| Concrete Products Health Risks
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It is not only for what we do that we are held responsible, but also for what we do not do.
Molière (Jean-Baptiste Poquelin) 1622-1673.
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There are so many benefits to the use of concrete products that their demand as
construction materials is assured for some time. However, as with other popular
industrial components such as asbestos, uranium, mercury and lead,
there are hidden and perhaps insidous risks. Fortunately, proper debris management
carefully integrated with production processes can reduce disease and fatalities
almost completely.
Concrete, masonry and many rock based materials including sand and gravel contain
respirable crystalline silica. It is in the fine grey powder that hangs in the air
and coats everything in a concrete construction site. It is microscopic shards of
quartz and similar glass-like minerals that act to lacerate the lungs. The damage
occurs at the molecular level on the interface where oxygen is extracted from the
air and transferred into the blood to sustain activity of the body's cells. The
constant slicing of this membrane creates the formation of scar tissue that progressively
reduces the lungs’ ability to absorb oxygen. The process continues to develop after
exposure has stopped, even appearing years later, and is irreversible. See
Silica Death Risk by Occupation and Industry.
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The full effects of respirable silica are often delayed or disguised. Acute,
accelerated or chronic silicosis can result depending on the exposure duration
and concentration of silica absorbed. The dust can be retained in the lungs
for many years and the effects are worsened by smoking. It can
take from weeks to decades to develop and symptoms can begin
to appear years after exposure has stopped. Victims also apparently die of
other causes such as heart failure, cancers or lung disorders when it was the
silica exposure that weakened these organs initially.
Results of silica damage include:
- Runny eyes, excess mucous in nose and throat, coughing;
- Shortness of breath, difficulty breathing with or without exertion;
- Rapid, shallow breathing, increased heart rate;
- Diminished chest expansion, reduction of lung volume;
- Lower work capacity, tiredness; muscle soreness;
- Emphysema, pneumoconiosis;
- Silicosis;
- Lung cancer, lung lesions;
- Pulmonary tuberculosis infection;
- Right heart enlargement and/or failure, cardiac arrest;
- Kidney failure;
- Autoimmune disorders such as scleroderma, an immune system disorder manifested by thickening and
fibrosis of the skin, lungs and other internal organs.
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Silica laden debris accumulates progressively from the oldest portions of a building such as
foundations, parkaids, utility rooms, ground levels and stairways. The formation is
largely complete when the greatest sources of concrete dust have been completed -
forming, chipping, grinding, coring, drilling and initial floor wear. Consequently,
these areas should be cleaned out and sealed as soon as permissible with original lockups,
work areas and storage areas staged closer to current activity where possible.
Control debris in the following order:
Level 3. Large items that must be handled manually or by machine.
Level 2. Materials that can be manipulated by hand, shovel or a stiff floor broom.
Level 1. Debris too large to vacuum yet too small to remove individually by hand such as plumbing and wiring bits,
plastic bags or wood and metal framing chunks. Minimize silica release with a good quality natural,
medium bristle floor broom, or synthetic, soft bristle, flagged edging or floor brooms.
Level 0. Sand, dust, grit and powder should be removed with a strong industrial vacuum cleaner. Hoses can be
lengthened to extend reach and flexibility. Pressure washing is recommended prior to surface coatings.
Note that all of these procedures release silica into the air. Consequently, good
quality respirators must be worn at all times. Standard particle masks are not
generally adequate for prolonged exposure to the fine levels of dust involved and
should only used for temporary situations. Also, major removal should be conducted
after hours if possible and work areas in progress cordoned off until properly
ventilated. Although vacuuming generally assures the minimum circulation of silica,
pressure washing is preferred for final finishing when sufficient drainage exists.
Stiff-bristled tools, traditional corn brooms in particular, should never be used for
Levels 1 or 0 debris removal indoors.
