The United States Environmental Protection Agency (EPA) requested that the Texas Department of State Health Services (DSHS) and the Agency for Toxic Substances and Disease Registry (ATSDR) review pesticide residue data for wipe and wood chip samples collected from the Helena Chemical Company (HCC) facility in Mission, Hidalgo County, Texas. The purpose of this data review was to help identify potential public health concerns regarding future uses of the unoccupied onsite structures. The HCC facility consists of two adjacent properties previously used (1950-1972) for pesticide formulation. The facility currently includes five structures, which are either empty or filled with abandoned equipment and debris. While the site is located in a predominantly residential area, it is not operational. Under EPA oversight, investigations have been conducted at the site and on adjoining properties. Soil samples from the site and surrounding areas indicated the presence of pesticides (1). In 1982, the most highly contaminated soil was excavated to a depth of six inches, placed in an onsite repository, and capped with six inches of caliche and one inch of asphalt. No site visit was conducted for this consultation. Based on photographic evidence, access to the site appears to be unrestricted. Only the area around an above ground storage tank (AST) appears to be fenced. The wipe samples evaluated for this consultationwere collected in the onsite buildings during August 23-26, 2005, by URS Operating Services, Inc. Samples were collected from a warehouse (WHS), the North Mixing Plant (NMP), the South Mixing Plant (SMP), and a Shed (SHD). Sample locations and building designations were noted in the URS report (2). URS collected the wipe samples in accordance with EPA Standard Operating Procedure (SOP) no. 2011, which states that the sample should be collected using solvent-wetted gauze wiped over a 12-square inch (12 inches OE 12 inches) area. Two individual samples and 34 composite (several wipe samples placed together in one sample jar) samples were collected. In addition, two composite wood chip samples were collected from wood beams in the ceilings of the SMP and NMP. The URS report (2) did not describe sampling procedures and protocols used to collect wood chip samples.