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Preserving, Anyone?

Formaldehyde is one of the nastiest chemicals around

Vince McLeod, CIH

Vince McLeod is an American Board of Industrial Hygiene-certified industrial hygienist and the senior industrial hygienist with Ascend Environmental + Health Hygiene LLC in Winter Garden, Florida. He has more...

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From tissue fixation to benchtop perfusions to instrument sterilization to preserving everything from cell cultures to whole animal specimens, formaldehyde is one of the most commonly used chemicals in research laboratories. It is typically used in a 37 percent aqueous solution known as formalin that is sometimes mixed with other chemicals. But improper or careless use can cause a plethora of problems. In this article we will take a closer look at the hazards of formaldehyde and how to safely use this common sterilizer and preservative.

What’s the worry?

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Plenty! To be blunt, formaldehyde is one of the nastiest chemicals around. For starters, we will examine its physical and chemical properties and the health effects.1 Formaldehyde is a flammable, colorless gas with a pungent, suffocating odor. The vapor is just slightly heavier than air. It is classed as both a powerful irritant and a sensitizer. It is intensely irritating to mucous membranes, and its presence is easily felt even in very low concentrations. Published studies have shown the odor threshold is well below one part per million (ppm).2,3 The eyes, nose and throat are first to feel the tingling and then irritation. High concentrations, above five ppm, are not tolerated by most individuals. You can experience severe tearing in the eyes as well as coughing and irritation of the upper respiratory tract.

What most people fail to note is that formaldehyde is also a sensitizer. This means that the irritating effects, especially from low-level concentrations, which are so easily felt upon initial exposure, will gradually subside with continued exposure as the senses become fatigued and the chemical’s numbing effect takes over. We have met many employees not wanting to be labeled complainers that tell us they just “tough it out” for a few minutes and the feeling goes away. They just do not understand that they are still being exposed.

Formaldehyde is also a skin irritant and may cause dermatitis and possible allergic reactions from repeated exposures due to skin sensitization. Vapors or solutions may cause pain, white discoloration, roughness and burns. In exposed individuals, subsequent exposures may result in a sensitization dermatitis characterized by the sudden eruption of blisters on the eyelids, face, neck, scrotum and arms. Prolonged or repeated exposures may cause burns, numbness, itching rash, fingernail damage, hardening or tanning of the skin, and sensitization. Absorption through the skin also adds to the total exposure.

What’s the harm?

Potentially serious health effects can result from formaldehyde exposures. In addition to the mucous membrane and skin effects, which are largely reversible upon one’s removal from the exposure, formaldehyde can cause biological effects. These range from central nervous system depression to kidney and liver damage, reproductive and fetal effects, and cancer. Repeated or prolonged low-level exposure may cause headache, rhinitis, nausea, drowsiness, respiratory impairment, kidney injury and pulmonary sensitization. Neuropsychological effects may include sleep disorders, irritability, altered sense of balance, memory deficits, loss of concentration and mood alterations. Menstrual disorders and secondary sterility have occurred in women.

Formaldehyde is listed by EPA, NIOSH, OSHA and others as a suspect human carcinogen.1,3 EPA considers formaldehyde a probable human carcinogen (cancer-causing agent) and has ranked it in its Group B1. Long-term exposure may increase risk of upper respiratory tract cancers, including those of the nasal cavity and sinuses.

What should you do?

First and foremost, you need to determine where and how formaldehyde is used in your facility. Inspect all those areas while activities are ongoing. Note any odors. Interview employees on their procedures. Note the type of formaldehyde products used. Using this information, take time to evaluate the exposure hazards you may have.

As is our custom, the Safety Guys turn to the OSHA formaldehyde standard, 29CFR1910.1048, for regulatory requirements and guidance.4 This standard covers all occupational exposures to formaldehyde, including gas, solutions and any materials that release formaldehyde.

The first step is to determine employee exposures by conducting appropriate monitoring. If in-house capability is not available, a competent industrial hygienist or similar professional can handle the job. OSHA has established an action level of 0.5 ppm and a permissible exposure limit (PEL) of 0.75 ppm, both based on eighthour time weighted averages (TWA). There is also a short-term exposure limit (STEL) of 2.0 ppm, a 15-minute average that employees should never exceed. Periodic monitoring should be conducted every six months for employees exposed at or above the action level.