Concrete and masonry debris should always be completely removed prior to window and
drywall installation. Windows trap dust in the work environment ensuring
workers are subjected to maximum exposure. Heaters and fans are used to cure drywall
mud and speed production. This process unleashes the most respirable silica possible and
then circulates it precisely where people are working most often. Relatedly, stairwells
are commonly sealed off and unventilated which retains the dust in these frequently
used areas also. Subsequent dust from patching, grinding, tiling or floor leveling
operations must be removed immediately as an integral part of the production process.
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The following measures should be implemented to reduce silica exposure in the
workplace to prevent disease and related deaths in construction and industrial workers: ¹
- Recognize operations where silica dust may be generated and plan ahead to eliminate or control the dust at the
source. Awareness and planning are keys to prevention of silicosis.
- Do not use silica sand or other substances containing more than 1% crystalline silica as abrasive blasting materials.
Substitute less hazardous materials.
- Use engineering controls and containment methods such as blastcleaning machines and cabinets, wet drilling, or wet
sawing of silica containing materials to control the hazard and protect adjacent workers from exposure.
- Routine maintenance of dust control systems to keep them in good working order.
- Conduct air monitoring to measure worker exposures and ensure that controls are providing adequate
protection for workers.
- Use of adequate respiratory protection when source controls cannot keep silica exposures below the PEL.
- Wear disposable or washable protective clothes at the worksite.
- Practice good personal hygiene to avoid unnecessary exposure and other worksite contaminants such as lead.
- Shower (if possible) and change into clean clothes before leaving the worksite to prevent contamination of cars,
homes, and other work areas.
- Provide periodic medical examinations for all workers who may be exposed to respirable crystalline silica. E.g.
regular lung capacity tests in addition to hearing tests.
- Post warning signs to mark the boundaries of contaminated work areas.
- Provide workers with training that includes information about health effects, work practices and protective equipment
for respirable crystalline silica. An excellent outline for safety meetings is contained in Tailgate Meetings
That Work - Cement and Concrete  published by eLCOSH, the Electronic Library of OH&S.
- Report all cases of silicosis to provincial health departments and the WCB.
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Adapted from Preventing Silicosis and Death in Construction Workers,
The National Institute for Occupational Safety and Health (NIOSH).
Disability and death from exposure to respirable crystaline silica are largely avoidable.
The key is development and implementation of a hazardous debris logistics
plan carefully integrated into the ongoing production process. This plan should be
initiated at the design stage and registered, approved and monitored
by the site Safety Officer as is done in other hazardous situations such as fall
protection. Structured assessments of current conditions are available with the
Safety Checklist for Cement and Concrete. Detailed instructions for effective general management are contained in
Guides for Cristalline Silica Control Programs in Construction.
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Construction Debris Management Guidelines and Tools
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In combination with the procedures outlined above, these tools provide the structure and processes for a complete construction debris management program that can be adapted to your specific situation.
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Complete Silica Measurement and Management Program Software. download  OSHA, US
Crystalline Silica Primer, Special Publication. US Bureau of Mines
Guides for Managing Crystalline Silica Control Programs In Construction. NIOSH.
Industry Standards for Concrete Cutting and Drilling. Foundations in Safety, AU
Concrete and Masonry Construction. Occupational Safety and Health Administration (OSHA), US
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Waste Management at the Construction Site. Joseph Laquatra, Cornell University
Residential Construction Waste Management at the Construction Site. US EPA Office of Solid Waste
Contractor’s Guide.
Contractor’s Checklist.
Cost Savings Estimation Form.
Tracking Form.
Reporting Form.
Complete Asbestos Measurement and Management Program Software. OSHA, US
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Always use caution with material data sheets. No two are ever created equal because
there is currently no detailed standardization for reporting in some regards. Consequently,
five sheets for an identical product can all vary greatly in breadth and depth of content
including handling instructions. Independent sources are often more thorough than producers.
MSDS Solutions.
MSDS Online.
MSDS Internet Resources.
MSDS Speciality Databases.
NIOSH Pocket Guide to Chemical Hazards.
Toxicology Tutor.
Toxline.
PubMed Central.
