By Peter Wallace
Thousands of everyday products are made with formaldehyde-based adhesives, including numerous materials and products common to the wood products and building construction industry. Recent trends toward “green” construction and new products marketed as “formaldehyde-free” or “no added formaldehyde” have raised concerns that composite wood panel and other building products containing residual formaldehyde may pose health risks. This article is intended to provide basic information about formaldehyde, its applications and regulatory measures that already are in place to ensure the safe use of products made with formaldehyde-based resins.
What Is Formaldehyde?
Formaldehyde is one of the simplest biological forms of carbon, made of a single atom of carbon with two attached hydrogen and one oxygen atom attached (HCHO). Formaldehyde also is one of the most abundant organic compounds in the universe. In outer space, formaldehyde is made mainly from carbon dioxide. Measurements of the amount of methyl formate — a product of alcohol and formaldehyde — in the swirling dust clouds that dot the Milky Way galaxy suggest that if the gaseous methyl formate condensed into liquid form, a typical dust cloud would contain a thousand, trillion, trillion gallons of the chemical.
Formaldehyde is a component of all living things, from bacteria and plants to animals and humans, and occurs naturally in the air we breathe. Formaldehyde is naturally present in the human body with concentrations of approximately one to two parts per million (ppm) in blood, and it is exhaled in human breath. It does not accumulate in the environment. In our bodies, formaldehyde is formed and metabolized continually so that it does not accumulate. Similarly in the atmosphere, formaldehyde breaks down in sunlight to form carbon dioxide and water.
Formaldehyde’s chemistry makes it an extremely versatile contributor to the production of thousands of items used every day. In fact, studies show that sales of formaldehyde and formaldehyde-containing goods account for more than 1.2 percent of the yearly Gross Domestic Product (GDP) of the United States and Canada – more than $145 billion.1
About half of all formaldehyde is used to make composite wood panels, engineered wood and other building products. The remainder serves as an essential component in making other consumer goods, including vaccines, photographic film, paper products, cosmetics and personal care products. While little or no formaldehyde may remain in the finished items, most of these products could not be made without it and still retain the attributes that make them useful.
Formaldehyde and Wood
All types of wood — and therefore all wood products — naturally contain and emit low but detectable amounts of formaldehyde. In fact, the formaldehyde present in wood is what helps hold it together in the first place.
Long ago, scientists capitalized on formaldehyde’s natural properties to create thermoset resins that have been the prominent and cost-effective binder in the wood and construction industries. Formaldehyde’s reactive nature makes it highly efficient and useful in resin formulations; it cross-links with other ingredients to form a strong bond. Formaldehyde is used to make three principal types of binding resins:
Formaldehyde-Based Resins are Proven Performers that You Can Use Safely with Confidence
By Betsy Natz
Thousands of everyday products are made with formaldehyde-based adhesives, including a multitude of materials and products common to the wood products industry. Plywood, composite wood panels, insulation, cabinetry and flooring, engineered lumber, furniture, roofing materials and many others are manufactured with formaldehyde resins that provide strength, function and appearance advantages to the finished products.
From an economic standpoint, formaldehyde-based resins are cost-effective, particularly when compared to more expensive and untested alternatives. Formaldehyde Council Inc. stands strong with its members in defending products made with formaldehyde-based resins based on a long history of safe, proven performance and continuing efforts to ensure that low-formaldehyde-emission products are available in the marketplace.
Numerous government agencies in the United States have guidelines and regulations in place to manage the production, storage, handling and use of formaldehyde. The safety of their products, their communities and their employees is foremost in our members’ business operations. Because of regulations and the combined efforts of science and the industries that make and use formaldehyde, the levels emitted into indoor air from wood products that contain formaldehyde have decreased dramatically over the past 30 years and now approach normal ambient background levels.
Based on what we know today about formaldehyde toxicity, consumers and workers are protected when formaldehyde is handled and used properly and following government regulations. (More information about formaldehyde and health may be found in the paper “Formaldehyde and Human Health,” available from FCI’s Web site, www.formaldehyde.org.)
With the discovery in 1979 that formaldehyde caused nasal cancer in laboratory rats following lifetime exposure to very high levels, an extensive effort was undertaken – and continues – to understand better the potential effects in humans. Current data does not support the correlation of these findings to cancer in humans.
The FCI is spearheading a research program to further supplement the scientific understanding concerning this versatile chemical. The results of this research, in combination with findings from the U.S. Environmental Protection Agency’s ongoing carcinogenicity evaluation of formaldehyde under its Integrated Risk Information System program, should further clarify the level of understanding regarding the safety of formaldehyde for consumers and formaldehyde industry workers so they can continue to make wise choices and derive the vast benefits of this simple, widely used chemical.
