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Review of August 2001 Ambient Air Data



The Agency for Toxic Substances and Disease Registry (ATSDR) received a request from U.S.Environmental Protection Agency (EPA) Region 10 to evaluate ambient air data for Poles, Inc.,collected in August 2001, and determine whether airborne pentachlorophenol (PCP) andassociated chemicals pose a health hazard to people at the neighboring school or residences (1).

Poles, Inc., located in Oldtown, Idaho, just west of Priest River, is an open vat thermal wood-treating facility, using pentachlorophenol (PCP) as a wood preservative. The facility is closedduring December, January, and February, and operates the other 9 months of the year. Thenearest residence is approximately 400 feet north of the facility and an elementary school islocated approximately 500 feet south of the facility. The elementary school is approximately30 feet higher in elevation than the site. In 1999, an old wood-fired boiler was replaced by a newoil-fired boiler, reducing the treatment process from 13 hours to 8 hours. Because the facilityuses only one dip tank, a maximum of 2 to 2.5 batches are treated a week (2).

In fall 2000, several community members and schoolteachers complained about strong odors emanating from the facility, and expressed concerns of possible health effects. In response to these concerns, the owner changed his schedule, treating the poles during the evening instead of during the day, to reduce possible exposure of nearby community members to airborne PCP. In August 2001, Ecology and Environment, Inc. collected 27 ambient air samples at eight locations on and around the facility during 3 consecutive days. All samples were collected in a 23-hour period with approximately 300 cubic meters total sample volume and analyzed for semivolatile organic compounds (SVOCs) using EPA Method TO-13A. See Table 1 for sampling location description and Table 2 for summary of analytical data.


Twelve SVOCs were detected in ambient air samples. The levels of all detected chemicals, except PCP and 2-methylnaphthalene as noted below, were below their respective health-based guidelines. PCP was found at levels ranging from non-detect to an estimated maximum of 1.48 µg/m. The Idaho ambient air standard for PCP is 25 µg/m based on noncancer effects and the EPA Region 9 preliminary remediation goal (PRG) for PCP is 0.056 µg/m based on carcinogenicity (2,3).Some issues related to this site are as follows:

  • Due to the chemical and physical properties of PCP, the air pathway is not expected to bea primary route of exposure at this site. Oral ingestion and dermal contact through soiland water pathways should be considered when data becomes available.

  • There are no known health guidelines for inhalation exposure for PCP. The PRG cited inthe data tables is not an appropriate screening value to assess health concerns at the site.First, the PCP PRG value was calculated using a route-to-route extrapolation. Second,PRG is based on a default exposure frequency of 30 years, 350 days per year. Third, PRGcorresponds to a fixed level of 1-in-1 million cancer risk. Wind direction variability andthe limited frequency with which logs are treated at the site will not permit exposuresfrequent enough to cause long-term health effects. Calculation of a realistic exposurescenario at the site indicates no apparent increased cancer risk.

  • The sample quantitation limits were above the PRG value; however, when calculating theaverage dose using half of the detection limits where no PCP was detected, the levelswere below the PRG values.

  • PCP has been identified in at least 313 of the 1,585 hazardous waste sites on the NationalPriorities List (NPL). No site was found in the HazDat database where PCP in airpresented a public health hazard. For example, Laidlaw Environmental Services Facilityin South Carolina had a completed air pathway for PCP, but it was determined to be noapparent public health hazard.

  • 2-methylnaphthalene is another chemical to be evaluated. Because there is no PRG value for 2-methylnaphthalene, the PRG value for naphthalene was used. The maximum value for 2-methylnaphthalene is higher than this PRG value, as well as for the ATSDR chronic inhalation reference-dose media evaluation guide (RMEG) value. However, the RMEG is based on the lowest observed adverse effect level (LOAEL) for animal exposures with a safety factor of 1,000. The LOAEL is approximately 1,280 µg/m (4). Also, the RMEG is a screening value that uses an exposure scenario inappropriate for the site. Therefore, current site-related exposures are not expected to result in adverse health effects.

  • The following limitations for this analysis are noted. (1) The data analysis pertains tocurrent exposure levels only. No conclusions can be drawn about past exposure. (2) Thesample method reporting limits for the data exceed the PRGs.


On the basis of available data and the above discussions, ATSDR concluded that currentexposure to PCP and 2-methylnaphthalene at this site through the air pathway is no apparentpublic health hazard because (1) exposures will not cause imminent adverse health effects in thegeneral population, which (2) will have no apparent increased risk of getting cancer from long-term exposure.


  1. Inform the public that there is no apparent public health hazard posed by the levels of PCP and 2-methylnaphthalene measured in the air.

  2. Evaluate oral ingestion and dermal contact through soil and water pathways when databecomes available.


  1. Agency for Toxic Substances and Disease Registry. Technical assistance request to theExposure Investigations and Consultations Branch from Karen Larson, ATSDR Region 10representative, concerning possible air contamination at the Poles, Inc., site. Atlanta: US Department of Health and Human Services; October 25, 2001.

  2. Agency for Toxic Substances and Disease Registry. Health consultation for Poles,Incorporated, wood treatment facility. Atlanta: US Department of Health and HumanServices; 2001 Sep 19.

  3. US Environmental Protection Agency. Region 9 preliminary remediation goals. WashingtonDC: US Environmental Protection Agency; 2001. Available at URL:

  4. Agency for Toxic Substances and Disease Registry. Toxicological profile for naphthalene (update), Atlanta: US Department of Health and Human Services; 1995 Aug.


Jane Zhu
Environmental Health Scientist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation

Kara Fincham
Program Evaluation, Records, and Information Services Branch
Division of Health Assessment and Consultation

Reviewed by

Karen L. Larson, PhD
Regional Representative
Office of Regional Operations
Agency for Toxic Substances and Disease Registry

Gregory M. Zarus
Strike Team Leader
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

Maurice West, PE, DEE
Deputy Branch Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

Table 1.

Air Sampling Locations/Descriptions for Poles, Inc. August 22-25, 2001
Location ID Description of sample location
PY04AM Background
PY01AM Metstation (downwind during all three sampling events)
PY02AM Near bluff (downwind during all three sampling events)
PY03AM Residence (downwind only during August 22-23 sampling event)
PY05AM Next to process area (on-site) (downwind during all three sampling events)
PY06AM Inside school
PY07AM Across river (downwind during all three sampling events)
PY08AM Downwind

Table 2.

Summary of Air Samples Pentachlorophenol (PCP) Analytical Results Poles, Inc. Oldtown, Idaho (µg/m3)
Location ID August 22-23 August 23-24 August 24-25
PY04AM 0.18 U 0.18 U 0.16 U
PY01AM 0.16 U 0.18 U 0.03 JQK
PY02AM 0.10 JQK 0.03 JQK 0.06 JQK
PY03AM 1.48 JQK 0.16 U 0.16 U
PY05AM 0.01 JQK 0.63 JL 0.49 JL
PY06AM* 0.18 U 0.16 U 0.16 U
PY07AM 0.05 JQK 0.16 U 0.15 U
PY08AM R 0.16 U 0.14 U

*indoor air sample in school
U = The analyte was detected. The associated numerical result is the sample quantitation limit.
J = The analyte was positively identified. The associated numerical result is an estimate.
K = Unknown bias.
L = Low bias.
Q = Analyte detected below the adjusted sample quantitation limit.
R = Rejected.

Demographic Statistics
Figure 1. Demographic Statistics

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