Is Wolmanized wood safe around people, plants, and pets?

Pacific Biomedical Research Center, 1977

In Hawaii, where over 45,000 homes had been built almost entirely of Wolmanized wood, a study was conducted by the Pacific Biomedical Research Center of the University of Hawaii to determine any possible effect on the health of carpenters. The study covered periods both before and after Wolmanized wood was introduced in Hawaii. The authors of this study conclude that exposure to dust from such wood is not associated with increased risk of total cancer, lung cancer or lymphatic cancer. These data, which constitute the best epidemiological evidence available on treated wood, clearly show that excess respiratory cancer mortality was not observed in the carpenters exposed to arsenically-treated sawdust. In fact, OSHA has acknowledged this difference between inorganic arsenic and the arsenate compounds found in treated wood. OSHA notes:

"In the Budy-Rashad study, the carpenters were not exposed to pentavalent arsenic, but rather to a stable arsenic-wood complex. Thus, carpenter exposure to this arsenic-wood complex cannot be considered a priori equivalent to exposure to unbound pentavalent arsenic. "  (43 Federal Register 19,599 - May 5, 1978)

Hickson Corporation, 1992

Three raised bed structures were constructed: one built with untreated wood, one with Wolmanized wood and one with Wolmanized Extra water repellent lumber. These structures were divided into individual compartments, 8.5" x 10.5" and 5.5" high, so that the bottom and all sides of each compartment were of the same material.

Various vegetables were planted in the structures. After 12 weeks, the vegetables were harvested and portions were analyzed for CCA components. Vegetables obtained from a local grocery store were also analyzed.

All vegetables, including those grown in untreated compartments and those purchased in a store, contained minuscule amounts of each CCA element that were well within accepted parts per million limits.

Consumer Product Safety Commission, 1990

As part of the 1990 Playground Equipment Handbook project, a study was undertaken by the Health Sciences (HS) staff to estimate the risk of skin cancer from dislodgeable arsenic on pressure-treated wood playground equipment.

Arsenic has been associated with human skin cancer when chronically ingested. The wood preservative used in most of the U.S. wood playground equipment is chromated copper arsenate (CCA). Prior to this study, inadequate data and procedures existed for assessing the cancer risk to children playing on pressure-treated wood playground equipment as indicated by the Environmental Protection Agency (EPA) (1981, 1984) and the California Department of Health Services (1987).

Leaching experiments by HS staff demonstrated that arsenic can be released from pressure-treated wood. Seven playground equipment wood samples were collected by CPSC field staff from major U.S. manufacturers. One comparison sample of unfinished pressure-treated wood was purchased at a retail store. A method was developed by HS for testing dislodgeable arsenic on the eight wood samples.

The estimated risk of skin cancer for the five out of seven samples from manufacturers which were below the detection level of dislodgeable arsenic, was less than 1 in a million, which is a negligible risk. The estimated risk for the two out of seven samples that had detectable levels was 3-4 in a million. This is a small risk that should be reduced further if it can be practically accomplished.

The estimated risk for the comparison sample was somewhat higher (8-9 in a million). This suggests that a possible hazard might be created when playground equipment is built with unfinished pressure-treated wood from retail sources. (Note: the comparison sample was rough sawn lumber which is not acceptable for playground equipment according to AWPA standard C17.)

A report to the California State Department of Health Services; Consultants in Epidemiology and Occupational Health, Inc., 1984 Data collected by the California State Department of Health Services (DOHS) indicate that arsenic can be transferred from the surface of CCA-treated wood by rubbing with either tissues or the hands. The potential risk to children from licking their hands after playing on playground equipment built with CCA-treated materials can be calculated and compared with other exposures and risks. Analysis of the scientific data in published and unpublished studies lead the authors to the following conclusions:

1. It appears that the maximal Arsenic (V) exposure estimate for children from use of playground equipment is within the normal variation of Arsenic (V) exposure for children;
2. The maximum estimate of the skin cancer risk associated with such exposure approximates the skin cancer risk from the sunlight experienced during the play period;
3. The scientific studies upon which the association of Arsenic (V) and skin cancer is based are weak; and
4. Finally, the sampling methodology used to measure the potential exposure from wood products is uncertain with little reproducibility by individual samplers or between investigators.

