Some of the more common (and basic) chemical hazards encountered at a precast concrete facility include coatings, form release agents and cement.
By Alex Morales
What’s under your kitchen sink? Or in your garage cabinet?
We store many different chemical products throughout our homes but rarely consider how potentially harmful they can be. The dangers of some products are more apparent than others, thanks to the publicity provided by the media and various other organizations. For instance, we all know that antifreeze has a very sweet taste, often attracting pets, livestock or wildlife, and that it can cause seizures, kidney failure or even death if ingested. And we all know that a mixture of ammonia and bleach produces a deadly chlorine gas.
Although you are not required to possess a Material Safety Data Sheet (MSDS) for each of these products at home, it does exist and you can obtain a copy from your local supermarket or supply store.
In a production facility, however, an MSDS must always be on file when hazardous chemicals are used. Some chemical dangers are apparent to production floor employees due to industry buzz, but other dangers may not be so obvious. That’s why the MSDS is such an important safety measure.
Recent concrete industry buzzwords include “dermatitis,” “VOC” and other terms, but what should these terms mean to the average employee? There are three prominent chemical hazards at any manufactured concrete plant: concrete coatings, form release agents and cement (yes, cement!).
Precast concrete products most often receiving the added protection of coatings include manholes, tanks, vaults and other below-grade products. Coatings are usually separated into two types: exterior and interior.
Exterior coatings are generally used for damp proofing, waterproofing and/or protection from chemical attack. They are often applied at the precast plant prior to being shipped to a job site for installation. They may also be applied at the job site.
Interior coatings are used primarily for protection of the concrete from attack by aggressive substances that can be found in sewer systems, such as hydrogen sulfide.
In the past, coal tar- and/or petroleum-based materials were the most common exterior coatings used for damp proofing and waterproofing. These types of coatings are often hazardous to the health of those applying them, and cleanup and disposal require special precautions to protect the environment. Although there are many better alternatives today, coal tar-based coatings are still prevalent because some specifications that call for their use have not been updated to reflect the availability of more user- and earth-friendly coatings.
Water-based coatings are preferred over coal tar- or other petroleum-based materials. Water-based coatings do not pose health hazards to personnel applying them, and they are environmentally friendly – thus reducing and/or eliminating the necessity for special precautions for cleanup and disposal. They also penetrate the concrete surface more efficiently because capillary action draws the coating into the pores of the concrete, creating a more effective barrier.
Hazardous exposure to coal tar coating may include skin contact, inhalation and ingestion. The International Agency for Research on Carcinogens has designated coal tar epoxy as a cause of cancer. As such, the use of full-body Tyvek suits, appropriate respiratory protection, gloves, face protection and other equipment may be necessary when handling it.
Personal air sampling should be conducted when using a spray coating with hazardous ingredients to determine whether a respiratory protection program should be implemented.
Before handling any concrete coating, you should familiarize yourself with the type of coating and any potential hazards associated with it. Most of the information you need to make a determination is found on the MSDS for that material. A qualified person should review the MSDS and, if necessary, discuss any potential issues with the manufacturer’s representative, including actions to take in case of accidental overexposure. In general, suppliers are eager to discuss their products with you and want to ensure that you handle them properly.
In today’s manufactured concrete market, there are three broad classifications of form release agents:
- Those that provide a barrier between the form and the concrete (petroleum-based products, kerosene, mineral oils waxes, etc.)
- Those that are chemically active (proprietary products, vegetable oil-based products, etc.)
- A combination of both
The effectiveness of each type of release agent largely depends on application, form type and other factors (see MC Winter 2003 for more detailed information on release agent classifications and application rates). When applying release agents or when using spray or fogging application methods for thinner applications, concerns about the hazards associated with them abound.
VOCs (Volatile Organic Compounds) are compounds that create ozone at ground level and contribute to air pollution. Since September 1999, the U.S. EPA has required that VOC emissions be reduced by 113,000 tons per year in the United States. These regulations affect 62 product categories used by the concrete industry, including many types of form release agents.
It is important to be aware of the VOC’s content in all products used in the plant, including release agents, or to assure the materials used are VOC compliant. It is also important to have this information in writing from the supplier and to ask for verification as to how the VOC content was determined.
Method 24 is the EPA’s mandate for testing, and although it was originally designed for coating materials, all steps should be followed when testing release agents in order to get correct results. It is always in the precaster’s best interest to ensure that the VOC tests were run by reputable EPA-certified laboratories.
There are many form release agents on the market that conform to VOC regulations; however, users should familiarize themselves with the release agent they are using and know how to handle possible overexposure incidents. The MSDS provides a wealth of information and generally includes ACGIH (American Conference of Governmental Industrial Hygienists) threshold limit values and OSHA Permissible Exposure Limits. Section III of the MSDS provides this information and also lists any hazardous ingredients contained in the product. In some cases, these and other chemicals used in the plant are eye irritants, skin irritants and/or cause nausea if accidentally ingested.