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Concrete Products MSDS and Research |
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Crystalline silica is a common substance that is the basic component of sand, quartz, and granite rock. Construction materials that contain crystalline silica include: many abrasives used for blasting, brick, refractory brick, concrete, concrete block, cement, mortar, granite, sandstone, quartzite, slate, gunite, rock and stone, sand, fill dirt, top soil, and asphalt containing rock or stone. These materials are often present during construction, demolition, and renovation projects. When workers or bystanders (construction supervisors, inspectors, observers, or others near construction or similar work sites not performing the work generating the dust) inhale crystalline silica, the lung tissue reacts by developing fibrotic nodules and scarring around the trapped silica particles. This fibrotic condition of the lung is called silicosis. If the nodules grow too large, breathing becomes difficult and death may result. Persons with silicosis are also at a high risk of developing active tuberculosis. Silica exposures may result in the development of any of three types of silicosis:
Chronic Silicosis: usually occurs after ten or more years of exposure to crystalline silica at relatively low concentrations.
Accelerated Silicosis: results from exposure to high concentrations of crystalline silica and develops five to ten years after the initial exposure.
Acute Silicosis: occurs where concentrations are the highest and can cause symptoms to develop within a few weeks or four to five years after the initial exposure.
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| Breathing in the very fine dust of crystalline silica can lead to the development of silicosis. This involves scarring ofthe lung tissue and can lead to breathing difficulties. Exposure to very high concentrations over a relatively short period of time can cause acute silicosis, resulting in rapidly progressive breathlessness and death within a few months of onset. Similarly, accelerated silicosis, which can progress to death within a decade, has been associated with high exposures to silica in sand blasting. More common is progressive silicosis, usually because of exposure over a longer period. This causes fibrosis (hardening or scarring) of the lung tissue with a consequent loss of lung function. Victims are likely to suffer severe shortness of breath and will find it difficult or impossible to walk even short distances or upstairs. The effect continues to develop after exposure has stopped and is irreversible. Sufferers usually become house- or bed-bound and often die prematurely due to heart failure. Silica may be linked to lung cancer. If this is the case it is most likely that it occurs as a progression of lung fibrosis. Precautions taken to control the risk of fibrosis will serve to control the risk of lung cancer.
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| Silica exposure remains a serious threat to nearly 2 million U.S. workers, including more than 100,000 workers in high risk jobs such as abrasive blasting, foundry work, stonecutting, rock drilling, quarry work and tunneling. The seriousness of the health hazards associated with silica exposure is demonstrated by the fatalities and disabling illnesses that continue to occur in sandblasters and rockdrillers. Crystalline silica has been classified as a human lung carcinogen. Additionally, breathing crystalline silica dust can cause silicosis, which in severe cases can be disabling, or even fatal. The respirable silica dust enters the lungs and causes the formation of scar tissue, thus reducing the lungs’ ability to take in oxygen. There is no cure for silicosis. Since silicosis affects lung function, it makes one more susceptible to lung infections like tuberculosis. In addition, smoking causes lung damage and adds to the damage caused by breathing silica dust.
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Cement Dust Hazard: Exposure to cement dust can irritate eyes, nose, throat and the upper respiratory system. Skin contact may result in moderate irritation to thickening/cracking of skin to severe skin damage from chemical burns. Silica exposure can lead to lung injuries including silicosis and lung cancer.
Wet Concrete Hazard: Exposure to wet concrete can result in skin irritation or even first-, second- or third-degree chemical burns. Compounds such as hexavalent chromium may also be harmful.
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When hardened product is subjected to mechanical forces which generate dust particles, exposure to respirable silica-containing dust is possible. Prolonged and repeated inhalation of respirable crystalline silica-containing dust in excess of appropriate exposure limits has caused silicosis, a lung disease. Not all individuals with silicosis will exhibit symptoms (signs) of the disease. However, silicosis can be progressive, and symptoms can appear at any time, even years after exposure has ceased. Symptoms of silicosis may include, but are not limited to, the following: shortness of breath; difficulty breathing with or without exertion; coughing; diminished work capacity; diminished chest expansion; reduction of lung volume; right heart enlargement and/or failure. Smoking may increase the risk of developing lung disorders, including emphysema and lung cancer. Persons with silicosis have an increased risk of pulmonary tuberculosis infection.
