Issues

Controlling Chemical Hazards

Water and wastewater treatment workers come into contact with chemicals every day at work. The chemicals are delivered in 55-gallon drums, small plastic containers, boxes containing powders and in other forms. Some dangerous chemicals in your workplace are not in containers. Asbestos fibers can be in pipe insulation. Lead can be in dust that contains lead paint or in welding fumes from metal coatings.

Chemicals can be in different forms. The way a chemical might enter your body depends on the form of a chemical:

  • Dusts, fumes and certain fibers are small solids (particulates) which may be inhaled or swallowed.

  • Liquids can harm skin and also be absorbed through the skin.

  • Mists are very small droplets of liquids that are inhaled.

  • Gases and vapors are inhaled.

Getting information about chemicals on the job — Right-to-know laws

The Right-to-Know refers to workers’ rights to information about chemicals in their workplaces. The federal law that provides these rights is the OSHA Hazard Communication Standard (29 CFR 1910.1200). Private sector employers must provide chemical information to their workers under the OSHA standard.

Most states have their own Right-to-Know laws that cover public-sector workers. In some of these states, workers have stronger rights than under the federal Hazard Communication Standard.

Know your right-to-know rights!

Right-to-Know laws give workers the right to know about dangerous chemicals at work. You have rights to get information about chemicals in four main ways.

  1. EMPLOYERS MUST MAINTAIN A LIST OF ALL HAZARDOUS PRODUCTS KNOWN TO BE IN THE WORKPLACE.

  2. CHEMICAL CONTAINERS MUST HAVE LABELS.

    • Containers must have a label that workers can read.

    • The label must show what the product is and who makes it.

    • The label must warn about the dangers of the chemical.

  3. MATERIAL SAFETY DATA SHEETS (MSDS) THAT DESCRIBE THE DANGERS OF A CHEMICAL AND HOW TO PREVENT EXPOSURE MUST BE PROVIDED.


    • Workers must have access to MSDSs for the chemicals they work with during their shift.

    • MSDSs must not have blank spaces.

    • The name of the product on the MSDS must match the name on the
      container’s label.

  4. WORKERS MUST BE TRAINED ABOUT CHEMICAL HAZARDS



    • What are the health hazards of a chemical.

    • How to handle and store chemicals.

    • How to prevent exposure to chemicals.

    • Workers’ rights and employers’ duties under the law.

Workers' rights to information under hazard communication

Under the Hazard Communication Standard, employers must provide their workers with information about chemicals by:

  • a written program to inform workers, including a list of hazardous chemicals;

  • labels;

  • material safety data sheets; and

  • training.

Some AFSCME local unions have formed Hazardous Materials Review Committees. They look at the MSDS and other information on chemicals before the employer brings them into the workplace. The committee checks the products’ hazards and may try to find safer substitutes for dangerous chemicals. These review committees often work as joint labor/management efforts.

Hazardous Chemicals List

Employers must keep an updated list of hazardous chemicals they use and store. A hazardous chemical is a product that can cause harm to workers.

Labels

The OSHA Hazard Communication Standard requires that manufacturers must label all chemical containers. At a minimum, the OSHA standard requires that the label must contain at least three pieces of information:

  • All labels must identify the chemical product. Either the chemical name or the brand name of the product may be used.

  • All labels must include the manufacturer’s name and address.

  • All labels must carry a warning about the specific health and safety hazards of the product. For example, “Absorbed through Skin — Causes Kidney Damage” tells what part of the body may be harmed. This is better than a label that advises to “Avoid contact with skin.” OSHA requires that the label list the organs that are affected by the chemical (target organ).

The OSHA Hazard Communication Standard also requires that:

  • Labels must be placed on smaller containers when workers transfer material from one container to another. For example, if a worker transfers one gallon from a 55-gallon drum into a smaller container, the smaller container must also have a label. EXCEPTION: The smaller container does not have to have a label if only that worker will use up all the material on his/her shift. AFSCME recommends that employers label ALL chemical containers.

  • All labels must be written in English. Labels in other languages are acceptable as long as there is an English label as well.

  • Labels can be read. Damaged labels must be replaced before the product may be used.

