The toxicity of materials is assessed by their Lethal Dose 50% (LD50) or Lethal Concentration 50% (LC50). LD50 is defined as the dose at which 50 percent of the exposed test animals (generally, rats or mice) died, usually within 1-2 hours after being dosed by ingestion, injection or skin exposure. LC50 is defined as the concentration in air at which 50 percent of the test animals (generally rats or mice) died, usually within a specified time after being exposed by inhalation.

A substance is considered extremely toxic if it has an LD50 of less than 5 mgs/kg of animal body weight. To humans, this is the equivalent of a taste (less than 7 drops). It is Highly toxic if it has an LD50 of between 5 and 50 mg/kg of animal body weight to a human, this would be about a teaspoon.

[collapsed title=Lab Requirements]

Georgia Tech requires that all labs be kept locked however, there are additional security measures that owners of extremely toxic chemicals must implement to ensure that the chemicals’ location is always known and that only persons who have the PI’s permission may have access to them. This means that extremely toxic chemicals:

• Must be stored in a locked cabinet or drawer in the lab
• Must have a sign out sheet document the following information
  • who uses them,
  • how much they used and
  • when they used  it

Additionally, organo-mercury compounds, which have an LD50 ­ in the 5-50 mg/kg range (highly toxic) must also be kept locked up and treated like the extremely toxic group.  This is because many of these materials are absorbed through the skin and have no immediate symptoms.  In 1997 a researcher at Dartmouth College died as a result of a miniscule skin exposure to dimethyl mercury (http://en.wikipedia.org/wiki/Karen_Wetterhahn)   In 2010, a cache of “lost and forgotten” dimethyl mercury containers were found in a GT lab during a lab clean out by students who had no idea as to what they were handling:  It is extremely important that we never “lose track” of these chemicals, hence the requirement to treat them as “extremely toxic”.

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[collapsed title=Before Purchase or Work]

Before you purchase or start working with any substance read the SDS. If the material is highly or extremely toxic, or if you are unsure about its level of toxicity, call EH&S for a Hazard Assessment

EHS will:

• Review the toxicological data for the material with which you intend to work.
• Inspect your work area.
• Review your Standard Operating Procedure for working with highly and extremely toxic compounds.
• Review the training records of all persons in the lab. 
• Test engineering controls as appropriate. 
• Test safety equipment as appropriate.
• Provide recommendations for PPE appropriate for the particular material with which you are working.
• Determine if medical surveillance of affected employees is needed.

Before purchasing a highly or extremely toxic material, please read the guidelines for handling these materials:

• Highly and Extremely Toxic Materials
• Mercury and Mercury Compounds

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[collapsed title=Hydrofluoric Acid]

Hydrofluoric acid (HF) is not just a corrosive, it is a potentially deadly poison with latent effects that may not manifest for up to 24 hours after the exposure, depending on the concentration of the acid and the duration of exposure. 

HF readily penetrates the skin, causing deep tissue layer destruction. Severity and rapidity of onset of signs and symptoms depends on the concentration, duration of exposure, and penetrability of the exposed tissue. Pain may be delayed.

CONCENTRATIONS LESS THAN 20% - Erythema and pain may be delayed up to 24 hours, often not reported until tissue damage is extreme. In one study, 7% HF produced symptoms in 1 to several hours, 12% HF in less than one hour, and 14.5% HF immediately.

CONCENTRATIONS 20 TO 50% - Erythema and pain may be delayed from 1 to 8 hours, and is often not reported until tissue damage is extreme.

CONCENTRATIONS GREATER THAN 50% - Produces immediate burning, erythema, and tissue damage.

Systemic fluoride toxicity may result from ingestion, inhalation, or extensive dermal burns. Hypocalcemia, hypomagnesemia, hyperkalemia (potassium), pulmonary edema, metabolic acidosis, ventricular arrhythmias, and death are possible.

Eye exposure may result in severe ocular damage with concentrations greater than 0.5%. Fume exposure commonly causes eye irritation and can also cause ocular injury. Signs and symptoms may be delayed.

Ingestion may result in vomiting and abdominal pain; painful necrotic lesions, hemorrhagic gastritis, and pancreatitis have been reported after significant exposure.

Inhalation of hydrofluoric acid vapors may cause severe throat irritation, cough, dyspnea, cyanosis, lung injury and pulmonary edema resulting in death.

HF should always be handled in a fume hood.  PPE should include a long-sleeved acid resistant apron and a face shield in addition to the usual lab coat and safety glasses.    

Gloves must be chosen to be resistant to  HF but also be compatible with the process:  Heavy 6 mil nitrile, butyl or neoprene gloves worn over nitrile examination gloves are preferred, but may inhibit manual dexterity to a point of interfering with the work and endangering the laboratorian.  In this case, double gloving with nitrile examination gloves is recommended while keeping alert to any wetness on the outer glove- in which case the outer glove should be changed immediately.

