SECTION V - HANDLING OF CHEMICALS

General 

Know the physical and health hazards associated with the chemicals you are using.  Carefully read the chemical's label and Material Safety Data Sheet (MSDS) before using a chemical for the first time.  Also review the appropriate Standard Operating Procedure.  These documents will provide any special handling information.  After the potential hazards associated with the chemicals and the experimental processes are evaluated you can modify work procedures so that laboratory hazards are minimized or eliminated. 

Keep the following guidelines in mind when handling chemicals: 

  • Do NOT work alone in the laboratory.  If you must work alone, notify someone as to where you will be and when.

  • Use required personal protective equipment.  Eye protection is always appropriate. 

  • Label all containers with chemical content.

  • Keep your hands and face clean.  Wash thoroughly with soap and water after handling any chemical and whenever you leave the lab.

  • Avoid direct contact with any chemical.  Always wear a laboratory coat, at a minimum.

  • Keep chemicals off your hands, face and clothing, including shoes.

  • Never smell, intentionally inhale or taste a chemical.

  • Smoking, drinking, eating and the application of cosmetics is forbidden in areas where hazardous chemicals are used or stored.

  • Always use chemicals with adequate ventilation or in a chemical fume hood.  Refer to the MSDS and the Standard Operating Procedure to determine what type of ventilation is needed.

  • Use hazardous chemicals only as directed and for their intended purpose.

  • Inspect equipment or apparatus for damage before adding a hazardous chemical.  Do not use damaged equipment.

  • Never use mouth suction to fill a pipette.  Use a pipette bulb or other pipette-filling device.

  • Electrically ground containers using approved methods before transferring or dispensing a flammable liquid from a large container.

For specific information regarding chemical handling, contact your supervisor, instructor or OHS. 

Laboratory Fume Hoods 

Local exhaust ventilation is one of the best engineering methods available to reduce the health risk associated with the use of hazardous chemicals in the laboratory.  Laboratory fume hoods[1] are the most common local exhaust ventilation devices found in the laboratory.  Fume hoods are used to prevent hazardous, offensive, or flammable gases and vapors from mixing with the general room air.  A hood, especially with the sash down, also acts as a physical barrier between the laboratory workers and chemical reactions.  The hood can also contain accidental spills of chemicals. 

Check the MSDS, appropriate Standard Operating Procedure, or chemical label for special ventilation requirements, such as: 

  • "Use with adequate ventilation"

  • "Use in a fume hood"

  • "Avoid inhalation of vapors"

  • "Provide local exhaust ventilation" 

Ventilation recommendations must be adapted to the work site and the specific process. 

To be effective, laboratory fume hoods must be installed and used correctly.  The National Research Council in Prudent Practices for Handling Hazardous Chemicals in Laboratories (1981) recommends that the following factors be remembered in the daily use of hoods: 

1.  Hoods should be considered as backup safety devices that can contain and exhaust toxic, offensive, or flammable materials, when the design of an experiment fails.  Hoods should not be used as a means for disposing of chemicals.  Thus, apparatus used in hoods should be fitted with condensers, traps, or scrubbers to contain and collect waste solvents or toxic vapors or dusts. 

2.  Hoods should be evaluated periodically to ensure adequate face velocities (typically 60-100 fpm) and the absence of excessive turbulence.  Further, some continuous monitoring device for adequate hood performance should be present and should be checked before each hood is used.  If inadequate hood performance is suspected, it should be established that the hood is performing adequately before it is used.  To report inoperable hoods, contact Physical Plant or OHS. 

3.  Hoods should be kept closed (vertical sashes down and horizontal sashes closed), except when adjustments of apparatus within the hoods are being made.  Sliding sashes should not be removed from horizontal sliding-sash hoods. 

Keeping the face opening of the hood small improves the overall performance of the hood. 

4.  The airflow pattern, and thus the performance of a hood, depends on such factors as placement of equipment in the hood, room drafts from open doors or windows, persons walking by, or even the presence of the user in front of the hood.  For example, the placement of equipment in the hood can have a dramatic effect on its performance.  Moving an apparatus 5-10 cm back from the front edge into the hood can reduce the vapor concentration at the user's face by 90%. 

5.  Hoods are not intended for storage of chemicals.  Materials stored in them should be kept to a minimum.  Stored chemicals should not block vents or alter airflow patterns. Whenever practical, chemicals should be moved from hoods into cabinets for storage. 