Chemicals do not always have to be labeled. For example, employers do not have to label pipes or piping systems. Employers must still inform employees about hazardous chemicals in pipes, such as gas or steam. This can be done by color-coding pipes, such as painting all gas pipes yellow.

Material Safety Data Sheets (MSDS) and workers' access

The law requires the chemical manufacturer to send Material Safety Data Sheets or MSDS along with the chemicals. The MSDS must not have any blank spaces. If there is no information for a section, the space must say unknown or not applicable (N/A).

Workers have the right to review the MSDS. Right-to-know laws require that workers have access to an MSDS for each hazardous chemical in their work area during their shift! For example, an MSDS cannot be kept in a day-shift supervisor’s office if the office is locked and workers on the evening or night shift cannot get the sheets.

How to get an MSDS if you are not covered by OSHA or a state right-to-know law:

Information Required on Material Safety Data Sheets

An MSDS does not have to be on a specific form. However, right-to-know laws require that an MSDS contain certain types of information.

Section 1. Product Identity

  • The name of the chemical on the MSDS must match the name on the label.

  • The name and location of the manufacturer and when the MSDS was
    produced.

Section 2. Hazardous Ingredients and Exposure Limits

Products are usually a mixture of different chemicals. Many chemical products contain water or other substances that are not dangerous. These do not have to be listed on the MSDS.

  • The MSDS must list all the chemicals that can cause harm.

  • The MSDS must include legal and recommended exposure limits.

Permissible Exposure Limits (PELs)

The Occupational Safety and Health Administration (OSHA) has rules to limit workers’ exposure to hundreds of chemicals. These limits are called Permissible Exposure Limits or PELs. These are the exposure levels that OSHA can legally enforce. In other words, these are the exposure limits that are allowed (permissible).

The amount of a chemical a person is exposed to is usually measured in parts per million or ppm. For every one million parts (molecules) of air, there can be a certain number of parts of a chemical. For example, the permissible exposure limit for carbon monoxide is 50 parts per million. There can be up to 50 molecules of carbon monoxide in every million molecules of air that a worker breathes. One part per million is equal to one drop of water in 18 gallons of water, or one inch in 16 miles.

The amount of exposure allowed also depends on how long a worker is exposed to a chemical. PELs are figured on an exposure for a full 8-hour shift. This is called an 8-hour Time-Weighted-Average or TWA. For example, the permissible exposure level for carbon monoxide is 50 parts per million averaged over an 8-hour day. This means a worker could be exposed to 400 parts per million of carbon monoxide on one shift (50 parts per million x 8 hours).

Short Term Exposure Limits (STELs) and Ceiling Limits

Some chemicals are so dangerous that the exposure limits cannot be averaged over a full shift. Instead, the short term exposure limits are based on 15- or 30-minute periods.

Other chemicals, like carbon monoxide, have ceiling limits. The ceiling limit for carbon monoxide is 200 parts per million. This means that a worker can not be exposed to over 200 parts per million at any time.

LEGAL DOES NOT MEAN SAFE!!!

A legal exposure to a chemical does not mean that workers will not get sick. Some workers are very sensitive to certain chemicals and may get ill at exposures well below the PEL. For chemicals that cause cancer, there is no level of exposure that is known to be totally safe for everyone.

Recommended Exposure Limits

Other organizations provide guidance on limiting exposure to chemicals. These may differ from OSHA’s limits. The National Institute of Occupational Safety and Health (NIOSH) is a government agency that does research on job hazards. NIOSH has a list of Recommended Exposure Limits or RELs. The American Conference of Governmental Industrial Hygienists (ACGIH) limits are called Threshold Limit Values or TLVs.

Section 3. Chemical Characteristics

  • The temperature a chemical evaporates into the air (boiling point).

  • Whether a chemical vapor will rise or sink in the air (vapor density).

Section 4. Fire and Explosion Information

  • The way to safely put out a fire if the chemical ignites.

  • If there are any unusual fire or explosion hazards.

  • The lowest temperature at which a chemical vapor will light on fire (flashpoint).

  • The amount of a chemical vapor that must be in the air to burn (lower explosive or flammable limit and the upper explosive or flammable limit).

Section 5. Reactivity

  • Whether a chemical is stable and what conditions to avoid.