Betsy M. Natz is founding executive director of The Formaldehyde Council, Inc. (FCI). The Formaldehyde Council, Inc. (FCI) is the science and advocacy center for the
formaldehyde industry. FCI and the formaldehyde industry are committed to the safe and responsible use and benefits of formaldehyde and products made from it, and to ensuring formaldehyde’s accurate scientific evaluation. For more information, visit www.formaldehyde.org. Reach Natz at (703) 741-5752 or bnatz@formaldehyde.org. |
1. Urea-formaldehyde (UF) resins’ largest use is in binders or adhesives for wood products composites, including particleboard, medium-density fiberboard, hardwood plywood and fiberglass mat used to make roof shingles.
2. Phenol-formaldehyde (PF) resins are used as wood adhesives for oriented strandboard (OSB) and plywood and for insulation, laminates, foundry materials and molding compounds.
3. Melamine-formaldehyde (MF) laminates are used almost entirely for decorative applications including cabinets, furniture, paneling, flooring and ceiling tile in the wood products industry, and also have numerous non-construction uses, including automotive applications, coil coatings, dinnerware, tire cord, and treating paper and textiles.
Formaldehyde Exposure
Formaldehyde has been measured in both indoor and outdoor air, with concentrations typically higher in indoor air. Outdoor levels in urban and rural areas in the United States range from one to 68 parts per billion (ppb) in air or 0.001 to 0.068 ppm. Indoor air concentrations are dependent on the type of building construction and air-exchange rates, with average levels today in conventional homes of 14 ppb and in office buildings of 13 ppb. It has been estimated that 10 to 25 percent of exposures might result from environmental tobacco smoke.
Because of government oversight and voluntary product emissions standards, coupled with the combined efforts of science and the various industries that manufacture and use formaldehyde, the levels emitted into indoor air from products that contain formaldehyde have decreased dramatically over the past 30 years and now approach normal ambient background levels. Humans are highly sensitive detectors of formaldehyde down to levels of approximately 500 ppb (0.5 ppm). At higher levels (1,000 ppb [1 ppm]), a dose-response relationship is evident and the presence of formaldehyde begins to cause mild eye, nose and throat irritation. At 3,000 ppb (3 ppm) and higher, there is immediate acute discomfort, with tearing of the eyes, nasal discharge and significant discomfort.
Against this background, it is not surprising that formaldehyde is one of the most researched chemicals, with literally hundreds of studies on metabolism, toxicity and effects in animals and humans. Government oversight and regulation of formaldehyde is extensive to protect human health and the environment. These standards help ensure the responsible use, production, storage and handling of the chemical.
In the United States, the Occupational Safety and Health Administration sets standards to protect workers, and the Environmental Protection Agency, Food and Drug Administration, Department of Housing and Urban Development, Consumer Product Safety Commission and others ensure consumer protection.
Formaldehyde Controversy
If formaldehyde is found in all living things and naturally in the ambient air, then why is there any controversy over this chemical at all? In order to understand the issues, it is helpful to understand two basic, regulatory science concepts: hazard and risk.
Hazard refers to the inherent capability of a substance to cause an adverse effect at some dose level, no matter how high. For all chemicals, the critical aspect of the science of toxicology is the concept of the dose-response (i.e., the larger amount of chemical exposure, the greater the response). In studying the cancer-causing potential of chemicals, doses far in excess of what would be typical exposures are used in order to increase the probability of finding an effect. Risk is the statistical probability that exposure to a substance, at a given level, will cause an adverse effect (toxicity).
In the 1970s, scientists at CIIT Centers for Health Research (formerly the Chemical Industry Institute of Toxicology) found, in a dose-response study with rats and mice exposed at various levels, that formaldehyde caused nasal cancer in rats following lifetime exposure in the extreme highest levels in the study. These levels were many times in excess of human detection and the point of severe irritation and reaction.
In the same testing, the animals exposed to lower levels had no nasal cancers. Since then, in order to understand the potential for effects in humans at low doses, extensive scientific research has been conducted on formaldehyde by industry, world government health agencies and academia.
In 2004, the International Agency for Research on Cancer (IARC), which is part of the World Health Organization, concluded that formaldehyde is “carcinogenic to humans (Group 1),” on the basis of “sufficient evidence in humans and sufficient evidence in experimental animals.” It is important to understand that IARC judges the scientific evidence based exclusively on the hazard posed by a particular chemical and not the risk. In other words, exposure and dose play no role in an IARC evaluation.
