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The United Creosoting National Priorities (NPL) list site is on Hilbig Road at Second Street, in Conroe, Montgomery County, Texas. The site was used for production of pressure treated creosoted wood products from 1946 until 1972. The on-site areas are currently owned by Sisco Construction Company, Clarke Distributing Company, and the residents of the Tanglewood East subdivision. ATSDR completed a health assessment for the site in January 1986. This addendum to the health assessment evaluates the 1984 and 1985 environmental sampling data in more detail and also evaluates additional environmental sampling data collected in 1990.

Contaminated soils and ground water have been detected both in industrial and residential portions of the original site vicinity. The primary contaminants of concern are polycyclic aromatic hydrocarbons, pentachlorophenol, and chlorinated dioxins/dibenzofurans (CDD/CDFs). The populations at greatest risk of exposure are workers involved with remediation activities and residents of Tanglewood East subdivision. Community health concerns include risks associated with gardening, the presence of odors around the residential areas, and potential exposures during remediation activities. Completed exposure pathways include ingestion and skin contact with contaminated soil. The potential for inhalation of particles released from contaminated soils will increase during, but not after, the soil excavation that will occur as part of the remediation process. Contaminated ground water is currently not being used in the area. This contaminated ground water is not likely to be used in the future due to the low yield of the aquifer. All water supply in the area is provided by the municipal water supply system. Based on the environmental data available for review, we conclude that the United Creosoting Company site poses a public health hazard for remediation workers and residents of Tanglewood East subdivision. Exposures to contaminated soil through skin contact and ingestion may have occurred in the past. Any potential present or future health hazards at this site will be eliminated by appropriate remediation.

As a follow-up to this evaluation, the Texas Department of Health (TDH) will conduct a site-specific surveillance study in the Tanglewood East subdivision. TDH will also prepare a summary of this Public Health Assessment Addendum and will make a copy available to each household in the Tanglewood East subdivision.



The United Creosoting Company National Priorities List (NPL) site is on Hilbig Road at Second Street in the city of Conroe, Texas. Appendix A contains a site location map for the United Creosoting Company. The site occupies 100 acres. The current owners are Clarke Distributing Company, Sisco Construction Company (formerly Conroe Construction Company), and the residents of the Tanglewood East subdivision.

The United Creosoting Company conducted operations at the site from 1946 until 1972. The process used by United Creosoting incorporated pressurized addition of pentachlorophenol and creosote into formed lumber. Site inspections conducted in 1972 and 1977 by the Texas Department of Water Resources noted that the site was being redeveloped for residential and light industrial use.

The United Creosoting Company site was added to the NPL in 1984. After the site's addition to the NPL, an immediate response action was conducted between January and April of 1984. The response action consisted of grading the area to divert run-off from the residential area, installing a fabric liner and a clay cap, and erecting a security fence. Demolition of six houses built directly over the former waste pits was completed in December, 1990. A eight-foot wooden privacy fence encloses the area.

A health assessment for the site was completed in January, 1986. Appendix B contains a copy of that health assessment. The original health assessment identified polycyclic aromatic hydrocarbons (PAHs) and pentachlorophenol as primary contaminants of concern. Chlorinated dioxins and chlorinated dibenzofurans (CDD/CDFs) have also been detected at the site. This addendum to the health assessment evaluates the 1984 and 1985 environmental sampling data in more detail and also evaluates additional sampling data collected in 1990.


Texas Department of Health staff members Dr. Suzanne Hahn and David Boston conducted a site visit on January 21, 1991. A windshield survey of the surrounding area was conducted, along with a walking tour of the site.

During inspection of portions of the site in the Tanglewood East subdivision, the following observations were noted: darkened areas of soil adjacent to demolished home sites; a recently erected wooden privacy fence enclosing vacant home sites, and areas of reduced vegetation growth. The staff members also noted children trespassing into the fenced area during the site visit.

The majority of the former industrial portions of the site area were under asphalt and the current industrial facility structures.

