The Preservative and the Poison: Pentachlorophenol at Historic Wood Treatment Facilities
By Paul E. Rosenfeld, M.S., Ph.D., Principal Environmental Chemist, RoseyFields LLC, Santa Monica, California
A wood preservative with its own distinct toxicological legacy
Pentachlorophenol (PCP) was used for decades as a wood preservative, particularly for utility poles and railroad ties, and Dr. Paul E. Rosenfeld, M.S., Ph.D.’s published research on communities near wood treatment facilities has specifically evaluated PCP as one of several chemical insecticides used in this industry, alongside chromated copper arsenate and creosote (Hensley et al., 2007).
Why PCP requires separate analysis from the dioxins in the same facilities
Wood treatment facilities using pentachlorophenol frequently also generated dioxin and furan contamination as manufacturing byproducts of the PCP formulation process itself, meaning a rigorous investigation of these communities must evaluate both PCP and its associated dioxin/furan contaminants as distinct, if related, exposure concerns rather than treating either as a proxy for the other.
PCP’s own toxicological profile
Beyond the dioxin contamination frequently associated with technical-grade PCP, pentachlorophenol itself has documented health effects including liver and kidney toxicity, and IARC classifies pentachlorophenol as carcinogenic to humans (Group 1), a classification distinct from and independent of its associated dioxin contaminants (IARC, Pentachlorophenol and Some Related Compounds).
The regulatory phase-out and continuing legacy exposure
EPA has restricted pentachlorophenol to certified applicator use only since the 1980s, effectively eliminating most general consumer uses, but legacy contamination at former wood treatment facility sites and in treated wood products installed decades ago, including utility poles and railroad ties still in active service, continues to present potential exposure pathways today (US EPA, Pentachlorophenol Reregistration).
Attic dust and blood lipid sampling as a combined evidentiary approach
Dr. Rosenfeld’s published research on communities surrounding wood treatment facilities combined attic dust sampling, providing a historical airborne deposition record, with blood lipid analysis of current and past residents, providing direct biological evidence of body burden, an approach that connects environmental contamination evidence directly to individual exposure evidence rather than relying on either alone (Hensley et al., 2007; Feng et al., 2010).
A specific documented community example
One of Dr. Rosenfeld’s published studies specifically examined a wood treatment facility that had operated in southern Alabama for approximately 35 years, releasing dioxins and other hazardous substances including PCP, chromated copper arsenate, and creosote into the surrounding community, with attic dust sampling performed in structures within a one-mile radius of the former facility (Hensley et al., 2007).
Groundwater and soil pathways at former treatment facility sites
Beyond the airborne deposition pathway addressed by attic dust sampling, PCP and its associated contaminants can persist in soil and migrate to groundwater at former wood treatment facility sites, requiring the same kind of hydrogeologic fate-and-transport assessment applied at other legacy industrial sites to evaluate drinking water and soil contact exposure pathways.
Why creosote and PCP facilities require distinguishing between the two preservatives
Because both creosote and PCP were historically used, sometimes at the same facility during different operational periods, as wood preservatives, and because creosote’s polycyclic aromatic hydrocarbon toxicological profile differs substantially from PCP’s chlorophenol and dioxin-related profile, a rigorous facility investigation must identify which preservative was used during which historical period rather than assuming a single contaminant profile applied throughout a facility’s operating history.
Regulatory benchmarks applicable to reconstructed exposure
EPA’s IRIS toxicological review of pentachlorophenol and associated soil and groundwater screening levels provide the quantitative benchmarks against which reconstructed historical exposure at former wood treatment facility communities is evaluated, applied alongside the separate toxicity equivalency framework for any associated dioxin and furan contamination (US EPA, IRIS: Pentachlorophenol).
Why legacy wood treatment sites remain a continuing environmental forensics subject
With hundreds of former wood treatment facilities identified on EPA’s Superfund and state cleanup program lists nationally, and with treated wood products from the PCP era remaining in active infrastructure use, the combined attic-dust, blood-lipid, and soil-and-groundwater investigative methodology developed in this body of research remains directly applicable to evaluating other legacy wood treatment communities. Visit RoseyFields.com to read more about Dr. Rosenfeld’s wood treatment facility environmental forensics work.
References
1. Hensley AR, Scott A, Clark JJJ, Rosenfeld PE. Attic dust and human blood samples collected near a former wood treatment facility. Environ Res. 2007;105:194-197.
2. Feng L, Wu C, Tam L, Sutherland AJ, Clark JJ, Rosenfeld PE. Dioxin and furan blood lipid and attic dust concentrations in populations living near four wood treatment facilities in the United States. J Environ Health. 2010;73(6):34-46.
3. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Pentachlorophenol and Some Related Compounds. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 117. Lyon, France: International Agency for Research on Cancer; 2019.
4. US Environmental Protection Agency. Toxicological Review of Pentachlorophenol. Integrated Risk Information System (IRIS). Washington, DC: US EPA.
5. US Environmental Protection Agency. Reregistration Eligibility Decision for Pentachlorophenol. Washington, DC: US EPA; 2008.
6. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Pentachlorophenol. Atlanta, GA: US Department of Health and Human Services; 2001.
7. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Wood Creosote, Coal Tar Creosote, Coal Tar, Coal Tar Pitch, and Coal Tar Pitch Volatiles. Atlanta, GA: US Department of Health and Human Services; 2002.
8. Tam LK, Wu CD, Clark JJ, Rosenfeld PE. Methods for collecting samples for assessing dioxins and other environmental contaminants in attic dust: a review. Organohalogen Compd. 2008;70:000527-000530.
9. US Environmental Protection Agency. EPA’s Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments. Washington, DC: US EPA; 2010.
10. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Chromium. Atlanta, GA: US Department of Health and Human Services; 2012.
11. US Environmental Protection Agency. Regional Screening Levels for Chemical Contaminants at Superfund Sites. Washington, DC: US EPA.
12. Rosenfeld PE. RoseyFields LLC: Wood Treatment Facility Environmental Forensics. Santa Monica, CA: RoseyFields LLC; 2026.
13. US Environmental Protection Agency. Revisions to the Guideline on Air Quality Models. 40 CFR Part 51, Appendix W. Fed Regist. 2017;82(10):5182-5235.
14. Wu C, Tam L, Clark J, Rosenfeld P. Dioxin and furan blood lipid concentrations in populations living near four wood treatment facilities in the United States. In: Air Pollution XVII: Proceedings of the Seventeenth International Conference on Modeling, Monitoring and Management of Air Pollution. Southampton, UK: WIT Press; 2009.