Meanwhile, the EPA, which classifies formaldehyde as a “probable human carcinogen,” is waiting for results from a debated National Cancer Institute (NCI) worker study update before proceeding with its own review of formaldehyde’s potential carcinogenicity under its Integrated Risk Information System (IRIS) program. Essentially, the EPA’s current “probable” classification means that scientific studies have provided sufficient evidence of animal carcinogenicity, but limited evidence of human cancer-causing potential. Once the NCI study update is completed, the EPA’s cancer evaluation (IRIS review) will resume, proceeding toward a formaldehyde classification update by late 2008.
The question here is if a chemical or substance is a hazard at a very high exposure level, is it a risk to humans at environmentally relevant exposures?
As shown in Figure 1, the evolution of predicted cancer risks associated with exposure to 0.1 ppm formaldehyde for six hours per day, five days per week has decreased dramatically as the scientific basis for using animal data to predict potential risks to humans has improved.
Because of the newest detailed studies of how formaldehyde affects animal nasal tissue, it is now possible to construct a biologically based model to describe these effects. Biologically based modeling (Clonal Growth Modeling) greatly minimizes the uncertainties inherent in currently used regulatory approaches for carcinogens, i.e., the “no-threshold model,” which assumes that cancer risk is linear to zero.
The Clonal Growth Model developed by the CIIT for formaldehyde predicts accurately how high the dose level of formaldehyde must be to produce tumors in animals over a lifetime exposure. From this, it is possible to estimate the concentration necessary to increase the human cancer risk above the one-in-a-million level.2 Based on this model, it would take a lifetime exposure (80 years) to formaldehyde in excess of 600 ppb to cause a one-in-a-million extra risk of nasal cancer in humans.
Moreover, a recent National Academy of Sciences (NAS) report notes that irritation of the eyes and upper respiratory tract is the primary human health effect of concern for setting exposure limits for both short- and long-term inhalation exposures to formaldehyde. “Risk of cancer and other chronic health effects appears to be negligible at concentrations that do not produce chronic irritation and overt target tissue damage.”3
Current regulatory exposure levels are designed to prevent the known sensory irritant and odor properties of formaldehyde. These effects are key considerations in the risk assessment of formaldehyde. Because formaldehyde is so irritating to the nasal passages, humans simply cannot tolerate, even for a few minutes, exposure to formaldehyde at levels that have been tested and shown to produce tumors in animals.
Conclusion
Formaldehyde is a key chemical building block in providing us with many of the products we rely on for everyday products. High levels of formaldehyde, like many other chemicals, are hazardous and should be handled and treated accordingly.
However, formaldehyde is also a naturally occurring chemical and an essential step in our metabolism. It is not possible to eliminate all formaldehyde from our outdoor or indoor environments as long as we breathe and exhale. Therefore, it is essential for science, industry and regulators to work together to determine safe, practical levels of ambient formaldehyde and then design products to work within these guidelines.
Clearly, formaldehyde’s myriad uses bring quality and value to composite panel and engineered wood products. And just as clear is the fact that public policy measures are extensive to ensure the safety and health of workers in the formaldehyde and wood products industries and consumers who benefit from the thousands of wood products made with formaldehyde. The formaldehyde industry is committed to continue to provide the wood products industry with resin systems they can use safely and with full confidence.
Peter D. Wallace is business manager, nonwoven resins, for Hexion Specialty Chemicals Inc., Columbus, OH, and is a member of the Formaldehyde Council Inc.'s Product Stewardship Committee. Wallace is a graduate of New York State College of Environmental Science and Forestry at Syracuse University and has more than 35 years experience in the wood products, nonwoven and resin industry. Hexion is the largest U.S. manufacturer of formaldehyde and adhesives based on formaldehyde chemistry. Reach Wallace at (828) 584-3800, ext. 117, or peter.wallace@hexion.com.
Additional Source
“Formaldehyde: Overview of Current Issues and Challenges For the Future.” Robert Golden, Ph.D., International Nonwovens Technical Conference, 2005.
References
1“The Economic Benefits of Formaldehyde to the United States and Canadian Economies.” Global Insight, August 2005.
2 Human respiratory tract cancer risks of inhaled formaldehyde: dose-response predictions derived from biologically motivated computational modeling of a combined rodent and human dataset. Connolly, R.B., Kimball, J.S., Janszen,D., Schlosser, P.M., Kalisak,D., Preston,J. and Miller,F.J., Toxicol Sci.82(1):279-96, 2004.
3 “Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants.” National Academy of Sciences, 2004.