Respirable dust containing newly broken silica particles has been shown to be more hazardous to animals in laboratory tests than respirable dust containing older silica particles of similar size. Respirable silica particles which had aged for sixty days or more showed less lung injury in animals than equal exposures of respirable dust containing newly broken particles of silica. There are reports in the literature suggesting that excessive crystalline silica exposure may be associated with adverse health effects involving the kidney, scleroderma (thickening of the skin caused by swelling and thickening of fibrous tissue) and other autoimmune disorders. However, this evidence has been obtained primarily from case reports involving individuals working in high exposure situations or those who have already developed silicosis; and therefore, this evidence does not conclusively prove a causal relationship between silica or silicosis and these adverse health effects. Several studies of persons with silicosis also indicate an increased risk of developing lung cancer, a risk that increases with the duration of exposure. Many of these studies of silicotics do not account for lung cancer confounders, especially smoking.
Crushed Concrete is not listed as a carcinogen by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), or the Occupational Safety and Health Administration (OSHA). In October 1996, an IARC Working Group re-assessing crystalline silica, a component of this product, designated respirable crystalline silica as carcinogenic (Group 1). The NTP's Report on Carcinogens, 9th edition, lists respirable crystalline silica as a "known human carcinogen." In year 2000, the American Conference of Governmental Industrial Hygienists (ACGIH) listed respirable crystalline silica (quartz) as a suspected human carcinogen (A-2). These classifications are based on sufficient evidence of carcinogenicity in certain experimental animals and on selected epidemiological studies of workers exposed to crystalline silica.
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Acute:
Swallowed: Unlikely under normal conditions of use, but swallowing concrete dust may cause irritation of the mouth and throat and may result in abdominal discomfort.
Eye: Concrete dust is irritating and corrosive to the eyes causing watering and redness and may result in corneal inflammation and ulceration.
Skin: The dust, particularly in association with heat and sweat, may irritate the skin, resulting in itching and occasionally a red rash.
Inhaled: Concrete dust is irritating to the nose, throat and lungs, especially in people with upper respiratory tract or chest complaints such as asthma.
Chronic:
Inhaled: Repeated exposure to the dust may result in increased nasal and respiratory secretions and coughing. Repeated inhalation of dry concrete dust containing crystalline silica can cause scarring of the lung (silicosis), lung cancer, and chronic bronchitis, and may increase the risk of scleroderma (thickening of the connective tissue) and kidney disease.
Skin: Repeated skin contact with the dust can lead to skin irritation and dermatitis. Concrete dust may cause sensitisation in some people resulting in dermatitis.
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| Between 1992 and 1998, the National Institute for Occupational Safety and Health (NIOSH) made visits to construction projects where concrete was being mechanically disturbed in order to obtain data concerning respirable crystalline silica dust exposures. The construction activities studied included: abrasive blasting, concrete pavement sawing and drilling, and asphalt/concrete milling. The results of this work indicate the potential for respirable quartz concentrations involving disturbance of concrete to range up to 280 times the NIOSH Recommended Exposure Limit (REL) of 0.05 mg/m3 assuming exposure for an eight- to ten-hour workday.
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Acute Inhalation: Cutting, grinding, crushing, or drilling hardened concrete or concrete products may generate dust containing crystalline silica. Repeated exposures to very high levels of respirable crystalline silica (quartz, cristobalite, tridymite) for periods as short as six months have caused acute silicosis. Acute silicosis is a rapidly progressive, incurable lung disease that is typically fatal. Dusts may irritate the nose, throat, and respiratory tract by mechanical abrasion. Coughing, sneezing, and shortness of breath may occur.