Very few physical hazards were observed around the site. At the time of the site visit, the area within the privacy fence contained only a trailer and the concrete slabs from the demolished homes. Physical hazards associated with this site are dangerous only to trespassers. Chemical risks associated with the vacant area are minimized by the presence of the privacy fence.


The city of Conroe is in Montgomery County within a densely wooded area of the San Jacinto River Basin. The 1980 census reported a population of 18,034 for the city of Conroe. The Chamber of Commerce reports a 1990 population estimate of 27,610.

The United Creosoting Company site is in the northeastern part of the city. There is an estimated population of 5,480 within a one-mile radius of the site. According to the 1980 census, an estimated 740 (14.9%) children under the age of 10 reside within the census tract that contains the United Creosoting Company site. Within that census tract, 95.7% of the residents are white. Appendix C contains a site map of the United Creosoting Company. The Tanglewood East subdivision is home to about 225 residents. In the past, some of the residents have grown gardens.

Land use in the Conroe area includes agriculture, an operating wood preserving facility, oil-related industries, and light industry. Many residents are employed in the Houston area. Also, part of Conroe's economy is based upon recreational opportunities provided by Lake Conroe, popular for sport fishing, swimming, skiing, and boating.

The United Creosoting Company site is within the Alligator Creek watershed. Alligator Creek borders the southwestern portion of the site and is a tributary to the San Jacinto River. Tanglewood East subdivision currently drains into the residential streets and then into Alligator Creek along culverts on Lilly Boulevard and Hancock Street. Sisco Construction runoff flows mainly to the west and into Tanglewood East. Clarke Distributing properties runoff drains directly into a ditch that feeds Alligator Creek. The creek is an intermittent, or wet weather creek.

The residents of Conroe and Tanglewood East subdivision get water from city utility sources. The city of Conroe municipal wells are installed in the Evangeline Aquifer. One city well is one mile from the site. Areas outside the city limits have access to the city water supply, but may get water from private wells.

D. Health Outcome Data

On February 25, 1991, Montgomery County Health Department (MCHD) officials were contacted about the availability of any health outcome data for residents in the vicinity of the United Creosoting Company NPL site. MCHD officials reported routinely collected birth, death, and fetal death certificates; they reported no additional health outcome data.

The Texas Department of Health Cancer Registry Division collects incidence data for cancer in Texas. Incidence data are incomplete for Texas Public Health Region 4 where United Creosoting Company NPL site is located. Therefore, that database was not used because the calculated incidence rates would underestimate the true incidence rates.

The Texas Department of Health Cancer Registry Division maintains cancer mortality files by county. The Cancer Registry Division staff obtains those data from the Texas Bureau of Vital Statistics. Cancer mortality data for 1981-1989 were analyzed for Montgomery County where United Creosoting NPL site is located. Cancer mortality data are not available by zip code in Texas.


To determine community concerns about the United Creosoting Company site, a public meeting was conducted on August 28, 1986 by the Environmental Protection Agency (EPA) in conjunction with preparation of the RI/FS and the public comment period for the Record of Decision. In attendance were residents and other interested parties living near the site. EPA held other meetings with the citizens on August 3, 1989 and July 31, 1990 as well as meetings on a continual basis to inform citizens of remediated efforts. We contacted the Montgomery County Health Department and the regional office of the Agency for Toxic Substances and Disease Registry (ATSDR) to determine additional community concerns. Following is a list of community health concerns.

  1. The effect of remediation on air quality.
  2. Concerns regarding odors in areas adjacent to the site.
  3. The risk associated with eating vegetables grown around the site.
  4. Risks associated with digging in gardens, and other related activities.
  5. Concerns that rashes might be related to site contaminants.
  6. The need for an epidemiological study to determine adverse health effects, if any, from past exposure to contaminants.

In December 1990, a reporter with a national women's magazine contacted an assistant epidemiologist, at the Cancer Registry Division of the Texas Department of Health. The reporter was concerned that there might be high rates of cancer in Montgomery County and that the elevated rates may have resulted from exposure to polycyclic aromatic hydrocarbons related to the United Creosoting Company site.

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