Good judgement in handling laboratory chemicals is of the foremost importance to protect yourself, others, and equipment when working in the laboratory. Laboratory hazards have many different forms. These are covered very well in 29 Code of Federal Regulations 1910.20. In this manual we will concentrate on the more common hazards experienced in laboratories analyzing samples from wastewater treatment facilities.
Personal safety in the laboratory is the responsibility of the analyst. Gloves should be worn when handling chemicals and when processing wastewater samples. Safety glasses must always be worn when handling acids and bases or when making solutions that may splatter out of the container. Other personal protective equipment (PPE) may be appropriate (hand, respiratory, face, etc.), refer to the individual Material Safety Data Sheets (MSDS) for the material to determine what equipment may be necessary or prudent.
All chemicals should be considered potentially dangerous. The safety hazards associated with any chemical should be reviewed before working with chemicals which the analyst is unfamiliar.
Frequent hand washing is expected, especially after handling samples, before and after food preparation, and after using the toilet. Wear proper clothing to protect the skin, the use of a laboratory coat or apron can also help to protect your personal clothing. Shoes that completely cover the feet should be worn in the laboratory. The use of contact lenses in the laboratory is strongly discouraged. Clean up all spills immediately and regularly disinfect the work area (the bench tops).
It is recommended that a "safe" area be established for laboratory personnel to perform calculations. This area should be reasonably removed from the vicinity of sewage, chemicals, or other hazardous substances. The establishment of such an area will protect the laboratory analyst as well as any non-laboratory personnel that may enter the area. Food and beverages should not be brought into the laboratory, or if they are they should be restricted to this area.
Pipetting by mouth is strongly discouraged. Suction or pipette bulbs are inexpensive, easily attainable, and can be mastered easily.
Any and all unsafe acts or conditions should be corrected expeditiously to prevent an accident before it occurs.
It is strongly recommended that the inherent dangers in the laboratory be evaluated for possible problems before those problems manifest themselves. It is prudent to assess such items that may hamper or impair access to the physical plant and make any necessary arrangements that will expedite the response time of any emergency personnel. A list of emergency phone numbers (fire, rescue, poison control, etc.) should be posted by most if not all telephones with the address of the facility to reduce errors in the event of an emergency.
It is advisable to develop the procedures that will be used in various emergencies before they arise. Items such as a fire, medical emergency, chemical release, or dangerous weather situations (such as tornado watches or warnings) should be included in this evaluation. Some of these may have already been evaluated and plans made, the laboratory staff should be made aware of the appropriate actions as well.
Strong acids such as sulfuric or hydrochloric present safety dangers when in contact with the skin. When making acid solutions, it is important to remember that the acid will react violently with water. To minimize the danger of this reaction, always do as you oughtter, add acid to water.
Sulfuric acid is a strong dehydration agent. It will remove the moisture from organic materials such as cloth and leave only a carbon residue. Put a drop of concentrated sulfuric acid on a paper towel and the reaction will be as if you set the paper on fire. A carbon residue will be all that is left. The same thing will happen to your skin. A large spill of sulfuric acid will be similar to spilling a can of motor oil. The surface will become super slippery. Don’t try to walk through it. You won’t make it.
Hydrochloric acid has the same corrosive properties as sulfuric acid with the added danger that the vapors are very strong and harmful.
Nitric acid is another acid commonly found in wastewater laboratories. It is also corrosive and its vapors are poisonous. Nitric acid and sulfuric acid should not be stored together.
Bases are dangerous to the skin just like acids, but they work in a different manner.
Sodium hydroxide is a strong base. A few drops on the skin will at first cause little concern and feel very slick, much like soap. The resulting burn will be just as painful as that of an acid.
The world is filled with toxic materials and so is the testing laboratory. Recent legislation has resulted in the production of Material Safety Data Sheets (MSDS) on just about any chemical material that is received in the plant. These sheets must be supplied by your chemical supplier and provide information as to the safety hazards and precautions to be applied when using these materials. Material Safety Data Sheets should be carefully read and the warnings and advice followed. A file of these data sheets must be kept in the laboratory for reference.
Mercury is an element commonly found in laboratories that needs to be carefully handled. Also known as quicksilver, mercury is a very dense material usually encountered in liquid form. It is frequently used in barometers, thermometers, and switches. Every effort should be made to obtain equipment that does not contain mercury as it is very toxic and affects the eyes, kidneys, lungs, and mental performance.
Combustible, Flammable, and Explosive Materials
Consult the Material Safety Data Sheets concerning the combustible nature or explosive potential of chemicals used in the laboratory.
The samples tested in a wastewater treatment laboratory contain mostly water so they present little or no danger of being combustible, flammable, or explosive. It is the reagent chemicals used to complete the specific tests that can have a flammable or explosive ingredient.
If flammable material should ignite, stay calm and use good judgement without taking unnecessary chances. If the material can be extinguished using appropriate equipment at hand, then do so. If there is any question that the fire is not completely extinguished, report it to the fire department. Even if you are confident that the fire has been extinguished, it may still be advisable to notify the fire department.
A careful evaluation of the material that is normally stored on site as well as the equipment that is used in the laboratory will determine the most effective suppression or extinguishing material or equipment to be used. There are different sizes of fire extinguishers containing various extinguishing agents.
An added hazard in the wastewater testing laboratory is the presence of pathogens (disease–causing organisms) in most of the samples. The concentration will vary with the sample. Primary sludge will contain many more infectious organisms than secondary effluent.
This is an area where personal hygiene and housekeeping will have a lot to do with prevention of problems.