Safety topics

Here you will find pages on a number of laboratory safety topics concerning laboratory operations at Earlham College.


If you have any questions about chemical hygiene and safety, we encourage you to contact our chemical hygiene officer.


Dangers from phosgene formation

Chloroform, though dangerous on its own due to toxicity and carcinogenicity concerns, can form dangerous phosgene over time.

Phosgene (COCl2) is a toxic gas/liquid used as a chemical warfare agent during WWI. Phosgene can form in chloroform as it is exposed to oxygen and amounts of UV light (although UV light is not always necessary if catalytic contaminants are present). Phosgene has a characteristic odor of cut hay.

Phosgene is very toxic, with fatality occurring with short exposures of 50ppm and exposures of less than one minute at the 500ppm level. Persons exposed to phosgene may feel no adverse effects immediately, but may later suffer from pulmonary edema (build-up of fluid in the lungs) and possibly death up to 24 hours later.

What should be done to protect users of chloroform?

Due to dangers from phosgene as well as the inherent dangers from chloroform itself, chloroform bottles should always be opened and dispensed in the hood. Persons using chloroform should also utilize gloves and eye protection at all times. If any cut-hay or similar smell is detected when using chloroform or any other chlorinated solvent, the incident should be reported and the individuals involved should seek medical attention.

How do I know if my chloroform bottle contains phosgene?

Every bottle of chloroform should be treated as if it contains phosgene to help prevent exposure, however, testing is possible using test strips or sampling tubes. Testing can be done by the Chemical Hygiene Officer or can be done by the user using strips prepared as stated:

Strips of filter paper are dipped in 5% w/v Diphenylamine and 5% w/v Dimethylaminobenzaldehyde in an alcoholic solution (ethanol works fine) and then allowed to dry. Strips should be a very light yellow when dry, and activate to a dark yellow/orange color upon presence of phosgene.

Phosgene contaminated chloroform should not be used, and should be segregated and marked for waste disposal.

Material Safety Data Sheet (MSDS)

Each department on campus is required to maintain a MSDS collection of chemicals they currently use/store. However, for general use, online viewing of MSDS sheets may be more practical. Below is a list of websites with MSDS databases and a description. If no MSDS is found using these sites, a Google search may also work.

Vermont SIRI (,000General Chemicals
Sigma-Aldrich90,000General Chemicals
Fisher Scientific61,000General Chemicals
Crop Data Management Systems4200Pesticides


Use and disposal

Needles used in laboratories are a significant liability and threat to safety. These needles may have hazardous substances on/in them such as toxic chemicals or bio-hazardous substances such as viruses or bacteria. Use of needles should be limited due to the safety concerns associated with the ease at which a needle could poke the skin and distribute hazardous substances directly into the bloodstream.

Needles, once uncapped, should NEVER be recapped as this in the most common cause of needle sticks.

Needles and used syringes should be disposed of, as a unit, in an appropriate, labeled waste container. These waste containers should be puncture resistant and located near needle usage areas and are available commercially. If bio-hazardous materials were used with any needles in a waste container, that waste container must be autoclaved prior to landfill disposal.

At no time should any needle, razor blade or similarly sharp item be placed in any Glass Disposal boxes. The plastic bag/cardboard combination in those containers is easily penetrated by needles and can pose a serious hazard to workers.

If a needle stick should occur, appropriate first aid should be administered based on the suspected substance that needle was in contact with. If this information is unknown, it should be treated as serious and appropriate action taken to ensure the victims health.

All needle sticks must be reported to the chemical hygiene officer, no matter how minor or severe.

Next steps

We continue to monitor the effects of an industrial fire 1.1 miles from campus.
We continue to monitor the effects of an industrial fire 1.1 miles from campus.