Chronic effects: Chronic bronchitis may result from chronic exposure to dust generated from cutting, grinding, crushing, or drilling hardened concrete. Chronic exposure to respirable limestone dust in excess of the ACGIH TLV has caused pneumoconiosis (Dusty Lung). Concrete dust may contain more than 0.1% crystalline silica, which is a cancer hazard if inhaled. Cancer risk depends on duration and level of exposure. Prolonged exposure to crystalline silica can cause silicosis, a progressive pneumoconisis (lung disease).
Silicosis: The major concern is silicosis, caused by the inhalation and retention of respirable crystalline silica dust. Silicosis can exist in several forms: chronic (or ordinary), accelerated, or acute. Simple silicosis may be progressive and may develop into complicated silicosis or progressive massive fibrosis (PMF). Complicated silicosis or PMF is characterized by lung lesions (shown as radiographic opacities) greater than 1 centimeter in diameter. Advanced complicated silicosis or PMF may lead to death or heart disease secondary to the lung disease.
Cancer: The International Agency for Research on Cancer (IARC) concluded that “crystalline silica inhaled in the form of quartz or cristobalite from occupational sources is carcinogenic to humans (Group 1)” . Other conditions that may be caused by, or aggravated by exposure to airborne respirable silica include scleroderma, tuberculosis, and kidney failure.
Toxic Substances Control Act: Crystalline silica (quartz) appears on the EPA TSCA inventory under the CAS No 14808-60-7. CA Proposition 65: Crystalline silica (quartz) is classified as a substance known to the state of California to be a carcinogen.
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The International Agency for Research on Cancer (IARC)has determined that crystalline silica in the form of quartz or cristobalite that is inhaled from occupational sources is carcinogenic to humans. The National Toxicology Program (NTP) classifies respirable crystalline silica as known to be a human carcinogen. The American Conference of Governmental Industrial Hygienists (ACGIH) classifies crystalline silica, quartz, as a suspected human carcinogen.
Breathing dust containing respirable crystalline silica may not cause noticeable injury or illness even though permanent lung damage may be occurring. Inhalation of dust may have the following serious chronic health effects: Excessive inhalation of respirable dust can cause pneumoconiosis, a respiratory disease, which can result in delayed, progressive, disabling and sometimes fatal lung injury. Symptoms include cough, shortness of breath, wheezing, non-specific chest illness and reduced pulmonary function. Smoking exacerbates this disease. Individuals with pneumoconiosis are predisposed to develop tuberculosis. There is some evidence that breathing respirable crystalline silica or the disease silicosis is associated with an increased incidence of significant disease endpoints such as scleroderma (an immune system disorder manifested by fibrosis of the lungs, skin and other internal organs) and kidney disease.
Every year millions of workers in the U.S. are exposed to crystalline silica. Occupational exposure to crystalline silica dust causes or contributes to the development of silicosis, a disabling, irreversible, and sometimes fatal lung disease. Silica is a natural constituent of the earth's crust and is a major component of sand and granite. Crystalline silica, or free silica, is a term for the chemical compound silicon dioxide (Si02) when it occurs as a crystalline structure. Crystalline silica occurs naturally in many different forms, but the three most common forms are quartz (which is the most abundant), cristobalite, and tridymite.
The most serious exposures result from quartz in the form of respirable dust produced by grinding, sandblasting, and mixing operations. Activities such as jack hammering, rock drilling, concrete mixing, concrete drilling, brick and concrete block or slab cutting and guniting are also associated with potential exposure to crystalline silica dust. Crystalline silica affects the body when it is inhaled by causing fibrosis or scar tissue formation in the lungs. Personal air samples should be collected in the worker's breathing zone to ensure that exposures are kept below the permissible exposure limit (PEL) for silica. The PEL for crystalline silica is dependent on the amount of free silica that is present in the dust generated from the work operation.
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Crystalline silica is a solid substance (also known as quartz) found almost everywhere in the earth's crust. It is present in varying amounts in sand, clays, muds, shale, and in rocks (e.g granite). It is present in the ground in quarries and mines. Crystalline silica (derived from sand) is present in building and construction materials such as cement, concrete, plaster, bricks and tiles. If the dust given off from working with these materials is fine enough to be breathed into the lungs it is termed "respirable".