  • Other chemicals or materials to avoid mixing together.

Section 6. Health Effects

  • The way a chemical enters the body (breathing, swallowing, skin absorption).

  • The immediate and long-term health effects that might occur.

  • Whether the chemical causes cancer or birth defects.

Section 7. Handling and Storing Instructions

  • What to do in case of a spill.

  • How to safely store and dispose of the chemical.

Section 8. Preventing Exposure (Control Measures)

  • The type of ventilation that is needed to work with the chemical.

  • The type of respirator, glove or other equipment to use when working with the chemical.

Training

Workers must receive training on the chemicals they use or work around. The training must include:

  • the health hazards caused by the chemical;

  • how to handle and store chemicals;

  • how workers can protect themselves from exposure to chemicals; and

  • workers’ rights and employers’ duties under the law — such as where to find the MSDSs in the workplace and how to read them.

Other ways to find out if workers are exposed to chemicals

Not all chemicals come in a labeled container or with an MSDS. There are a number of ways to find out what dangerous chemicals are in your workplace.

Air monitoring

Area sampling measures what is in the air in an area. Personal sampling measures a worker’s exposure to a chemical. The air that is tested is taken close to the worker’s nose and mouth (breathing zone).

Confined space monitoring must be done before entry. Workers must know if there are hazards in the air before they do their jobs. For example, there can be deadly gases in manholes or other confined spaces. Before a worker enters the space, the air must be tested to make sure there is enough oxygen to breathe and there are no chemical hazards.

Note: OSHA gives workers the right to observe monitoring to determine that it was done at the correct time and under the correct conditions.

Bulk and wipe samples

A bulk sample is a test to see if a material contains a dangerous substance. For example, building materials such as pipe insulation, flooring or fireproofing should be tested to see if they contain asbestos. A wipe sample is a test to find out if dust contains lead, asbestos or other dangerous particles.

Biological monitoring

There are tests to find out if chemicals have entered and have been stored in workers’ bodies. For example, blood tests are used to measure exposure to lead. Chest X-rays can show exposure to asbestos or silica.

Preventing exposure to chemicals

As with all types of dangers, the best approach is to remove the hazard. Chemical hazards can be removed or controlled in different ways.

Substitution

Use less dangerous chemicals. Employers should consider the health effects as well as price and other factors when buying chemicals. Whenever possible, employers should avoid buying or using chemicals that cause cancer. Another way to remove toxic chemicals is to do jobs without chemicals. For example, grass can be mowed rather than spraying toxic pesticides.

Engingeering controls

Enclose (Isolate) the Job
Ventilation

Administrative controls

Hazards can be reduced by keeping work areas neat and clean. Part of the workday should be spent keeping the workplace orderly by doing routine tasks such as:

  • putting rags soaked with chemicals in closed containers;

  • storing chemicals properly in clearly labeled containers;

  • keeping only the amount of chemical on hand that is needed; and/or

  • cleaning chemical spills right away.

Workers need the supplies, time and procedures to keep chemicals off their clothes and bodies. Employers should provide:

  • a separate room away from work areas for eating and storing food;

  • soap and water for washing;

  • time to wash before breaks, before eating and at the end of the shift;

  • a place to change and store street clothes; and

  • a facility to wash work clothes.

Personal Protective Equipment (PPE)

Masks, gloves and other personal safety gear are the least effective ways to protect workers. The protective gear does not remove the chemical hazard from the area. If the gear does not work, then the worker gets no protection. PPE is needed if there is no other solution, or until a better control is installed. Often, PPE is used along with other protections.

The type of respirator, glove or other type of PPE that workers need depends on the chemical in the area. Respirator cartridges that are used with air-purifying respirators are color coded according to hazard.

 RESPIRATOR CARTRIDGE SELECTION
COLOR OF CARTRIDGE = TYPE OF TOXIC CHEMICALS

 Black  organic vapors such as acetone, methanol, methyl ethyl ketone
 White   chlorine, hydrogen chloride, sulfur dioxide, chlorine dioxide, hydrogen sulfide (escape only)- these are acid gases
 Yellow  organic vapors and acid gases including chlorine, hydrogen chloride, sulfur dioxide, or hydrogen fluoride
 Green  ammonia, methylamine
 Pink or Purple  (HEPA - High Efficiency Particulate Air) asbestos, lead, toxic dusts, fumes, mists
 Brown  varies — see manufacturer’s product information on package or side of the cartridge. Usually for formaldehyde.
 Gray  varies — see manufacturer’s product information on package or side of the cartridge.