6.  Solid objects and materials (such as paper) should not be permitted to enter the exhaust ducts of hoods as they can lodge in the ducts or fans and adversely affect their operation. 

7.  An emergency plan should always be prepared for the event of ventilation failure (power failure, for example) or other unexpected occurrence such as fire or explosion in the hood. 

8.  Persistent problems with fume hoods should be reported to Physical Plant or OHS. 

Engineering and administrative controls to reduce or eliminate exposures to hazardous chemicals include: 

  • substitution of a less hazardous substance

  • substitution of less hazardous equipment or processes (e.g., safety cans for glass bottles)

  •  isolation of the operator or the process

  •  local and general ventilation (e.g., use of fume hoods)

  •  hazard education

  •  job rotation 

 

PERSONAL PROTECTIVE EQUIPMENT (PPE) 

The MSDS will list the personal protective equipment recommended for use with the chemical.  The MSDS typically addresses "worst case" conditions.  Therefore, not all of the equipment shown may be needed for a specific job.  For example, respirators should be considered only when engineering and administrative controls (such as fume hoods and/or general dilution ventilation) cannot be used or made adequate, or while such controls are being instituted. 

The employer must provide appropriate personal protective equipment to employees, at no cost to the employees.

Eye Protection 

Eye and face protection must be worn whenever its use will reduce or eliminate injury.  It is recommended that eye protection ALWAYS be worn in the laboratory.

The need for adequate eye protection is fundamental to the use of chemicals, including housekeeping materials such as wax strippers, detergent and toilet bowl cleaners, and operations such as grinding, drilling, sawing with power tools.  Eye protection, and at times face protection, is required wherever the potential for eye injury exists.  Areas where eye protection must be worn include (but is not limited to) laboratories, auto repair shops, machine shops, welding areas, most other industrial technology shops, sandblasting operations, concrete cutting or grinding, and chemical handling operations areas. 

Eye protection is required for all personnel and visitors in these areas. These areas shall be posted as such. Personnel may NOT enter such areas where chemicals are being handled or automated processes are in operation without eye protection. 

Ordinary (street) prescription glasses do not provide adequate protection.  (Contrary to popular opinion these glasses cannot pass the rigorous test for industrial safety glasses.)  Adequate safety glasses must meet the requirements of the standard Practice for Occupational and Educational Eye and Face Protection(ANSI Z.87.1 1989) and must be equipped with side shields.  Safety glasses with side shields do not provide adequate protection from splashes.  Therefore, when the potential for a splash hazard exists, other eye protection and/or face protection must be worn (e.g., chemical safety goggles or face shields), as appropriate. 

Splash goggles with splash proof sides or a face shield must be used when protection from a chemical splash is needed. 

Face shields afford protection to the face and neck.  Face shields must be worn if there is an explosion or implosion (pressure or vacuum) hazard and when transferring cryogenic liquids. 

Special eye protection is available for protection against laser, ultraviolet (UV), welding and brazing, or intense light sources. 

Eye protection must be made available to employees and visitors, at no cost to them, when the potential for eye injury exists. 

If you have any questions regarding the selection of appropriate eye and/or face protection, call OHS. 

Use of Respirators 

Respirators are designed to protect only against specific types of substances and in certain concentration ranges, depending on the type of equipment used. 

Respirator selection must be based on the hazard and the protection factor required. 

Types of respiratory protective equipment include:

  •   particle-removing air purifying respirators

  •   gas and vapor-removing air purifying respirators

  •   air supplied respirators

You should familiarize yourself with the limitations of each type of respiratory protective equipment used and the signals for respirator failure (odor breakthrough, filter clogging, etc.). 

Respirators are not to be used except in conjunction with a written respiratory protection program.  Contact OHS for a copy of the college’s written program.  If your work requires the use of a respirator, you must receive special training from qualified personnel.

Protection of Skin and Body 

Skin and body protection require protective clothing and include protection of various parts of the body either completely or partially. 

Eye and face injuries are prevented by the use of the following: 

  • safety glasses with side shields for dust and flying object protection

  • chemical splash goggles for chemical splash, spray and mist protection

  • face and neck shield for head and neck protection (these devices must always be used with safety glasses or goggles). 