Under the COSHH Regulations there is a Maximum Exposure Limit (MEL) for respirable crystalline silica (RCS) of 0.3 mg.m-3 (8-hour time weighted average [TWA]). Current evidence indicates that if workers are exposed regularly to 0.3 mg.m-3 there is a much higher risk of lung damage than had been previously thought. The legal requirement for substances with MELs is to control exposure as far below the MEL as is reasonably practicable. In the past some industry sectors had difficulty in controlling exposure to RCS below 0.3 mg.m-3. HSE believes it should now be reasonably practicable for all industry sectors to control RCS to 0.1 mg.m-3 (8-hour TWA). The purpose of this CHAN is to raise awareness among employers and workers about the new evidence on RCS and to advise that employers should aim to control exposures to 0.1 mg.m-3 (8-hour TWA) or below. HSE is not proposing a formal change to the MEL because a new system of Occupational Exposure Limits (OELs) is planned to be in place by the end of 2004 which is likely to overtake any new MEL developments. HSE's intention is to consult on a more stringent OEL for RCS when the new OEL system comes into force.
Where it is used: Workers are exposed to RCS dust in quarries and mines, iron and steel foundries, construction sites, ceramic (including pottery) manufacture, the heavy clay industry and brick making, and stone-masonry. Workers can be also exposed to RCS dust in the manufacture and use of silica flour, which is made by finely milling sand. Silica flour can be used in paints and a variety of other products.
Key health hazard: The key health hazard from exposure to RCS dust is silicosis. Silicosis is a lung disease in which small hard nodules of scar tissue develop in the lungs. The nodules can be seen on chest X-ray. Silicosis can take some years to develop, and even after exposure to RCS dust stops it can get progressively worse. The main symptoms in affected people are difficulty in breathing and cough. In severe cases it can lead to a shortening of life expectancy. Long-term exposures to high levels of RCS dust can also lead to an increased risk of developing lung cancer.
How it gets into the body: RCS enters the body by breathing in the dust through the nose and mouth. Once it is breathed in, RCS dust can be retained in the lungs for many years.
What suppliers should do: You should ensure that the information contained in this notice is passed on to your customers as required by the Chemicals (Hazard Information and Packaging for Supply) Regulations 2002. You should take steps to review your safety data sheets to reflect this information.
What employers should do: You should give priority to preventing your employees being exposed to RCS dust. Where preventing exposure to RCS dust is not reasonably practicable (e.g. by using a different substance), you should adequately control exposure by a combination of engineering and process control measures. HSE believes that in most cases it should be reasonably practicable to control exposure to 0.1 mg.m-3 (8-hour TWA) or less by engineering or process control. Employers should aim to ensure that workers are not exposed to RCS dust concentrations above this level. If exposure cannot be controlled to 0.1 mg.m-3 (8-hour TWA) or below by elimination or process or engineering controls, then exposure must be controlled by provision and use of suitable respiratory protective equipment. In dealing with exposure you should try to reduce the number of people exposed to RCS dust and the length of time each is exposed as required by good hygiene practice. You must give all your employees who are, or who may be, exposed to RCS dust sufficient information, instruction and training to understand the potential problems and the precautions they need to take. You should make sure that employees, safety representatives or representatives of employee safety are aware of this information and are consulted on any action that you propose to take as a result.
What employees should do: You must co-operate with your employer in using the control measures (such as ventilation and personal protective equipment) provided and reporting any defects found in the control measures. You may wish to seek the advice of your safety representative or representative of employee safety.