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[collapsed title=Dangerous Powders]

“Dangerous Powders” include antineoplastics, nano materials, and other chemicals that are simply poisons. The #1 concern in working with these materials is exposure to the aerosolized powder, so the first step in avoiding this hazard to buy it directly from your supplier in suspension.  If this is not possible, the next step is to dissolve or suspend the powder in a liquid as early in your process as possible.  Dangerous powders should be weighed in a balance enclosure.  Balance enclosures can be simple:

PICTURE - PLEXIGLASS BOX WITH LID AND HAND HOLES

Plexiglass box with lid and hand holes

PICTURE - GLOVE BOX WITH VENTING CAPABILITY

Glove box with venting capability

Or more elegant:

PICTURE - BALANCE ENCLOSURES

Balance enclosures do not necessarily have to be ventilated but remember to always wet wipe the outside of the container, the balance and the inside of the enclosure when you are done, whether or not you think you spilled anything.

[collapsed title=Cleaning up a Dangerous Powder]

• Do not do anything that might aerosolize the powder
• ​Seal the receiving container before you take it out of the enclosure, glove box or fume hood.
• If possible, dissolve or suspend the material in liquid before taking it out of the enclosure, glove box or fume hood
• Do not broom, dry sweep or vacuum (no, not even with the ones that say HEPA)
• Clean up spill from the outer edge toward the center, not side to side:
  • Cover the spill with wet paper towels
  • Using the paper towels, scoop the material into a PLASTIC dust pan (or just pick it up with two hands)
  • Repeat using additional wet paper towels until the material is all gone
  • Wet wipe surface (from outer edge to center)
  • Bag and label the waste
• Use EHSA to generate a waste card (ehsa.gatech.edu) and request a pick up

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[collapsed title=Antineoplastic Agents]

Antineoplastic agents are covered under restricted purchases. (See the Section on Restricted Purchases).  The complete program can be found at In Vivo Agents.

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[collapsed title=Nano Materials]

 Here are the GT Guidelines for working with nanomaterials.

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[collapsed title=Carcinogens]

Carcinogens are substances which are capable of causing cancer. Cancer, simply put, is the uncontrolled growth of cells that can occur in any organ. Carcinogenic chemicals come in all forms: solid, liquid, and gaseous.  A big difference between carcinogens and many other chemicals is that there is not necessarily a dose- response relationship between exposure and the development of cancer.  Therefore, all effort must be taken to avoid exposure to carcinogens.  Also, cancer has latent effects, often not manifesting for 10 to 30 years after the exposure. 

Protection from carcinogens in the lab is no different than working with other dangerous substances: hygiene; engineering controls such as fume hoods, biosafety cabinets, and glove boxes; personal protective equipment such as gloves, safety glasses, and lab coats; proper procedures; and training.  Carcinogens are treated with the same level of caution as extremely toxic materials, starting with increased fume hood speeds from an average of 100 lfm to 120 lfm.  If you are working with a carcinogen, please contact EHS to conduct a safety review of your process and to have your fume hood speed increased from the normal 100 linear feet/minute to 120 linear feet/minute.

[collapsed title=OSHA Regulated Carcinogens]

The Occupational Safety and Health Administration (OSHA) regulates 26 recognized carcinogens:

• 1,2-dibromo-3-chloropropane
• 1,3-Butadiene
• 2-Acetylaminofluorene
• 3,3'-Dichlorobenzidine (and its salts)
• 4-Aminodiphenyl
• 4-Dimethylaminoazobenzene
• 4-Nitrobiphenyl
• Acrylonitrile
• alpha-Naphthylamine
• asbestos
• Benzene
• Benzidine
• beta-Naphthylamine
• beta-Propiolactone
• bis-Chloromethyl ether
• Cadmium
• Coke oven emissions
• Ethylene oxide
• Ethyleneimine
• Formaldehyde
• Inorganic arsenic
• Methyl chloromethyl ether
• Methylene Chloride
• Methylenedianiline
• N-Nitrosodimethylamine
• Vinyl chloride

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[collapsed title=Carcinogen Hazard Levels]

OSHA adopted the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) in April of 2012. This system recognizes 3 hazard levels for carcinogens:

Category 1 - Known of Presumed Carcinogen

Subcategory 1A - Known Human Carcinogen based on human evidence

Subcategory 1B - Presumed Human Carcinogen based on demonstrated animal carcinogenicity

Category 2 - Suspected Carcinogen - Limited evidence of human or animal carcinogenicity

Other organizations such as the International Agency for Research on Cancer (IARC) and the American Conference of Governmental Industrial Hygienists (ACGIH) also have classification systems for carcinogens.  All of these systems are based on the availability of human data, giving those chemicals with more human data, the higher (more dangerous) rating.[/collapse]

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Work Practices for Handling Carcinogens will vary, depending on whether it is a solid, a liquid, or a gas.

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