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Is pressure treat lumber toxic?

Jeff_Anderton's picture

Engineering has required that we frame (2x4 bearing walls and doubled 2x12 floor joists sheeted with doubled 3/4 P.T ply) a room underneath a double garage using all pressure treated lumber. We have never used P.T. in this type of application nor in this quantity. This afternoon we set 10 sticks of 2x12 joist material into the hole that is to be the room under the garage and were overwhelmed with the ammonia type odor off gased from just 10 of 60 of these joists and that was in an open hole. What is this stuff going to smell like upon completion? Will this material off gas in perpetuity? Just what are we smelling? Has anybody ever framed with P.T?
Please let me hear your comments ASAP, and yes we live and work in an area where the engineers rule!! Thanks- Worried Sun Valley, Idaho, Builder

(post #169496, reply #3 of 24)


Have fun with the PT. :-( The stuff is toxic. Treat it as such. Could it be ammonicial cupreous arsenate (however they spell it)?

A local chap was using it to build a dock at a lakefront home. Two week project and it gave him a very nice dose of arsenic poisoning. Might want to review the symptons, just in case. Does the supplier furnish a material data sheet?

When I have to work with it, I wear a Racal filtered air supply helmet, longsleeve clothing and exam gloves. (I'd love the HEPA filter version, but the filter/motor unit alone is $500). The scrap and sawdust is bagged up for disposal.

You sure don't want to be breathing the dust from the saw. (Probably have been, eh?) Got it all over the job site? Bummer.


(post #169496, reply #14 of 24)

The lumber used and presenting quite a problem has finally been identified has ACZA treated. All parties involved from the engineer to the wholesale supplier had assumed that the lumber was CCA treated but due to it's ordered lenght of 24' doug. fir was used thereby necessitating a treatment using the chemical ACZA. Now the industry is telling us that the horrid ammonia odor will dissipate within two to three weeks but the clients have so far resisted our proceeding. I can't disagree when them since I would not use this stuff as framing lumber in my own home. Please direct the remarks to your use of ACZA treated wood.- Thanks- Sorry for being tardy in responding to all your great replies to my quiry but I spend most of my time building or lately attempting to pacify concerned clients.

(post #169496, reply #15 of 24)


You ought to try the Racal.

Since I wear glasses, the standard dust mask or respirator just fogs my glasses, which are then coated with a sawdust sludge.

The hat blows cool(er) air down over the glasses behind the face shield so I can see what I am doing. It's a personal filtered air supply and cooling fan. Got the idea from a woodworker.

I usually use it for spray painting or grinding - even in the summer heat. Come with me to the boat yard in the August heat while I grind bottom paint. I'll furnish the grinders. You can wear a dust mask and shorts. I'll use the helmet, Tyvek coveralls, hood and gloves.


(post #169496, reply #19 of 24)

I have built and installed Permanent Wood Foundations and have never had a problem with smell nor have I ever heard of a "poor chap" getting arsenic poisoning from working with P.T. I would say use common sense, wear a dust mask, goggles, and gloves. Ask your lumber supplier how recently the lumber you have was treated. Good Luck.

(post #169496, reply #20 of 24)

I have worked with pressure treated lumber and for a long time I wondered about the chemicals used to treat it. I figured they were relatively harmless until I saw a show on HGTV where the featured product was pt lumber. According to this source, long term and frequent exposure to pt lumber could be harmful, but what is even more harmful is burning it. They interviewed a couple who owned a cattle ranch. The couple lost 100 cows because the cows grazed on grass in an area where a large amount of pt lumber had been burned. when the grass grew back it contained high amounts of the toxic chemicals used in pt lumber. Unfortunately, where I live people are not really into enviromentally safe products, they are into whatever Bob down the street used on his deck and whatever can be bought at a low price and installed quickly. So, basically, you cant get 'safe' limber without a big hassle and expense. I dont necessarily agree with that, I'm just saying that's how it is where I live.

(post #169496, reply #21 of 24)

A couple of years ago, Organic Gardening ran a series of
articles and editorials concerning treated lumber.They cited
a few reports from independant research labs that stated
that p.t.lumber left arsenic and chromium residue in the
ground adjacent to it.I'll try to find the articles for more
Although O.G.wouldn't be considered unbiased, these
articles give plenty of food for thought.
(The articles were written in response to concerns over
the building of childrens playgrounds with treated lumber.

