A mortarless masonry wall system are made from dry-stacked units that can be subsequently grouted, partially grouted, or surface bonded.
Hazard Analysis — Skin contact with Portland cement
Workers who lay or set brick, block, or stone may face hazards from skin contact with portland cement. Portland cement is an ingredient in the following materials:
Portland cement contains hexavalent chromium which causes allergic dermatitis. Prolonged contact with wet cement also causes skin irritation and burns.
Workers who are exposed to Portland cement and products containing Portland cement can get occupational skin diseases. Due to the cement's abrasive, alkalinic, and hygroscopic (drawing moisture from the skin) properties, the occupational skin diseases may include irritant contact dermatitis, allergic contact dermatitis and caustic burns.
- Irritant (non-allergic) contact dermatitis includes redness, stinging, pain, dead skin, blisters, scabs, fissures, swelling, bumps, dry skin and watery discharge.
- Allergic contact dermatitis is a problematic immunologic reaction due to sensitizers.
Sensitizers in workplace materials may cause an allergic response in which the immune system fights off a foreign substance. This type of reaction may be local or widespread. Usually, the material causes no change on first contact. Once a person is sensitized, small amounts can trigger a strong reaction.
The primary sensitizer in Portland cement is hexavalent chromium (hexchrom or Cr[VI]). Thus, when a worker is sensitized while working with Portland cement - either from a single or repeated exposures, that worker's immune system will overreact to a small amount of Cr(VI).
- Caustic burns, also referred as cement burns, are chemical burns caused by the wet cement's alkalinic nature. Second or third degree burns may occur after relatively short exposures to fresh mortar, concrete, grout , and other Portland cement products (including cement-based epoxy resin systems). Cement burns look like other burns. They produce blisters, dead or hardened skin, or black or green skin. In severe cases, these burns may burn down to the bone and cause scars or disability. Cement burns can lead to allergic dermatitis. In addition, chromate sensitivity can exacerbate the severity of cement burns.
Level of Risk:
Portland cement is estimated to account for 25% or more of all work-related skin problems worldwide. Some 5 to 15% of workers coming into contact with Portland cement that contains hexavalent chromium may suffer allergic contact dermatitis, a rate as high as 25 times that of the general population. This dermatitis may persist in 20 to 40% of workers without further exposures, even after they leave the trade.
There are no studies that indicate how many construction workers have allergic dermatitis, or how many will develop it in any given year, in the United States. We do have some information from workers compensation claims, but the true rate of dermatitis is certainly higher than the number of dermatitis claims to workers compensation, for research has shown that most occupational diseases are under-reported.
In Oregon between 1990 and 1997 the claim rate to workers compensation was 7/100,000 construction workers, and a study from Germany found a similar incidence. A study in Finland found that almost 9% of concrete prefabrication workers had work-related hand dermatitis. Among construction workers with skin problems 65% of the dermatitis was caused by work, with 40% being allergic to chromium, 10% to nickel, and 7.5% to epoxy resins in one study. In the German study noted above, the incidence of dermatitis among tile setters and terrazzo workers was 10 times that of a low risk construction occupation.
Bock M, Schmidt A, Bruckner T, Diepgen TL. Occupational Skin Disease in the Construction Industry. Br J Dermatol. 2003 Dec;149(6):1165-71.
Conde-Salazar L, Guimarans D, Villegas C, Romero A, Gonzalez MA. Occupational Allergic Contact Dermatitis in Construction Workers. Contact Dermatis, 1995, 33, 226-230.
Halbert, AR et al. Prognosis of occupational chromate dermatitis. Contact Dermatitis 27: 214-219, 1992.
McCall BP, Horwitz IB, Feldman SR, Balkrishman R. Incidence Rates, Costs, Severity, and Work-Related Factors of Occupational Dermatitis: A Workers' Compensation Analysis of Oregon, 1990-1997. Arch Dermatol. June 2005,141:713-718.
Roto P, Saino H, Reunala T, Laippala P. Additions of Ferrous Sulfate to Cement and Risk of Chromium Dermatitis among Construction Workers. Contact Dermatitis. 1996 Jan;34(1):43-50.
Some tools you can use to measure the risk for dermatitis in this task, where skin contact with mortar and cement is common, include observation to see how much skin contact occurs, asking workers about skin symptoms, and pH tests of surface skin.
Here are some tools you can use to measure the risk for dermatitis, and find ways to reduce the risk. You might also think of other tools.
