Topic: Outdoor Structures

Date Posted: Thursday, October 29, 2015
Posted by: Tanya Zanfa (Master Admin)

Q & A: How safe is the treated wood at your home?

Q & A: How safe is the treated wood at your home?


PETOSKEY — Around Northern Michigan, public playground closures have drawn attention to one wood-treating agent and the arsenic-exposure concerns it involves.

But playground features aren’t the only outdoor structures built with wood that contains this agent. Around many homes, there are decks, landscaping features and numerous other outdoor items with lumber that used chromated copper arsenate (CCA) as a preservative.

Manufacturers phased out CCA use for treating residential lumber more than a decade ago. The decisions came amid health and environmental groups’ concerns about the lumber’s potential to leach arsenic — a carcinogen to humans. But many older structures built with such wood still stand around homes.

Health and consumer-protection groups usually stop short of directing homeowners to remove all CCA-containing lumber from their properties. But numerous sources do suggest some precautions for limiting potential arsenic exposure around this wood.

The following are questions that CCA-treated wood may raise for consumers, along with answers.

What is arsenic?

Arsenic is a naturally occurring element. It can be found in rocks, water and soil, as well as in living organisms such as plants and animals. Compounds containing arsenic have been used in numerous manufacturing applications, and some levels of it can be found in a variety of foods and beverages. Although arsenic is considered poisonous and carcinogenic to humans, experts believe it’s impossible to totally eliminate a person’s exposure to it.

What health issues can arsenic present?

The U.S. Centers for Disease Control and Prevention notes that unusually large doses of inorganic arsenic can cause a variety of ailments, ranging from nausea, vomiting, and diarrhea to dehydration and shock. Long-term exposure to high levels of inorganic arsenic in drinking water has been linked to skin disorders and increased risks for diabetes, high blood pressure, and several types of cancer.

What is chromated copper arsenate?

Chromated copper arsenate (CCA) is a wood preservative containing copper, which serves as a fungicide; arsenic, which acts as an insecticide; and chromium, a chemical fixing agent which binds the ingredients to wood. According to the U.S. Environmental Protection Agency, the substance has been used in pressure-treating lumber since the 1940s. By the 1970s, CCA-treated wood was in use for a majority of outdoor structures in residential settings, intended to guard against rotting caused by insects and microbial agents. By the end of 2003, manufacturers voluntarily phased out certain CCA use for lumber to be used around homes and children’s play areas. At that time, EPA policy began prohibiting use of CCA to treat residential lumber, with few exceptions.

Health concerns surrounding CCA tend to involve its leaching from the wood treated with it. The EPA notes that the amount and rate of leaching varies and is dependent on factors such as climate, rain/soil acidity and wood age.

What concerns have arisen locally about this type of wood?

As in many communities elsewhere, concerns about arsenic exposure have prompted closures of some Northern Michigan playgrounds with CCA-treated lumber structures, including one at Harbor Springs’ Shay Elementary School and another at Boyne City’s Veterans Park. Elevated arsenic readings on the ground nearby were among the findings prompting these decisions. Harbor Springs Public Schools tore down equipment built with that wood and replaced it, while Boyne City officials are looking into measures that could limit potential arsenic exposure while salvaging their popular community playground.

If you spend time around CCA-treated structures, how significant are the health risks?

Health Department of Northwest Michigan medical director Dr. Josh Meyerson, who has a background in pediatrics, said routine activities around CCA-treated outdoor structures likely won’t increase health risks by large amounts.

“The reality is, we haven’t really seen in the routine day-to-day use of these structures that they have a problem,” he said.

But Meyerson added that steps to limit exposure around the yard or playground can be sensible. He noted that the most significant bodily exposure to arsenic tends to occur through the mouth, a part of the body that young children’s hands often come in contact with. And since elementary-age youngsters often use playgrounds repeatedly over multiple years, he said it’s understandable for officials to use abundant caution when elevated arsenic levels are found in those areas.

If you have older treated-lumber structures around the yard, what precautions are in order?

Different sources recommend a variety of approaches for controlling arsenic exposure.

The EPA and some other federal agencies don’t call for outright removal of CCA-treated wooden structures, but do offer a mix of precautions to follow for contact with the lumber and nearby surfaces.

Some of these were noted in a brochure published by the EPA, U.S. Consumer Product Safety Commission and U.S. Department of Agriculture. Recommendations include:

— Work outdoors and wear protection (e.g., goggles, gloves, and dust mask) when sawing, cleaning, or handling CCA-treated wood.

