Help Us Get the Lead Out  by Ilona Szigethy

Here’s another item to add to your hazardous waste collection - autoclave tape.  That’s right! Autoclave tape is made with a series of angled stripes (/ / / / /) that appear light beige under normal conditions and darken in the autoclave when exposed to sufficiently high heat and pressure. It is commonly used in many hospitals, clinics, and laboratories to indicate that a package of materials, instruments, flasks, glassware etc. has been sterilized.
 
In some brands of tape, the color changing compound in the angled stripes contains lead-a harmful environmental pollutant that affects practically all body systems including the central nervous system, kidneys, and blood cells.  The lead content in some tapes greatly exceed limits for ‘regular’ land fill waste.  After autoclaving the lead’s ‘absorbability’ by the skin greatly increases due to heat-induced change in the chemistry of the lead component.  EH&S is promoting a program to “Get the LEAD Out” by requiring laboratories to purchase lead free autoclave tape and collect and dispose of autoclave tape with lead as hazardous waste.  During EH&S’s upcoming laboratory inspections starting early in 2010, we will be able to offer a roll of lead free tape in exchange for any unused rolls of leaded autoclave tape.  Note: tape that contains the word “Autoclaved” instead of the angled stripes is lead free.  

Some of the most common brands of lead containing autoclave tape (prior to November 2008)  are Propper  “Canada”, Fisherbrand, 3M Comply, and Shamrock.  As an alternative Fisher and VWR now carry “Lead Free” autoclave tape. The best way to determine if your autoclave tape contains lead is always the Material Safety Data Sheet (MSDS).  For future purchases, see the names of some lead-free brands below.

lead tape tape

Sodium Hydride Incident and Response by Kevin McGhee

Sodium Hydride (NaH) is one of many pyrophoric reagents used in laboratory research.  NaH is extremely reactive with water, to the point that the dry powder will often react with moisture in air. Recently a lab worker was weighing a small amount of the dry powder in ambient air when it began to smolder. The reagent was quickly moved to the hood, where it was placed in an inert (nitrogen gas) environment and covered with sand. The lab worker correctly stopped a colleague from using a CO2 extinguisher, which might have dispersed the material and exacerbated the problem.  Quick thinking on the part of the lab staff, as well as their use of available resources from EH&S and experienced faculty, prevented a serious incident from occurring with this pyrophoric material.
As a basic engineering control, pyrophoric solids should only be handled in an inert atmosphere, e.g., in a glove box flushed with inert gas. With sodium hydride specifically, the mineral oil dispersion should be used whenever possible; the dry powder form should only be used in a glove box. Sand should always be kept on hand to use as an extinguishing agent in case of a fire, and lab workers must always wear personal protective equipment when using these materials.

In order to better prepare the university community for such situations, EH&S and the Department of Chemistry co-authored The Safe Use of Pyrophoric Reagents http://www.ehs.columbia.edu/pyrophorics.pdf, which was used as a reference guide by the lab staff in responding to this incident.  To further emphasize the importance of handling pyrophoric reagents with extreme care and to help familiarize lab workers with appropriate techniques and precautions for handling pyrophoric reagents, EH&S invited a speaker from Sigma-Aldrich to give a lecture on the subject on December 7, 2009. Researchers from multiple departments that use these materials were in attendance.

Hydrofluoric Acid Use in Laboratories  by Terrence Jaimungal

Hydrofluoric (HF) acid is one of the most hazardous chemicals used in Columbia laboratories. It reacts corrosively with a wide variety of materials, making it both useful and dangerous. Most metals, natural rubber, rock, concrete, glass, fiberglass, ceramics and glazes are dissolved by HF; however it does not react with metallic lead and platinum, polyethylene, polypropylene, Teflon, plexiglass (acrylic), or wax.

HF users and first responders are at the greatest risk of exposure during incidents involving a release. Gaseous hydrogen fluoride and hydrofluoric acid have nearly the same toxicological properties and can be considered interchangeable.  HF burns are unlike other acid burns, where injury is caused predominately by dissociated H+ ions. HF readily penetrates skin, corroding soft tissue and bone.  Inhaled HF vapor/gas can cause delayed pulmonary edema.  Systemic HF poisoning removes Ca2+ from soft tissues and bones (hypocalcemia).  Ca2+ regulation is critical for normal cell function, neural transmission, bone integrity, blood coagulation and intracellular signaling. Sudden death following acute exposure to large quantities of HF is not uncommon. Exposure to dilute solutions may not cause any pain and therefore may go undetected for hours. 

A delay in first aid/treatment of HF exposure may result in painful, slow-to-heal burns and/or systemic poisoning. Immediate first aid should include removal by flooding exposed areas with copious amounts of water, followed by an application of calcium gluconate first aid gel, which must be on hand wherever HF is used. 

HF must be used only in a certified chemical fume hood; procedures involving even small quantities of dilute solutions must not be performed on an open lab bench. Use the buddy system-never use HF when alone in the lab. Prevent contamination by using plastic trays or bench paper on work surfaces before starting HF procedures. Ensure calcium gluconate first aid gel is on hand and check the expiration date.  

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