- Observations and reports of work/personal practices
- Symptoms checklist
- pH tests of surface skin
Consider comparing your group of workers with themselves before and after beginning a program to reduce dermatitis. Use written checklists. Watch your employees' work practices and take reports from them of what they do with a before and after comparison. Which best practices are the employees currently doing? Which are they failing to do? Keep a written record of observations. Have employees complete a symptoms checklist of the skin problems they currently have, with no names attached. Ask them to do a pH test of surface skin. Once you have a baseline record, then begin the effort to reduce skin problems. Take the same measurements periodically to assess progress. The results can help you adjust the efforts.
Best Practices Checklist
|___ 1. Wash with clean running water and pH-neutral soap.|
|___ 2. Wear correct gloves.|
|___ 3. Wash before putting on gloves.|
|___ 4. Wash again whenever gloves are removed.|
|___ 5. Use disposable gloves or clean reusable gloves daily.|
|___ 6. Remove gloves properly.|
|___ 7. Wear glove liners.|
|___ 8. No jewelry at work.|
|___ 9. Long sleeves buttoned or taped inside gloves.|
|___ 10. Rubber boots with pants taped inside for concrete work.|
|___ 11. Never let cement remain on skin or clothes.|
|___ 12. Avoid barrier creams|
|___ 13. Avoid skin softening products at work.|
|___ 14. Change out of work clothes before leaving jobsite.|
|___ 15. See a doctor for any persistent skin problem|
|___ 1.||Check if you had at least one skin problem during the last 12 months|
|___ 2.||Check if you currently have the skin problem.|
|___ 3.||If you have a skin problem, check all the words that apply|
Normal skin is pH 4.5 to 5.5, meaning it is moderately acidic. Contact with wet cement changes skin pH to alkaline. At alkaline pH, skin barrier repair is slowed, damage is prolonged, and skin problems are worsened. Testing skin pH with pH indicator papers/wipes will help determine if the worker or workers are at risk for contact dermatitis.
Worksite conditions can determine whether a worksite material will cause skin problems.
- How long does the material contact the skin?
- How often does a worker use the material?
- Is there mechanical trauma or abrasion of the skin (a break in the barrier)?
- Is the material trapped or occluded to the skin with gloves, creams, lotions, petroleum jelly, or barrier creams?
- Are there adequate hygiene facilities?
Environmental factors can cause skin problems directly or they can work with other factors to increase skin problems:
- Heat causes sweating. Sweat dissolves chemicals and brings them into closer contact with the skin. Heat increases blood flow at the skin surface and increases absorption of materials into and through the skin.
- Cold dries the skin and causes microscopic cracks. Cold changes blood flow at the skin surface and leads to loss of feeling.
- Humidity increases sweating. High humidity keeps sweat from evaporating. Extremely low humidity can dry skin as sweat evaporates.
Individual factors can affect work-related skin problems. These include:
- Pre-existing dermatitis
- Genetic predisposition
- Personal behavior/workpractices
Regulations & Standards:
OSHA standard 1926.28, titled Personal Protective Equipment, in safety and health regulations for construction must be in place. The employer is responsible for requiring the wearing of appropriate personal protective equipment in all operations where there is an exposure to hazardous conditions or where this part indicates the need for using such equipment to reduce the hazards to the employees.
OSHA standard 1926.59, titled Hazard Communication, in safety and health regulations for construction must be in place. The purpose of this section is to ensure that the hazards of all chemicals produced or imported are evaluated, and that information concerning their hazards is transmitted to employers and employees. This transmittal of information is to be accomplished by means of comprehensive hazard communication programs, which are to include container labeling and other forms of warning, material safety data sheets and employee training.
Regulations adopted by a state must be at least as protective as the corresponding federal standard. Work may also be subject to rules of other federal, state and local agencies. Even where there is no hazard specific standard, OSHA prohibits employers from to work in surroundings or under working conditions which are unsanitary, hazardous, or dangerous to his health or safety.
Federal OSHA Standards are enforced by the U.S. Department of Labor in 26 states. There are currently 22 states and jurisdictions operating complete State plans (covering both the private sector and state and local government employees) and 5 - Connecticut, Illinois, New Jersey, New York and the Virgin Islands - which cover public employees only. If you are working in one of those states or jurisdictions you should ensure that you are complying with their requirements.
Substitution, wearing PPE and good work practice can help protect your skin from solvents, adhesives and other chemicals.
BIM is a concept that offers software application to integrate building information for hazard identification and safety planning.