of work uncovered – perhaps on a work bench. This will allow the mask to collect exactly what it should be protecting you from and allow you to inhale it as soon as you use it! Always keep RPE in a sealed container or bag to prevent this type of contamination.
More information is supplied below on the new APF figures. These allow you, once occupational hygienists, such as ourselves, have completed an appropriate air sampling survey, to select an item of RPE which will adequately protect you and your staff from harm (see graphic to the right for more information). The APF is an allowance over which the mask will protect you;
For example; the allowable limit for hard and soft wood dusts is currently 5 mg per cubic metre. In your workplace an occupational hygienist such as one of our safety consultants may measure the dust level at 3 times this amount, 15 mg per m3. In that case you would need to seek an APF (assigned protection factor) of at least 3. This would put you in the typical 4-10 or 4-20 range.
One final point concerns the amount of time which a mask will last before requiring replacement, this can be summarised as follows;
For particulate (dusts) when breathing become more difficult the mask will be partially blocked and should be replaced
For gases and vapours the mask should be replaced when you detect ‘breakthrough’ i.e. when you can detect through smell or taste the item against which you should be protected be that a solvent or other substance.
As a general rule, disposable masks should be disposed of daily and reusable half face respirators should have their filters changed at least monthly.
If you would like to speak to an experienced occupational hygienist about this please contact us on 01453 800100
This is an interesting question which sometimes arises for the hundreds of clients we support across the UK. Imagine that a new employee starts working at your business or a temporary employee becomes permanent and they already have their own Personal Protective Equipment (PPE).
Welding fumes from mild steels, zintec (zinc alloys), stainless steels, brass, aluminium and phospor bronze all carry a significant risk of long term health problems if exposure is not properly controlled. As occupational hygienists and qualified safety consultants we have many years experience of carrying out air sampling surveys to determine occupational exposure to welding fumes and similar substances.
