Is there formaldehyde in the glue of bamboo cutting boards? Is it dangerous?

Question

Many purveyors of bamboo cutting boards make a point to advertise that the cutting board is made from formaldehyde-free glues.

There seems to be fairly widespread advise to avoid formaldehyde in bamboo cutting boards, such as from the following two examples:

From The Kitchn:

When shopping for a bamboo board, look for ones that use formaldehyde-free glues, such as those from Totally Bamboo or Bambu.

From Pure Health Guide:

Shopping tips: Look for a bamboo cutting boards made with food-grade glue (formaldehyde free)

Is there any credible evidence that there is practical danger from formaldehyde containing glues in bamboo cutting boards? Are they on the market, and are the levels of formaldehyde sufficiently high as to cause dangerous doses of this chemical to migrate into food prepared on the cutting board?

Note: this question is prompted by a question asked over on Seasoned Advice.

Answer 1

In American Woodworker Sep-Oct 1993 there is an article A Guide to Glues by Curtis Johnson "biochemist at Oregon State University". In the article he says:

...urea-formaldehyde glues, are my personal favorite for cabinet making. Their high water resistance makes them good for jobs like tabletops, cutting boards or laminated countertops.

In urea-formaldehyde glue there is initially formaldehyde, which is intended to polymerize. However, as explained in the linked Wikipedia article, even the polymerized material can release some formaldehyde.

There is a searchable FDA list of Indirect Additives used in Food Contact Substances

Examples of polymers derived from formaldehyde are:

UREA-FORMALDEHYDE RESIN, METHYLATED

MELAMINE-FORMALDEHYDE

POLY(FORMALDEHYDE-CO-GUANIDINE-CO-UREA)

So the FDA considers some polymers of formaldehyde safe enough to be added to items such as cutting boards that contact food.

Answer 2

Evidence:

1. Formaldehyde is an industrial chemical used to make other chemicals and products including chewing gums.

U.S. Consumer Product Safety Commission (CPSC): Formaldehyde can be released into the air (off-gas) from materials and products made with it. Formaldehyde can also be released into the air by automobiles, cigarettes, and burning wood, kerosene or natural gas. It is also a naturally occurring substance.

Formaldehyde is also used as a feed additive with no attributed health risk for the end consumer.

European Food Safety Authority (EFSA): Formaldehyde is currently used as a feed additive and as a preservative for skimmed milk intended for pigs. In their risk assessment, EFSA’s experts concluded that while there is no health risk for consumers exposed to this substance through the food chain, its inhalation may cause cancer. Appropriate measures should be taken to reduce worker exposure to feed containing formaldehyde.

2. Formaldehyde exposure at higher levels can affect people differently and cancer risk for long term exposure is termed as "limited" referring to US Environmental Protection Agency.

Toxics Use Reduction Institute: Exposure to formaldehyde can cause irritation and dermatitis and has been found to cause nasopharyngeal cancer in some occupational groups, including embalmers who use formaldehyde to preserve the deceased. Because formaldehyde is highly reactive, water soluble and readily metabolized by almost all human cells, overexposures tend to do damage at the point of contact, most commonly the eyes and the upper respiratory tract.

3. Humans are naturally exposed in the environment to formaldehyde present in air, food and water. Exposure to formaldehyde in drinking water at 10 mg for 1 day is not harmful for human health.

Agency for Toxic Substances and Disease Registry: The US EPA has determined that exposure to formaldehyde in drinking water at concentrations of 10 milligrams/liter (mg/L) for 1 day or 5 mg/L for 10 days is not expected to cause any adverse effects in children. The US EPA has also determined that a lifetime exposure to 1 mg/L of formaldehyde in drinking water is not expected to cause any adverse health effects.

Meaning

1. TL;DR: Extensive research shows that naturally occurring level of formaldehyde in humans is 0.8 to 8.0 parts per billion and the levels of formaldehyde to which most people are exposed in the normal world are not high enough to be toxic. However, more research is needed to confirm whether formaldehyde in cutting boards can migrate into food and cause toxic effects on human health.

American Chemistry Council: While the extremely low level of formaldehyde in human breath is not a realistic health or environmental threat, at exposure levels between 120 ppb and 1,020 ppb, formaldehyde is known to irritate eyes, noses and throats and cause respiratory lesions. Thus, to prevent sensory irritation in the general population, WHO recommends an air indoor quality guideline value for formaldehyde of 81 ppb (averaged over 30 minutes), which prevents both short-term and long-term health effects, including cancer.

Formaldehyde is extensively regulated, and mandatory government standards have been established to enable the safe production, storage, handling and use of this important building block chemical. Additionally, industry has voluntarily adopted product emission standards and developed low-emitting resins, contributing to a significant decline of indoor formaldehyde emissions in recent years.

The amount of formaldehyde through oral intake for consumers from food of animal origin was estimated to be 4 mg per person per day by the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP).

European Food Safety Authority (EFSA): Such levels of formaldehyde resulting from the consumption of milk or meat from animals fed with formaldehyde-supplemented feed would represent 0.1-0.3 % of human oral exposure from background levels in food products and would be below 0.001 % considering the endogenous formaldehyde turnover. Such levels were considered negligible.

2. It is also known that there are several glues in the market containing FDA approved ingredients (polymers of formaldehyde for indirect food contact) which is of use in manufacture of household chopping boards.

Agency for Toxic Substances and Disease Registry: Formaldehyde is found in small amounts in many consumer products including antiseptics, medicines, dish-washing liquids, fabric softeners, shoe-care agents, carpet cleaners, glues, adhesives, and lacquers. If you or a member of your family uses these products, providing fresh outdoor air when you use them, this will reduce your exposure to formaldehyde. Some cosmetics, such as nail hardeners, have very high levels of formaldehyde. If you do not use these products in a small room, or if you have plenty of ventilation when you use them, you will reduce your exposure to formaldehyde. If your children are not in the room when you use these products, you will also reduce their exposure to formaldehyde.

These are different from the “ultra low-emitting formaldehyde resin” category and “no-added formaldehyde resin” category of resins used for manufacturing of wood products.

The Formaldehyde Standards for Composite Wood Products Act of 2010 defines the categories of resins used in the manufacturing of composite wood products. The “ultra low-emitting formaldehyde resin” category includes melamine-urea formaldehyde, phenol-formaldehyde, and resorcinol-formaldehyde resins. The “no-added formaldehyde resin” category includes soy, polyvinyl acetate, and methylene diisocyanate (pMDI) resins.

3. Plastic cutting boards are noted to be easier to clean while wooden cutting boards are also equally safe. Bamboo cutting boards are more resistant to bacteria compared to other varieties of wood.

Bamboo cutting boards are harder and less porous than hardwoods. Bamboo absorbs very little moisture and resists scarring from knives, so they are more resistant to bacteria than other woods.