Chemical Treatment of Wood

In 1995, the wood preserving industry reported $3.65 billion in annual gross sales. In the same year, total volume of treated wood produced reached 578,874,000 cubic feet.19 

The largest use of pentachlorophenol and other oilborne solutions is in the treatment of utility poles. Of the 32,764,000 cubic feet of all wood treated with penta and oilborne solutions, 93 percent, or 30,617,000 cubic feet, is used in

How many poles are treated with which chemicals? 

Chem.	Treated Wood (1,000  feet3)	Percent
Penta/Oil	30,617	45
Arsenicals	29,215	42
Creosote	8,941	13
TOTAL	68,773	100
source: American Wood Preservers Institute, 1995

the production of utility poles. Of the 450,596,000 cubic feet of all wood treated with arsenicals, six percent, or 29,215,000 cubic feet, go into utility poles. In other words, the vast majority of pentachlorophenol is used on utility poles.20 Nevertheless, the treatment of utility poles are almost evenly split between penta and CCA, with 45 percent treated with penta, 42 percent with CCA and 13 percent with creosote. 

More Info:
Wood Preserving Facilities and Contaminated Sites by State 

Treatment process

The pressure-treating process involves placing the wood in a pressure-treating vessel where it is immersed in the preservative and then subjected to applied pressure. The excess penta is vacuumed from the vessel and the treated wood is removed, inspected, stored, and shipped. In the non-pressure process, which is used for short-term wood protection in construction where the wood will be protected from exposure to soil or weather through brick or cement barriers, penta is applied to the surface of wood by spraying, brushing, dipping, and soaking. This process is also used to control sapstain fungi by passing green lumber through a spray tunnel or by dipping the wood.25 

 

“Tim Skaggs died on October 17, 1991 at the age of 41 from acute lymphoblastic leukemia. Tim worked for Simpson Lumber Company at its Arcata mill starting at age 21. His initial employment as a night shift laborer resulted in his working at various jobs, including assignments to the paint line department where he handled and sawed lumber treated with Woodlife, a penta wood preservative manufactured and sold to Simpson by Champion. Tim's exposure to this dangerous and defective chemical during the period 1971 through late 1972 caused Tim's leukemia and that of his co-workers at the Arcata mill. The diagnosis of leukemia in Tim some 17 years after being exposed to this known carcinogen was consistent with the latency period for this type of chemically induced cancer. The California State Department of Health's report of that investigation documented three leukemias, including Timothy Skaggs, and one non-Hodgkins lymphoma at the Arcata plant.”  Richard Alexander, Dioxin in pentachlorophenol: A case study of cancer deaths in the lumber industry, 1996, citing "Evaluation of a Potential Cluster of Hematopoietic Cancers Among Workers in a Wood Manufacturing Mill in California," California Department of Health Services, Berkeley, April 12, 1990.

Toxic releases from treatment sites

• Arsenic has been found in at least 781 NPL sites;26 
• Penta had been found at least 314 NPL sites;27 
• Chromium has been found in at least 386 hazardous waste sites on the NPL;28 
• Copper has been found at least 210 NPL sites; and,29 
• Creosote has been found at least 38 of NPL sites.30 

Maps:

Wood Preserving Plants (number per state)

 and
 
National Priority List Sites
Contaminated with Penta, Creosote, Chromium or 
Arsenic
[Wood treatment sites and other sites]

Drip residues is considered "one of the major potential sources of air-borne CCA components in treatment plants."34 Penta treated wood, "particularly immediately after treatment, emits PCP to the air and the wood may exude excess preservative."35 

Worker exposure

Exposure to wood preservative chemicals is highest among workers at wood treatment facilities.36 So much illness has resulted from worker exposure to pentachlorophenol that it is seen as a significant source of income for attorneys pursuing toxic torts.37 One study found that mean pentachlorophenol levels in the blood of workers using penta ranged from 83 to 57,600 parts per billion.38 Exposure to pentachlorophenol at maximum air concentrations allowed by Occupational Safety and Health Administration (OSHA) are estimated to produce blood levels one hundredth as high as the maximum found in this study.39 EPA estimated the lifetime cancer risk of a worker in a wood treatment plant using inorganic arsenicals as ranging from two in 100 to more than one in ten. Cancer risk for workers using penta were based on the dioxin contaminant, rather than all the ingredients. Nevertheless, cancer risk was estimated to range from seven in 1,000 to more than one in 100. EPA did not perform a quantitative risk assessment for workers exposed to creosote.40 

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