(post #169496, reply #23 of 24)

It sounds like a good idea to stack PT and let it dry out before using it, But every time I let it sit around the job site it bent and twisted in ways I never belived lumber could!

(post #169496, reply #24 of 24)

Engineering has required that we frame (2x4 bearing walls and doubled 2x12 floor joists sheeted with doubled 3/4 P.T ply) a room underneath a double garage using all pressure treated lumber. We have never used P.T. in this type of application nor in this quantity. This afternoon we set 10 sticks of 2x12 joist material into the hole that is to be the room under the garage and were overwhelmed with the ammonia type odor off gased from just 10 of 60 of these joists and that was in an open hole. What is this stuff going to smell like upon completion? Will this material off gas in perpetuity? Just what are we smelling? Has anybody ever framed with P.T?
Please let me hear your comments ASAP, and yes we live and work in an area where the engineers rule!! Thanks- Worried Sun Valley, Idaho, Builder

(post #169496, reply #1 of 24)

I am not a fan of the most commonly available type of pressure treated lumber, however I have not had a problem with out-gassing and have not seen that mentioned as a problem in the discussions of it.

Most available pressure treated lumber contains compounds of copper and arsenic, both of which can be considered toxic. However, once the surface residue is cleaned off, the remaining arsenic and copper compounds are tightly bound to the wood, as a result, the wood treatment industry has been given an exemption that allows the intact wood to not be considered a toxic waste and to be disposed of as regular waste (there is some controversy about this, particularly when wood scraps are sent to an incinceration plant where the arsenic is liberated and released as fumes.)

The problem is that the pressure treated lumber will eventually deteriorate and in the process release the arsenic. At this point it should then be considered toxic waste. Burning pressure treated wood will also release the arsenic. There is a report somewhere on the web that indicates that as little as one tablespoon of ash from pressure treated wood can kill a full sized cow.

There is a type of pressure treated wood that does not contain arsenic or copper and is advertised as being environmentally safe. There is a lot of discussion on various environmentally oriented web sites and there was a thread on Breaktime about a year ago that discussed this more fully and gave some sites with more information. It should still be available if you search for it.

A couple of links:

(post #169496, reply #2 of 24)

I've never heard of off-gassing from CCA (chromated copper arsenate I think) treated wood. Now both creosote and other oil borne treatments off-gas horrendously. I think there is no way that you have creosote products on your job. I can't remember much about the other oil borne treatments that are more commonly found along highways and wooden bridges then homes. Occasionally a white precipitate of CCA will form on the outside of treated lumber. This precipitate is highly toxic and much more easily absorbed than the toxins that are "bound up in the lumber". Please trust your intuition and your adverse reaction. If something seems wrong it probably is not right. Don't trust what product reps tell you about the toxicity of their products. Think how many Asbestos reps must have reassurred the thousands of workers harmed by their products. Good luck.


(post #169496, reply #4 of 24)

Although the $2.5 billion a year industry insists CCA-treated pt is safe, they concede that the ash is deadly. Lots of this stuff gets incinerated every year. There are allegations that it may leach into soil; the industry denies this. The industry rep. is the AWPI. They do advise -- and perhaps this is just at the whiny EPA's insistence -- these precautions: "After working with the wood, and before eating, drinking, and use of tobacco products, wash exposed areas thoroughly. If preservatives or sawdust accumulate on clothes, launder before reuse. Wash work clothes separately from other household clothing." They also recommend wearing a dust mask/goggles when cutting and collecting all sawdust on a tarp for disposal.

Ironically it sounds like you are suffering from a CCA alternative, ACQ, which in some formulations contains a lot of ammonia that can off-gas to produce the odor you identify as ... ammonia (ACQ = Ammoniacal Copper Quat). Trust your nose and contact the manufacturer right away. At a minimum, given the astonishing amount of pt you're using, the stench could cause someone to pass out and injure themselves. It should be quite an aromatic garage, perhaps even intolerably, for a long time.

Yet another alternative, one I've used recently, is Kodiak, treated with CDDC. (The long chemical names for these compounds are even worse!) Easy to work with, brown-colored, and more expensive. A nice detail, esp. for framing, is that it is kiln dried after treatment, so it arrives reasonably dry.

I'll be interested in seeing how this comes out. Certainly the stuff seems fine if used with caution.