Where there is no immediate danger to the skin from contact with a hazardous chemical, but where it is undesirable to have the employee or student expose himself in his street clothes, laboratory coats, coveralls, aprons or protective suits shall be worn.  These garments should not leave the laboratory, except for laundering or disposal. 

Chemical protective clothing in the form of disposable work suits should be provided when there is a high potential for gross contamination.  Special attention must be given to sealing all openings in the clothing.  Tape can be used for this purpose. Caps should be worn to protect hair from contamination. 

Exposures to strong acids and acid gases, organic solvents and strong oxidizing agents, carcinogens, and mutagens require the use of protective equipment that prevents skin contamination.  In these situations, impervious protective equipment must be used.  Examples include: 

  •  rubber or nitrile gloves

  •  rubber boots

  •  rubberized suits

  •  special protective equipment 

Protective garments are not equally effective for every hazardous chemical.  See Table 1, “Chemical Resistance Chart”, for assistance in selecting the appropriate garment. 

Some chemicals will "break through" the garment in a very short time.  Therefore, garment selection is based on the specific chemical used.  Check with your supervisor, or OHS if you are uncertain as to which materials will provide an adequate barrier to chemicals.

 

Table 1

CHEMICAL RESISTANCE CHART

 

Natural

Rubber

NBR Nitrile

Neoprene

PVC

PVC/Nitrile

Acetic Acid

E

G

E

E

E

Acetone

E

P

G

P

F

Ammonium Hydroxide

E

E

E

E

E

Animal Fate

P

E

G

G

E

Alcohols (Most Common)

E

E

E

E

E

Butyl Acetate

P

P

P

E

E

Battery Acid

P

P

P

E

E

Bleach Solutions

F

F

F

E

E

Chromic Acid

E

E

E

E

E

Citric Acid

E

E

E

E

E

Creosote

P

E

G

F

G

Dimethylformamide

E

F

G

P

F

Glycols

E

E

E

E

E

Gasoline

P

E

G

F

G

Hydrochloric Acid (Conc.)

G

E

E

E

E

Hydrochloric Acid (Dil.)

E

E

E

E

E

Hexane

P

E

E

G

E

Kerosene

P

E

G

F

G

Plasticizers

P

G

F

P

F

Methyl Ethyl Ketone

G

P

P

P

F

Methyl Isobutyl Ketone

P

P

P

P

F

Mineral Spirits

P

E

G

P

F

Naphtha

P

E

F

F

G

Nitric Acid (Conc.)

P

E

F

F

G

Nitric Acid (Dil.)

G

E

E

E

E

Phenol/Carbolic Acid

F

P

G

G

G

Phosphoric Acid

G

E

E

E

E

Picric Acid

E

E

E

E

E

Potassium Hydroxide

G

E

G

E

E

Polyester Resin

E

E

E

E

E

Sodium Hydroxide

G

E

G

E

E

Stoddard Solvent

P

E

F

F

G

Sulfuric Acid (Conc.)

P

P

P

E

E

Sulfuric Acid (Dil.)

E

E

G

E

E

THF (Tetrahydrofuran)

P

P

P

P

P

Toluene

P

P

P

P

F

Turpentine

P

E

P

F

G

Urea

E

E

E

E

E

Xylene

P

F

P

P

F

 

Adhesives:

 

 

 

 

 

 

-Epoxy

E

E

E

E

E

 

-Solvent Based

P

G

F

F

G

 

-Water Based

E

E

E

E

E

 

 

 

 

 

 

 

 

Herbicides and

Insecticides:

 

 

 

 

 

 

-Oil Based

P

E

G

E

E

 

-Water Based

E

E

E

E

E

 

 

 

 

 

 

 

 

Oils:

 

 

 

 

 

 

-Animal

P

E

G

G

E

 

-Cutting

P

G

F

G

E

 

-Fuel

P

E

E

G

E

 

-Hydraulic Petroleum

P

E

G

G

E

 

-Hydraulic Ester

P

F

G

G

G

 

-Mineral

P

E

G

E

E

 

-Petroleum

P

E

E

E

E

 

-Silicone

E

E

E

E

E

Key:  E – EXCELLENT  G – GOOD  F – FAIR  P - POOR (NOT RECOMMENDED)

 

Gary Lee
Director of Environmental Health
4601 College Blvd.
Farmington, NM  87401
(505) 566-3063 or (505) 566-3190