South Carolina Department of Natural Resources
Marine Resource Division, 1995

This study examined the concentrations and biological effects of certain metals and organic compounds typically found in wood preservatives used to protect dock pilings, bulkheads, and other wooden structures from decay. The study focused on leachates from private docks in South Carolina macrotidal creek systems. Copper, chromium, arsenic, and polynuclear aromatic hydrocarbons (PAHs) were measured in composite samples of surficial sediments and naturally occurring oyster populations (Crassostrea virginica) &nbspfrom creeks with high densities of docks, and from nearby reference creeks with no docks. Sediments from all but one site had metal and total PAH concentrations which were below levels reported to cause biological effects. Solid phase Microtex® bioassays using whole sediments and rotifer bioassays using sediment pore water showed no significant differences in acute toxicity between creeks with and without docks. Oysters growing directly on dock pilings had significantly higher concentrations of copper than oysters growing at least 10 m away; however, there was no significant difference in the physiological condition of these oysters. Four-day field bioassays measuring percent survival of mummichogs (Fundulus heteroclitus), &nbspmud snails (llyanassa obsoleta), &nbspjuvenile red drum (Sciaenops ocellatus), &nbspand juvenile white shnmp (Penaeus setiferus) &nbspshowed no significant differences between sites near to and distant from newly constructed docks. Hatchery-reared oysters showed no significant differences between dock and reference sites in percent survival, growth, or bioaccumulation of metals after six weeks of exposure. Our results suggest that, in macrotidal estuarine environments, wood preservative leachates from dock pilings have no acutely toxic effects on four common estuarine species, nor do they affect the survival or growth of juvenile oysters over a six-week time period. In some cases, metal leachates may accumulate in sediments and oysters immediately adjacent to pilings, but do not appear to become concentrated in sediments or oysters elsewhere in the same creeks.

Springborn Laboratories, Environmental Sciences Division, 1993

Leachate obtained during a 28-day period from CCA-treated and untreated pilings was dosed onto two sediment types: low organic carbon (LOC) (less than 1%) and high organic carbon (HOC) (greater than 4%). Ampelisca abdita groups were exposed to sediment of each type dosed with one of three concentrations of leachate (10%, 50% or 100% leachate). The 10-day exposure was maintained under static conditions with continuous lighting to provide maximum exposure. Survival of the organisms during the 10-day exposure period was the biological endpoint used to establish the effects of exposure.

Analyses established that copper bound to both the LOC and HOC sediments remained bound and did not desorb into the interstitial or overlying water. Analysis showed that little or no chromium was released from treated pilings over 28 days. Uptake of chromium into the LOC sediment was neglible and only a minimal amount of chromium adsorbed to the HOC sediment. Chromium in the sediment generally did not move into interstitial water but did move into overlying water from both sediments. Approximately 59.5 mg arsenic/m2 of treated wood surface area leached from the treated pilings, but arsenic did not appear to adsorb onto either sediment type, and in almost all cases, did not move into interstitial or overlying water.

Finding that leachate from untreated pilings had a greater adverse effect on organism survival than leachate obtained from CCA-treated wood pilings, the study's author concluded that the primary constituents of the CCA-treated wood pilings were not present in the leachate at concentrations which would adversely affect the survival of the organisms. (Note: The adverse effects observed with leachate from untreated pilings were presumed due to naturally occurring compounds present in untreated wood, which the author hypothesized were extracted or altered in the treatment process.)

M. Comfort, Tasmanian Parks and Wildlife Service, 1993

The effects of CCA-treated timber used for an extensive network of raised walkways or walking "tracks," on a pristine Tasmanian wilderness environment were evaluated. Three biophysical studies were conducted: soil sampling to determine whether leaching of chemicals was occurring, a field experiment examining whether CCA-treated sawdust affects the soil invertebrate population, and analysis of the germination rates of plants grown beneath a layer of CCA-treated sawdust.

Analysis of the soil samples revealed that minimal leaching of the chemicals from CCA-treated timber occurred. Although some values for the concentrations of copper and chromium were above background levels, none reached contamination levels set by Australian standards. The CCA elements had not moved far from the track and concentrations of CCA elements decreased with increasing soil depth.

The study suggested that the presence of CCA-treated sawdust after six months may have reduced the total number of invertebrates, but that impact was determined to be very localized. Vegetation productivity did not appear to be affected by the CCA timber track structures, and CCA-treated sawdust did not affect the germination rates of Leptospermum scoparium in a glass house trial.