(post #169496, reply #5 of 24)

CCA lumber does leach into the ground. I have read a couple of articles with foot notes to scientific papers reporting this. It definitely is a no no for use in vegetable beds.

(post #169496, reply #6 of 24)

But the AWPI insists otherwise! Emphatically! If we can't trust lobbyists, who can we trust?

(post #169496, reply #7 of 24)


Rich Beckman

(post #169496, reply #8 of 24)

I ran into a lot of people who "know" all about pressure treated wood, and its toxicity. Problem I found, like here on these replies, is that no two people had the same info. Seems like everybody thought they were an expert.

I am by no means an expert on this subject. I did, however, spend two years finding out as much as I could about the effects of pressure treated wood on the environment, people, animals, and wildlife. I am printing the results of two years worth of research, as well as who tested what, what agencies got involved, and what they all concluded. This is simply information for you to read. How you use this information is entirely up to you.

I have found over the last two years of researching that most "informed" people haven't got a clue about the products or services that they are pretending to know so much about. I'm like Andrew, if you can't trust an industry "expert", then who can you trust? I say get all the info you can, then make an informed, educated decision.

Here goes the info:

'b How Safe Is Preservative Treated Lumber?

Modern treated wood products are being used extensively in home foundation construction, decking, retaining walls, picnic tables, playground structures, and is even
being used in high moisture areas such as shower walls (prior to mud an lathe beds for tile).

Pressure treated wood is colored a light green which fades to a weathered gray color over time. It is also available in light brown color.

Pressure treated wood is virtually maintenance free, and requires no additional finishing, unless the wood is to be left in the open air, sunlight, or exposed to extensive
rain. In these cases, it is advisable to apply a water repellent, which will keep the lumber more stable. There is no need to paint or stain the wood unless you want to change the color of the dried wood. If applying a stain, or paint, it is advisable to wait until the wood is completely dry, and has started to turn a grayish color.

Treatment preservatives used are stable, water soluble, salt based chemicals, which in numerous tests conducted over decades, have shown remarkable resistance to wood rotting fungi, and damage by insects. Accelerated laboratory tests have indicated that the wood is basically “petrified”, and has a lifetime of about 100 years.

Treated wood products used in the construction of foundations are required to have more preservative than treated wood used for above ground applications (.60 versus .40). Some of the older wood preservatives used (these are no longer used in the treatment of wood) such as pentachlorophenol, or penta, are toxic, and you should avoid physical contact with these products, or the breathing of their vapors. Creosote, another long time
preservative (still in use) is commonly used for treating heavy timbers, utility poles, pilings, and railroad ties. Creosote treated products should not be used inside the interior of a home.

To improve the penetration and retention of the preservative chemical, the lumber is run through a machine that makes special knife like incisions in the lumber, parallel to the grain. These cuts were very visible in the older treated wood products, but modern manufacturing techniques have allowed the cuts to be almost invisible on today’s treated lumber.

Modern preservative chemicals are dissolved in water and are forced into the lumber and plywood under some 125 to 175 psi, in special treatment chambers. This is not a
simple spraying on, or dipping process. Once the preservative chemicals have been forced deep into the lumber and plywood, a vacuum is applied to draw off excess chemical. The pressure treating process permanently locks the preservative chemicals into the cellular
structure of the wood. The chemicals actually bond with the cellulose of the wood, a process known as “fixation”. This eliminates the food source upon which wood destroying
organisms thrive.

After the treatment process, the lumber and plywood are dried to a low moisture content, providing a clean, dry, odor free product (although most of the mills of today are not drying the lumber as required). Treated wood and plywood retain all of the stiffness, strength, and workability they had prior to the treatment process.

The chemicals used in the process are registered with the Federal Government, and are harmless to humans, animals, and plants. Leaching of the chemicals from the treated products is so minute that elaborate laboratory testing has difficulty detecting the amounts
involved. In addition, it has been found that homes built on permanent wood foundations (treated lumber) have no more arsenic in the air than home built on conventional
foundations. CCA pressure treated wood has been used for decades for grape stakes, tomato stakes, mushroom trays, and planters with no known adverse affects. It is used in
parks, gardens, wildlife sanctuaries, and in some of the most fragile habitats on earth.