Following the monitoring, employees potentially exposed above the limits should enter a medical surveillance program. An initial medical history is documented by use of a questionnaire and a baseline physical is conducted. OSHA provides considerable guidance in the rule appendices and on its website.

Safety and health training is essential for all employees falling under this standard. Training should focus on the signs and symptoms of exposure, the possible health effects of exposure, proper personal protective equipment, medical surveillance, monitoring, exposure controls and first aid.

Prevention is key

The essential exposure control is properly designed and adequately maintained engineering systems, i.e. ventilation. We have experienced problems with facility spaces changing uses over time. Turn around, and suddenly you have anatomy labs in what was office space before. Or surgeries performed out on the bench top without any exhaust. Review ventilation in all formaldehyde use areas. Ensure adequate exhaust and proper design. Ideally, you should capture vapors as close to the source as possible though use of snorkel exhaust or fume hoods. Provide sufficient room air changes, dilution and mixing. Most important, make sure formaldehyde use areas are on dedicated single-pass ventilation systems. Recirculation systems are not recommended for these areas.

Protecting our employees and providing a safe workplace is our number one goal. Formaldehyde is ubiquitous and essential to successful research in many applications. It is potentially hazardous and, used carelessly, can produce serious harm. But with careful planning and well-thought-out procedures combined with the right personal protective equipment and exposure controls, we can use formaldehyde safely and protect employees.

Safety Tip

Forbid Smoking, Eating and Drinking in the Laboratory
By James A. Kaufman

The practice of forbidding smoking, eating, and drinking in laboratories is one of the basic good hygiene practices. Unfortunately, it is often one of the most frequently disregarded. Too many people seem to have a “good reason” for continuing these bad habits. None of these reasons are good enough.

These practices protect people in laboratories from ingesting toxic chemicals or infectious materials. The stuff that’s on your hands ends up in your mouth.

I’ve watched science department heads drink coffee while supervising the lab. I’ve seen teachers make stir-fried vegetables in a wok in the lab between classes for lunch. Don’t do it. Set a good example yourself and enforce the rules.

Set up a separate area that can be used for taking breaks, making coffee, and consuming food. Don’t allow it in the lab. And that includes applying cosmetics, too.

It’s not only a bad practice but it is also against the law. Two OSHA regulations speak specifically to this unfortunately widespread practice. One is the bloodborne pathogens standard, 29CFR1910.1030. The other is the sanitation standard, 29CFR1910.141(g)2/4.

There are many worthwhile experiments that involve eating something. For example, teaching colligative properties by making ice cream. Take your students to the cafeteria, use paper plates and plastic utensils and teach your students about safe practices at the same time. Remember, safety is a teachable moment.

Also remember, Pierce College in Tacoma, Washington was sued for 2.5 million dollars following the death of a young woman. She drank a saline solution as part of an A&P class. It contained sodium azide as a preservative. She died four days later.

Many laboratories have ice machines. They should be clearly labeled: “This Ice Is Not for Human Consumption”.

Source: Kaufman, James A., Laboratory Safety Guidelines - Expanded Edition, The Laboratory Safety Institute,

Vince McLeod is an American Board of Industrial Hygiene– certified industrial hygienist and the senior industrial hygienist in the University of Florida’s Environmental Health and Safety Division. He has 22 years of occupational health and safety experience at the University of Florida, and he specializes in conducting exposure assessments and health-hazard evaluations for the university’s 2,200-plus research laboratories.


  1. Formaldehyde. Material Safety Data Sheet. Mallinckrodt- Baker, Inc. Phillipsburg, NJ. September 2009.
  2. Medical Management Guidelines for Formaldehyde. Agency for Toxic Substances and Disease Registry. Atlanta, GA. September 2010. http://www.atsdr.cdc. gov/mmg/mmg.asp?id=216&tid=39
  3. Formaldehyde. U.S. Environmental Protection Agency, air toxics website. Washington, D.C. November 2007.
  4. Formaldehyde. Occupational Safety & Health Administration. Washington, D.C. December 2008. document?p_id=10075&p_table=STANDARDS