Chemicals used in the treatment process

Chlorine

Chlorine is the most common toxic chemical used in sewage treatment plants and is available in gaseous, liquid or granular form. It is used to control odors in the sewers, wet wells and headworks; insect and larvae control in trickling filters; settling aid; and grease removal. A yellow-green gas, chlorine is usually stored under pressure in cylinders. Because of its extreme toxicity, everyone who works around chlorine should be fully trained in its proper use and emergency procedures.

All efforts should be made to prevent direct worker exposure to chlorine. It is heavier than air and will flow along the ground and spread. Exposure to very low levels of chlorine (1-3 ppm) may cause stinging or burning sensations in the eyes, nose and throat; 30 ppm will trigger harsh and serious coughing spells. At higher levels, workers may experience bleeding of the nose and throat. Workers repeatedly exposed to low levels of chlorine may be more susceptible to respiratory infections and suffer corrosion of the teeth. Exposure to chlorine may aggravate heart conditions.

Chlorine attacks the respiratory system. Those who have respiratory problems, asthma, bronchitis, emphysema or suffering from cold or sinus conditions are susceptible to chlorine inhalation. Short-term health effects can include nausea, vomiting, dizziness, shortness of breath and chest pain. Skin contact may cause burn, irritation and blisters.

 STRICT PRECAUTIONS MUST BE TAKEN
IN THE STORAGE AND USE OF CHLORINE.

  • Chlorine cylinders should be stored in covered, well ventilated storage spaces that are separate from chlorinators and free of combustible materials. They should not be crowded or exposed to high heats. Cylinders should always be stored vertically with the valve on top. All pipe lines for conveying chlorine should be extra heavy with non-corroding valves.

  • Workers who handle cylinders should be trained in proper techniques and provided with approved wrenches for engaging cylinder valves. The wrong sized wrench can cause valves to malfunction and leak. Workers should wear full face respirators while changing cylinders. Impervious gloves and protective clothing must be worn when working with liquid chlorine.

  • Ideally, operators of chlorinators should have a separate, enclosed operations room with positive ventilation which prevents the gas from seeping in when the door is open. Where this is not possible, chlorinator rooms must have positive ventilation provided at the floor levels (as chlorine gas is heavier than air). Ventilation controls for these rooms should be outside so that the operator can activate the ventilation before entering the room. Self-contained breathing units should be available immediately outside the room. It is desirable to have a window for observation of the chlorine room so that entering the room is not always necessary.

  • There should be a routine inspection procedure in the plant to inspect for leaks in pipes, feed lines, chlorine pressure gauge connectors and joints between supply tanks and chlorine pressure reducing valves. Inspectors should check for smell, discoloration, water formation or rust spots. Leaks must be repaired immediately or they will get worse. Because even extremely small leaks can be dangerous, the best way to detect leaks or monitor chlorine gas is to use an electronic chlorine leak detector with an alarm that is capable of detecting leaks at very low levels. Leaks can also be detected by spraying liquid ammonia on the tanks. Ammonia forms a white vapor (ammonium chloride) on contact with chlorine. Any worker engaged in this process or who directly handles chlorine cylinders should be provided with impervious clothing, gloves and face shields.

  • Water should be kept away from chlorine cylinders at all times. Water mixed with gaseous chlorine at a leak site will form hydrochloric acid and further corrode the cylinder wall, enlarging the leak.

  • Emergency procedures should be developed for chlorine leaks. Plant personnel should be acquainted with and have posted the telephone numbers of the local fire department, industrial emergency and response teams who are experienced in handling chlorine emergencies. All facilities that use chlorine must be equipped with the proper repair kit as specified by the Chlorine Institute. Annual training of repair personnel must be conducted in the use of the repair kits.

WARNING!
Adding chlorine to sewage that contains gasoline, ammonia or sulfur may cause an explosion or fire. Operators should not add chlorine to water containing these substances until they have been sufficiently diluted with influent.