A study by R.D. Arsenault (a prominent government researcher during the 70’s and 80’s) showed that if a person was to deliberately rub a wet hand over an entire square foot of freshly treated wood, the amount of arsenic picked up would be less than 1/3 of the arsenic consumed in the average daily diet.

Studies by the Pacific Health Research Institute, Battelle Columbus Laboratories, and Tabershaw Associates on treatment plant workers - the ones who have the highest
exposure to these preservative chemicals - shows no increased health risk from handling these preservatives.

After exhaustive testing, the Texas County Extension Agency, Texas A & M University, the Texas Forestry Service, and the Southwest Research Institute, have all concluded that CCA treated wood products are not harmful to gardens, wildlife, plants, or people.

The California State Department of Health Services, and the U.S. Consumer Products Safety Commission concluded that risks from skin contact with properly processed CCA
treated wood products was negligible.

Testing of Seawalls in Chesapeake Bay showed that water samples taken adjacent to CCA treated wood seawalls met human drinking water standards. Research by Springhorn
Laboratories prove that CCA treated pilings do not harm marine life.

Extensive research at the University of Alabama, and the University of California at Davis concluded that handling CCA treated wood causes no increase in health risks. Laboratory tests have consistently shown that CCA treated wood is no more acutely toxic to humans or other mammals than ordinary table salt.

Based on these studies, as well as extensive studies of their own, the Environmental Protection Agency refused to list the preservatives used in treated lumber, or the lumber itself as toxic. This is what they had to say...

“Arsenic pressure treated wood does not pose undue risk when used for all weather structures, foundations, interior applications to homes and businesses, or garden
applications. Handling of arsenically treated wood is free from hazard attributable to the preservative. A study showed there is no apparent health hazard to the consumer via vaporization, leaching, or other mechanism”.

To ensure that treated wood products perform satisfactorily, standards for wood preservation have been developed over a long period of time. These standards are based on years of performance records of the preservative chemicals, research results, and extensive treating experience.

The American Wood Preservers Bureau AWPB-FDN Standard has developed a series of wood preserving standards and specifications which will ensure end users that the
specified material is properly, and adequately treated.

Each piece of lumber or plywood must bear the quality mark of an approved inspection agency, certified to inspect preservative treated wood. Lumber products must be treated
to a minimum of .25 lbs/cu. ft (above ground use), to .40 lbs/cu. ft (ground contact use), to .60 lbs/cu. ft. (plywood and water contact use), to 1.25 lbs/cu. ft (for marine applications). This standard only applies to CCA (Chromated Copper Arsenate), ACA (Ammoniacal Copper Arsenate), or ACZA (Ammoniacal Copper Zinc Arsenate). It also requires the drying of the wood product to a 19% moisture content, or less. Unfortunately, any end user can see that the drying process is not being done adequately. I
personally have found treated wood so wet that it is actually dripping.

The modern preservatives used contain arsenic in its pentavalent form, the same form of arsenates that are found naturally in water, food, and the human body. In this form, the preservative chemical is not toxic at all. In fact, arsenic is the 12th most common element found in the human body. Any excess of arsenic does not build up in the system, rather it is excreted.

Scientific evidence clearly shows that preservative treated wood does not introduce poisonous arsenic into the family home, and that the chemicals used are environmentally

Handling of CCA treated wood, and CUTTING CCA treated wood are different. When cutting CCA treated wood, the bond of the chemicals to the wood fibers (Fixation) is broken. This allows the concentrated chemicals to become airborne. Although this is a small amount, care should be taken when cutting, or burning CCA treated wood. Standard safety practices when cutting CCA treated wood are fine (use dust mask, sweep up sawdust, etc...). Do not burn scraps of CCA treated wood. When burned, the fibers also loose their bond with the chemicals. These chemicals, when superheated, become mildly toxic. Although it takes a great deal of heat to release these chemicals, they can be released. Avoid the smoke, and the ashes. Once the fibers have burned away, the chemical is still left. Not enough studies have been done on the effects to the human body of these chemicals while burning. Because of the lack of studies, it is recommended that you NOT burn CCA treated wood.

The following sources were also used for information. These sources are all legitimate Federal, State, or Academic research organizations. Also included is the professional organizations that have put their stamp of approval on preservative treated wood products for use by the general public.

