How Wood Can Make You Sick and How To Stay Safe
As you sit on your wood outdoor deck while eating food you prepared using a wood cutting board and your children play on equipment made with wood beams, does it ever cross your mind that the wood could make you or your family sick? Here are some things you should know about some wood products and how to stay safe.
Is the wood in your life safe?
You and your family probably come into contact with wood and wood products in a variety of ways every day, so I have chosen a few of the more common ones that could have an impact on your health. Let’s start with wood cutting boards.
Cutting boards can be a vehicle for bacteria involved in food poisoning, which is why it is critical that you clean any cutting boards you use for food preparation to avoid cross contamination. For example, if you have used a board to cut raw meat or fish, you should use another board to cut vegetables.
In other words, one cutting board is not enough. But should those cutting boards be wood or plastic?
According to the University of Tennessee, if you think the answer is “plastic” because wood is porous and thus more difficult to get and keep clean, research does not necessarily support your guess. For example, the University noted that one study concluded that plastic and wood cutting boards are about equal when it comes to food safety.
If you want to use a wood cutting board that meets the requirements of the Food and Drug Administration’s (FDA) Food Code for restaurants and other food-handling facilities, then you should get one that is made of “hard maple or an equivalently hard, close-grained wood,” and the same goes for “cutting blocks, bakers tables, and utensils such as rolling pins, doughnut dowels, salad bowls, and chopsticks.”
Regardless of what your cutting boards are made of (and there are glass and stainless steel as well), you should always use a different one for raw animal-based foods and a different one for produce and similar items. You should also wash and dry your cutting boards after every use.
A recent study in Food Microbiology reported on the spread of bacteria that can cause food poisoning (Salmonella enteritidis) on different cutting boards (wood, plastic, stainless steel, glass). The authors wanted to see how many bacteria would spread from contaminated chicken skin to tomatoes after the boards were exposed to four different processes: no cleaning, rinsed in running water, cleaned with dish soap and physical scrubbing, and use of dish soap, scrubbing, and disinfected with hypochlorite.
The bacteria were detectable on all the cutting boards and on the tomatoes when the first three procedures were tested, but not for the last one. Thus the authors concluded that “hypochlorite as a disinfecting agent helped to reduce cross-contamination.”
Treated wood at home
If you have an outdoor wooden deck, fence, borders around your garden or yard, or playground equipment, then there is a chance the wood in those products may present a health issue. Here’s why.
Wood is a natural product and vulnerable to decay, so wood targeted for outdoor structures are typically treated with chemicals to prevent deterioration. That treatment falls into two main categories:
- Water-based treatments of chromated copper arsenate (CCA) and ammonium copper quat (ACQ). The former contains arsenic, which has been associated with lung and skin cancer in people who have experienced long exposure. ACQ is a newer process and is less toxic. Wood treated with CCA is typically used for home and garden projects, such as playground equipment, decks, patios, and fences.
- Oil-based treatments, which include creosote and pentachlorophenol (PCP). These processes are used on wood destined to be railroad ties and utility poles. However, sometimes individuals use these treated wood items for decks, tables, and play equipment, and they are not recommended for these purposes.
The Wisconsin Department of Health Services notes that the CCA can wash out of treated wood and contaminate the soil, and that people may get the chemicals on their hands when touching the wood. To reduce the chance of exposure, especially for children, the US Consumer Product Safety Commission recommends that playground equipment be sealed or painted with an oil-based sealer every two years.
Fortunately, if you are planning new construction of a deck or other outdoor wood projects, the EPA reports that treated wood containing CCA is no longer being made for use in most residential situations. If, however, you have a deck made of treated wood or otherwise have such wood in your possession, here are a few safety tips:
- Do not use wood treated with creosote or PCP for home or garden projects
- Never use treated wood for any indoor home construction projects
- If you have a deck made of CCA-treated wood, seal it with an oil-based sealer every two years
- Never use treated wood for any projects in which food may come in contact with the item, such as picnic tables, cutting boards, or countertops
- Do not let children play under decks made with treated wood. Pets who sleep or stay under such decks may transport arsenic into the house
- Do not burn treated wood, because the smoke will contain toxic substances
- Anyone who makes contact with treated wood should wash their hands
- If you plan to cut or sand treated wood, wear a dust mask and collect the saw dust in a drop cloth. Dispose of the cloth after you complete the job and wash your hands and clothing thoroughly.
Another type of treated wood that is popular is wooden pallets. Many people like to use these items to make a variety of creative projects, and the fact that they are often free (companies frequently dispose of pallets outside their buildings, free for the taking) makes them especially appealing.
However, pallets used in international shipping are required by the US Department of Agriculture to be treated with heat or methyl bromide, which is a toxic pesticide. Although use of this chemical has been restricted in recent years because of health concerns, some pallets with this toxin are still around.
To tell whether a pallet has been treated with methyl bromide or heat, look for the IPPC (international plant protection convention) stamp on the wood. Pallets marked “HT” were treated with heat and are not contaminated with chemicals, while those with “MB” have methyl bromide.
Wood pallets also may have been exposed to agricultural chemicals or bacteria if they were used to store or transport produce. Therefore, if you can determine how the pallets were used, you can take steps to use them safely by cleaning, sealing, or painting them, or using them in ways that do not expose anyone to potential hazards.
The bottom line
Wood is a precious natural resource and a substance used for many everyday products. To help ensure the health of you and your family, you should be aware of how to use wood products in a safe manner.
Environmental Protection Agency
Soares VM et al. Transfer of Salmonella enteritidis to four types of surfaces after cleaning procedures and cross-contamination to tomatoes. Food Microbiology 2012 Jun; 30(2): 453-56
University of Tennessee
Wisconsin Department of Health Services