Users must also be mindful of the flammability rating of any fuel-type barrier products and avoid flames (including cigarettes and lighters/matches) when using them. The MSDS provides the flammability rating of the material being used. The HMIS (Hazardous Material Identification System), under Section II of the MSDS, has surface information.
For example, if the flammability rating is 3, then the material has a flash point of less than 140 F and is considered flammable. Be sure that your facility’s labeling program includes identifying the health, reactivity, flammability and other hazards associated with the use of the material. Materials with a flash point of between 141 F and 200 F are considered combustible (flammability rating 2) and materials with a flash point in excess of 200 F are listed as a slight hazard of flammability and will have a 1 designation for flammability.
HMIS identification labels on all containers give everyone basic information of the hazards of material being used (see sidebar, “Hazardous Material Identification System”).
As local and state regulations are sometimes more stringent than federal regulations, check with your local authorities (including your state’s Department of Transportation or applicable Canadian equivalent) as to what requirements are in place for your area for transportation of flammable and combustible materials.
From an environmental standpoint, stormwater runoff is another concern; most concrete producers are subject to contamination regulations. Managers should remain aware of local and state regulations to avoid potential problems. Also, keep in mind that some U.S. states have more stringent rules on VOC and stormwater regulations than does the federal EPA.
Unlike concrete coatings and release agents, cement does not have any new regulation-compliant hybrids or variations that can virtually eliminate potential skin contact hazards. As a result, dermatitis issues abound concerning cement contact. Wet cement is a highly basic material with a pH of approximately 12.5 and contains traces of a compound known as hexavalent chromium, which contributes to allergic dermatitis.
Recent research has identified two types of dermatitis: irritant and allergic. Dermatitis is an inflammation of the skin caused by an irritant, such as a chemical, and is not itself necessarily an indication of an allergy. However, approximately 20 percent of dermatitis cases are caused by an allergic reaction. More importantly, a worker can become allergic to cement after repeated exposure over a period of as little as a few days to as long as a few years, and these types of allergies typically are permanent once developed.
Although many different organizations have committed to conducting more research on dermatitis issues, these preliminary findings highlight the importance of eliminating unnecessary exposure to wet cement. If a worker is not now allergic to cement, he or she may eventually develop such an allergy if direct contact persists. In order to protect and maintain healthy skin, workers should:
- Wear clean gloves, face shields and other PPE
- Wash skin with mild soap before and after using gloves and other PPE
- Wash skin immediately if exposed to fresh concrete, even if they do not sense any irritation
- Dry skin with clean paper towels, since air dryers can contribute to further irritation by drying out the skin
- Avoid using hand creams or lotions, since they can prevent the cement from completely washing away
- Practice good housekeeping and maintain a clean work area
It is important to recognize portland cement as a chemical and to handle it carefully (covered in OSHA regulations).
In addition, cement contains respirable silica compounds, and the possibility of developing silicosis is always present (see MC Special Edition 2001 for more information on the nature of silicosis and determining degree of risk). Silicosis is caused only by the inhalation of small particles of free silica dust. The best method for preventing employee exposure is to implement engineering and administrative controls. Some popular controls to limit exposure include:
- Wet cutting of hardened concrete
- Installing dust control systems
- Limiting exposure time
- Preparing a well-designed housekeeping program
- Use of respiratory equipment
It is important to educate employees about this and other potential hazards to better equip them to identify potential safety hazards.
This brief review of chemical hazards is not exhaustive. There may be many other potential hazards at your facility depending on the unique production processes and chemicals used at your plant. Just like no two households have the same chemical products underneath the sink, no two precast facilities have identical chemical safety concerns. Every precast facility is different; each will have unique potential safety hazards and will need its own unique safety plan.
Hazardous Material Identification System
The HMIS label is a four-part label encompassing red, blue, yellow and white sections.
Red – Flammability Rating (0 to 4): If this rating is a 2 or 3, then an additional red diamond label, labeled “Flammable or Combustible,” is required, as shown in the illustration.
Blue – Health Rating (0 to 4)
Yellow – Reactivity Rating (0 to 4)
White – Personal Protection Rating (A to X)
OSHA Hand Protection Standards
OSHA Standard 29 CFR 1910.138 includes these entries about hand protection.
(a) General requirements. Employers shall select and require employees to use appropriate hand protection when employees’ hands are exposed to hazards such as those from skin absorption of harmful substances; severe cuts or lacerations; severe abrasions; punctures; chemical burns; thermal burns; and harmful temperature extremes.
(b) Selection. Employers shall base the selection of the appropriate hand protection on an evaluation of the performance characteristics of the hand protection relative to the task(s) to be performed, conditions present, duration of use, and the hazards and potential hazards identified.
Release Agent Precautions
Here are some additional precautions concerning release agents.
• If hand-held form oil sprayers are used, pressure relief devices may “gum up” and stick.
• Sudden release of form oil may result if a sprayer is pressurized higher than a safe level and the pressure relief frees itself.
• Potential eye injury is possible due to form release blowing out.
• Eye wash stations should be located at accessible areas to provide 15 minutes of flushing time.
• Eye wash facilities should comply with ANSI regulations.