A detailed HSE review of the scientific evidence relating to the risks of silicosis entitled "Respirable Crystalline Silica - PHASE 1; Variability in fibrogenic potency and exposure-response relationships for silicosis. Hazard Assessment Document." EH75/4, ISBN 0-7176-2374-2 is available from HSE Books
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Exposures to respirable dust and silica were investigated among 36 construction sites in the USA. Personal measurements (n = 151) were analyzed from 80 workers in four trades, namely bricklayers, painters (while abrasive blasting), operating engineers and laborers. Painters had the highest exposures (median values for respirable dust and silica: 13.5 and 1.28 mg/m3, respectively), followed by laborers (2.46 and 0.350 mg/m3), bricklayers (2.13 and 3.20 mg/m3) and operating engineers (0.720 and 0.075 mg/m3). We refer to the likelihood that a typical worker from a given trade would be exposed, on average, above the occupational exposure limit (OEL) as the probability of overexposure. Given US OELs of 0.05 mg/m3 for respirable silica and 3 mg/m3 for respirable dust, we estimated probabilities of overexposure as between 64.5 and 100% for silica and between 8.2 and 89.2% for dust; in no instance could it be inferred with certainty that this probability was less than 10%. This indicates that silica exposures are grossly unacceptable in the US construction industry.
While engineering and administrative interventions are needed to reduce overall air levels, the heterogeneous exposures among members of each trade suggest that controls should focus, in part, upon the individual sites, activities and equipment involved. The effects of current controls and workplace characteristics upon silica exposures were investigated among operating engineers and laborers. Silica exposures were significantly reduced by wet dust suppression (~3-fold for laborers) and use of ventilated cabs (~6-fold for operating engineers) and were significantly increased indoors (about 4-fold for laborers). It is concluded that urgent action is required to reduce silica exposures in the US construction industry.
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Portland cement is one of the most widely used materials in construction. Applications include concrete floors, walls, and pavement; concrete blocks; and different mixtures of mortar and grout. Thousands of construction workers are exposed to concrete every day without harm. But anyone who uses or supervises the use of portland cement should know its health hazards and the safe working procedures necessary to minimize exposure. This article outlines those hazards and makes recommendations on how to use cement safely. Health effects: Cement can cause ill health by skin contact, eye contact, or inhalation. Risk of injury depends on duration and level of exposure and individual sensitivity.
Hazardous materials in wet concrete and mortar include: alkaline compounds such as lime (calcium oxide) that are corrosive to human tissue, trace amounts of crystalline silica which is abrasive to the skin and can damage lungs, trace amounts of chromium that can cause allergic reactions.
Skin contact: The hazards of wet cement are due to its caustic, abrasive, and drying properties. Wet concrete contacting the skin for a short period and then thoroughly washed off causes little irritation. But continuous contact between skin and wet concrete allows alkaline compounds to penetrate and burn the skin. When wet concrete or mortar is trapped against the skin—for instance, by falling inside a worker’s boots or gloves or by soaking through protective clothing—the result may be first, second, or third degree burns or skin ulcers. These injuries can take several months to heal and may involve hospitalization and skin grafts. Cement dust released during bag dumping or concrete cutting can also irritate the skin. Moisture from sweat or wet clothing reacts with the cement dust to form a caustic solution.
Allergic skin reaction: Some workers become allergic to the hexavalent chromium in cement. A small yet significant percentage of all workers using cement will develop an allergy to chromium, with symptoms ranging from a mild rash to severe skin ulcers. In addition to skin reactions, hexavalent chromium can cause a respiratory allergy called occupational asthma. Symptoms include wheezing and difficulty breathing. Workers may develop both skin and respiratory allergies to hexavalent chromium. It’s possible to work with cement for years without any allergic skin reaction and then to suddenly develop such a reaction. The condition gets worse until exposure to even minute quantities triggers a severe reaction. The allergy usually lasts a lifetime and prevents any future work with wet concrete or powder cement.
Eye contact: Exposure to airborne dust may cause immediate or delayed irritation of the eyes. Depending on the level of exposure, effects may range from redness to chemical burns and blindness.
Inhalation: Inhaling high levels of dust may occur when workers empty bags of cement. In the short term, such exposure irritates the nose and throat and causes choking and difficult breathing. Sanding, grinding, or cutting concrete can also release large amounts of dust containing high levels of crystalline silica. Prolonged or repeated exposure can lead to a disabling and often fatal lung disease called silicosis. Some studies also indicate a link between crystalline silica exposure and lung cancer.