American Plywood Association (APA)
National Forest Products Association (NFPA)
American National Safety Institute (ANSI)
The Canadian Standards Institute
Technical Services Department, Council of Forest Industries (British Columbia)

James DuHamel

(post #169496, reply #9 of 24)

On the issue of PT lumber for garden beds I defer to
b Organic Gardening Magazine.
For many years now they have emphatically told their readers that PT will leach toxins into the soil and the toxins will be absorbed by the plants and the consumers of the plants.


(post #169496, reply #10 of 24)

No, I hear there's honor among thieves. :)

(post #169496, reply #11 of 24)

Well, as I said above the CCA pt appears to be safe if handled properly. You raise exactly the point that has concerned me -- what about cutting it? Obviously blades develop a lot of frictional heat which in isolated spots probably ranges pretty high. The blade also pulverizes the wood into dust of various dimensions, some too fine to be contained or filtered by a typical dust mask.

I don't particularly worry about the evidence related to pt in stable installations, I am concerned about the working with and occasional burning of it. I don't like the idea of routing or belt sanding it, though I assume that goes on in many a deck job. Nothing in the industry literature suggests any special precautions related to the CCA, so great is their effort (and the gov't's, compromised by the financial and political might of the forest products & homebuilders industry) to insist it is harmless. Now, are greater precautions required working with this material -- is it more dangerous -- or not? They carefully don't say. In fact, so many of their arguments are worded trickily that, if they were in a legal brief, I would be highly suspicious they were hiding the ball. I do not believe there is full disclosure.

I agree there is no evidence of a link between CCA and illness. But it may be out there still in areas untested, and I don't accept the generic argument that it is has been used for years "without problems." Epidemiological studies -- does X raise the chances of Y? -- are difficult to undertake, as recent toxic tort cases demonstrate. I'd like to see studies of arsenic & chromium (also toxic) in deckbuilders or mill workers, for example. And soil samples in areas where pt has been processed, e.g., the backyard of Mr. new deck owner. Out of $2.5 billion a year in revenue, this should be trivial enough.

Surely we are all tiring of the rumors -- growing in volume -- that pt is unsafe. These rumors are strong enough that multiple alternatives to CCA have been spawned with little justification other than they lack CCA. What's up?

(post #169496, reply #12 of 24)

touche' (I don't know how to get the true accent).

Rich Beckman

(post #169496, reply #13 of 24)

Well, this guy Jeff Anderton never came back here to tell us if it is CCA lumber he is using. I think everyone is assuming CCA. Ever noticed how many people seem to throw posts out there and never (it would appear) check the results?

As far as ToolBear's statement:

"When I have to work with it, I wear a Racal filtered air supply helmet, longsleeve clothing and exam gloves. (I'd love the HEPA filter version, but the filter/motor unit alone is $500)."

I got a real laugh out of that. I'd really like to see that on a job site in the August 100 degree heat!! He sounds like some guy my wife used to work with - used a "hankie" to open doors for fear of exposure to who knows what on the door knobs!!

(post #169496, reply #16 of 24)

Jeff I wont be that detailed because everybody else has covered that part of it. PT lumber is made with toxic chemicals that are locked into the lumber. Like asbestos it is not toxic when left untouched, when you start to cut it and create dust all that dust that floats around has the ability to be toxic. wear the appropriate protective gear, and what ever you do try not to rub your skin on your face without washing your hands it has a tendency to cause mild iritation to sensitive skin areas. As to the ammonia smell in the hole, has it one of your guys been peeing down in the hole because it was a great place to hide?

(post #169496, reply #17 of 24)

Ha! I was right!

What are you going to do? I would be inclined to believe that the odor will dissipate in time. Di they ship sopping wet lumber? Maybe you can stack and sticker it for a bit to let it dry out.

(post #169496, reply #18 of 24)

Ha! I was right!

What are you going to do? I would be inclined to believe that the odor will dissipate in time. Did they ship sopping wet lumber? Maybe you can stack and sticker it for a bit to let it dry out. Or make the yard fix the problem -- you deserve properly dried lumber.

(post #169496, reply #22 of 24)

It is VERY difficult to assess the effect of low-level exposure to things over a lenghty period of time. Like saccharine -- so, was it dangerous or not? I don't take the distrust everything "artificial" view, but mild skepticism is healthy.

I'll be cutting pt stairs today. The stringers are CCA, the rest an alternative I saved from another job (Kodiak). One aggravation -- that pt is so (&^%*! wet!