— Thoroughly wash hands and all exposed body parts with soap and water after handling or playing on CCA-treated products.

— Launder clothing worn when handling CCA-treated wood separately.

— Children should not eat while on CCA-treated playgrounds, as arsenic may be transferred to the mouth.

— Do not allow children or pets to play in soil or other material under or near CCA-treated decks or structures.

— CCA-treated wood should not be used where routine contact with food or animal feed can occur, including areas used to plant vegetables, fruits, herbs, etc. If you have a garden vegetable planter constructed with CCA-treated wood, install a plastic liner before filling the planter with soil to reduce exposure to CCA.

— Do not use CCA-treated wood for mulch, cutting boards, counter tops, bee hives, compost, structures, or containers for storing human food or animal feed.

— Never use treated wood in areas where it may come into direct or indirect contact with drinking water.

Along with hand-washing, the health department’s Meyerson suggested another step for children after spending time around a treated-lumber play structure — removing shoes when they enter the house in order to avoid spreading CCA residue indoors.

Like some others in the public health and environmental fields, Meyerson typically doesn’t see it as necessary for families to remove CCA-treated play structures if they have them in their own yard, provided that care is taken around playtime.

“I feel if they take reasonable precautions, it’s fairly safe for them to keep that structure if it’s (in sound shape),” Meyerson said.

On the other hand, Meyerson said the case for removing the wooden play equipment would be stronger if it’s showing structural decay, splintering or other problems that can come with age.

Can leaching of CCA from wood be controlled?

The EPA/CPSC/USDA brochure notes that regularly applying an oil- or water-based penetrating coating (such as a stain or sealant) to CCA-treated wood structures may reduce potential exposure to chemical residues.

Various researchers have found that these types of coatings can limit the rate at which CCA is released from wood, but their effectiveness varies with the type used and environmental conditions affecting the wood.

The Center for Environmental Health is one organization that does suggest replacement as the safest approach for dealing with CCA-treated structures. But if removal isn’t feasible, this nonprofit suggests applying a solid or semi-transparent, oil-based deck stain in an effort to control arsenic releases. Its suggested approach is to apply the treatment at least once a year, to use two coats on the first application and to visually check the stain’s condition every six months for signs of wear.

Boyne City’s case is one in which crews did apply sealant to playground structures every two years — as recommended by the manufacturer — but recent test results still showed elevated arsenic levels in the woodchips lining the ground nearby as well as in core samples of the wood itself. With 12 inches or more of wood chips lining the ground around the structure, one theory is that if the chip layer prevented crews from sealing the lower-most portions of the structure, it could be that the preservative is leaching into the wood chips and soil at those locations.

How should you dispose of CCA-treated wood?

Experts recommend against burning this type of wood. Meyerson notes that this approach can create ash with concentrated arsenic levels. As an alternative, federal agencies suggest landfill disposal — but urge consumers to check first to see if a given waste site accepts this type of debris.

What are some alternatives to wood treated with CCA?

Following the phaseout of CCA for many residential uses, the USDA Forest Products Laboratory notes that interest strengthened in several arsenic-free alternatives. These lumber treatment options, such as alkaline copper quaternary (ACQ) and copper azole, often use copper as their primary biocide.

While these other preservatives are less toxic than CCA, some experts note that their higher concentrations of copper can increase corrosion of certain metal fasteners and hardware.

Borate-based wood preservatives offer protection against damage by insects and fungi, as well as low toxicity to mammals. But their suitability for outdoor use may be limited, given their tendency to leach from wood in wet environments.

When working with woods that use these treatments or disposing of them, some suggest taking protective steps similar to what one would use with CCA-treated lumber.

Along with treated lumber, other materials possibilities for outdoor structures include naturally resistant woods such as redwood and cedar, as well as plastic-wood composite lumber.

What about arsenic testing in your own yard?

Meyerson noted that various commercial providers offer soil testing options for homeowners, but added that these services can be pricey. Since some presence of arsenic is to be expected around older treated lumber structures, he suggested focusing instead on the safety measures when spending time around it.

However, if homeowners are looking to plant a vegetable garden on a newly bought property — and have reason to believe that CCA-treated lumber previously was in the area — Meyerson said soil testing would be sensible under those circumstances, since arsenic has a tendency to concentrate in some garden produce.

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