Controls: The following are some basic recommendations for handling and using cement safely.
Personal protection: To protect skin from cement and cement mixtures, workers should wear: alkali-resistant gloves coveralls with long sleeves and full-length trousers (pull sleeves down over gloves and tuck pants inside boots and duct-tape at the top to keep mortar and concrete out). Waterproof boots high enough to prevent concrete from flowing in when workers must stand in fresh concrete suitable respiratory protective equipment such as a P, N or R 95 respirator when cement dust can’t be avoided. Suitable eye protection where mixing, pouring, or other activities may endanger eyes (minimum—safety glasses with sideshields or goggles, under extremely dusty conditions, tight-fitting unvented or indirectly vented goggles. Don’t wear contact lenses when handling cement or cement products).
Work practices: When laying concrete block, have different sizes on hand to avoid cutting or hammering to make them fit. Work in ways that minimize the amount of cement dust released. Where possible, wet-cut rather than dry-cut masonry products. Mix dry cement in well-ventilated areas. Make sure to work upwind from dust sources. Where possible, use ready-mixed concrete instead of mixing on site. When kneeling on fresh concrete, use a dry board or waterproof kneepads to protect knees from water that can soak through fabric. Remove jewelry such as rings and watches because wet cement can collect under them.
Hygiene: Clothing contaminated by wet cement should be quickly removed. Skin in contact with wet cement should be washed immediately with large amounts of cool clean water. Don’t wash your hands with water from buckets used for cleaning tools. Provide adequate hygiene facilities on site for workers to wash hands and face at the end of a job and before eating, drinking, smoking, or using the toilet. Facilities for cleaning boots and changing clothes should also be available.
Training: Under the Workplace Hazardous Materials Information System (WHMIS) in force across Canada, workers handling, using, or exposed to dry or wet cement must be educated in hazards and controls.
First aid: Skin contaminated with wet or dry cement should be washed with cold running water as soon as possible. Open sores or cuts should be thoroughly flushed and covered with suitable dressings. Get medical attention if discomfort persists. Contaminated eyes should be washed with cold tap water for at least 15 minutes before the affected person is taken to hospital.
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This study assessed the effectiveness of commercially available local exhaust ventilation (LEV) systems for controlling respirable dust and crystalline silica exposures during concrete cutting and grinding activities. Work activities were performed by union-sponsored apprentices and included tuck-point grinding, surface grinding, paver block and brick cutting (masonry saw), and concrete block cutting (hand-held saw).
Although exposure reduction was significant (70-90% at the low ventilation rate and 80-95% reduction at the high ventilation rate), personal respirable quartz exposures remained very high: 1.4-2.82PEL (permissible exposure limit) at the low ventilation rate and 0.9-1.72PEL at the high ventilation rate. Exposure levels found under actual field conditions would likely be lower due to the intermittent nature of most job tasks. Despite incomplete control, LEV has merit, as it would reduce the risk of workers developing disease, allow workers to use a lower level of respiratory protection, protect workers during short duration work episodes, reduce exposure to nearby workers, and reduce clean-up associated dust exposures.
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| This literature review summarizes engineering control technology research for dust and silica exposures associated with selected tasks in the construction industry. Exposure to crystalline silica can cause silicosis and lung fibrosis, and evidence now links it with lung cancer. Of over 30 references identified and reviewed, 16 were particularly significant in providing data and analyses capable of documenting the efficacy of various engineering controls. These reports include information on generation rates and worker exposures to silica and dust during four different tasks: cutting brick and concrete block, grinding mortar from between bricks, drilling, and grinding concrete surfaces. The major controls are wet methods and local exhaust ventilation. The studies suggest that while the methods provide substantial exposure reductions, they may not reduce levels below the current ACGIH® threshold limit value (TLV®) of 0.05 mg/m3 for respirable quartz. Although further research on controls for these operations is indicated, it is clear that effective methods exist for significant exposure reduction.
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