Chlorine Dioxide

Chlorine dioxide is an unstable and explosive gas. It is generated on site when using sodium chlorite and chlorine. Compared to chlorine, chlorine dioxide is expensive and complex to operate and maintain.

Ferric Chloride

Ferric chloride is one of the most common sludge dewatering agents. It decomposes into hydrochloric acid in the presence of light or moist air and is, therefore, extremely corrosive. Ferric chloride can be irritating to the eyes, nose, throat and lungs. Workers who add ferric chloride to sludge and those working in vacuum filtration should be provided with full face cartridge respirators, splash-proof acid resistant goggles, rubber suits, boots and gloves. Emergency eye-wash fountains and safety showers should be located within a 25-foot radius of where ferric chloride is used and stored. Respirators must be available in the event decomposing ferric chloride acid fumes accumulate in storage and use areas.

Similar precautions should be taken for other sludge treatment chemicals such as ferrous sulfate, sulfuric acid, chlorinated coppers and permanganates.

Sulfur Dioxide

Sulfur dioxide is also very dangerous. Sulfur dioxide reduces chlorine by forming sulfuric and hydrochloric acid. It is colorless, heavier than air and corrosive to metals when exposed to moisture. Sulfur dioxide also causes respiratory problems and is irritating to the nose, throat, eyes and lungs.

Sodium Hypochlorite

Sodium hypochlorite (liquid chlorine) is a potential fire and explosion hazard, and is extremely irritating to the eyes, skin, mouth and lungs. Prolonged exposure can burn skin and permanently damage eyes and lungs. Workers who handle containers of sodium hypochlorite should be provided with impervious clothing, gloves and splash-proof goggles. Areas where sodium hypochlorite is used should be equipped with emergency eye-wash fountains. For safety precautions, see the box on chlorine.

Ozonation

Ozone in wastewater treatment is used for disinfection and odor control. It is produced on site from air or oxygen-carrier gas passing between narrowly spaced electrodes under high voltage. Contact with ozone or vapors may cause serious respiratory problems.

Pipe Grouts

Pipe grouts should always be used with plenty of ventilation or respirators. Pipe grouts used for pipe construction or repair can contain two highly toxic chemicals:

  • 2-Nitropropane can cause bleeding of the gastrointestinal tract, severe heart and kidney damage, fluid in the lungs and may cause cancer.

  • Acrylamide (also used in polymers) can cause severe damage to the central nervous system and may cause cancer.

Do not use grouts containing acrylamide.

 

Chemicals used for treating sludge

Chemicals are used to stabilize sludge, remove water and reduce or kill agents that cause disease. Commonly used chemicals include polymers, lime acid caustic and metal salts. Chemical dust can cause irritation to the eye, nose, throat and lungs. Employees working in this area should used personal protective equipment.

Polymers

Polymers are used for sludge conditioning. Polymer vapors can irritate the eyes, nose and skin. Splashing the liquid into the eyes can cause chemical burns. Polymers are also very slippery, causing a walking surface hazard. Some polymers give off ammonia and formaldehyde fumes, and some contain traces of acrylamide, which can cause cancer and severe nerve damage.

Lime

Workers need personal protective equipment when working with lime. This should include gloves, eye protection, respirators, long-sleeved shirts with collars and long pants. Lime must be stored in dry areas to prevent moisture absorption. Contact with a small amount of water may cause fire.

Acids

Hydrochloric, nitric, phosphoric and sulfuric acids are used to adjust pH and to clean equipment. When acid comes in contact with the moist parts of the body, severe burns can result. Always use the proper personal protective equipment when handling acids.

Caustic Chemicals

Commonly caustic chemicals used for sludge conditioning are calcium hydroxide, sodium hydroxide and calcium oxide. The chemicals are used to aid coagulation, adjust pH, clean filter and neutralize acid spills.

Metal Salts

Metals are used for sludge conditioning, biological nutrients, neutralization, filter aids, coagulant aids and settling aids. The metal salts that are commonly used are ferric chloride, ferrous chloride, ferric sulfate, ferrous sulfate and aluminum sulfate. Contact with skin, mouth or eyes can cause severe burns.

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