How was the lead soil cleanup level of 750 parts per million (ppm) set and how do we know it is adequate to address the environmental conditions potentially contributed to by historical smelter operations?

The Blackwell lead soil cleanup level was calculated utilizing a well-accepted environmental regulatory process that is referred to as a "site-specific risk assessment." This is a scientific evaluation that assesses the potential risk to human health and the environment posed by the lead soil concentration based on the actual conditions at the site. For example, a site-specific risk assessment looks at the soil and lead chemistry to assess to what extent lead from the soil that is ingested is likely to be absorbed into the body. The Blackwell site-specific risk assessment was performed with Oklahoma Department of Environmental Quality (ODEQ), and determined that the proper lead cleanup standard for Blackwell is 750 ppm. ODEQ determined that the 750 ppm cleanup standard for lead is protective of human health and the environment in Blackwell, including for children. The EPA monitored and reviewed the results of Blackwell's site-specific risk assessment and concurred with the use of this cleanup standard.

Setting the Record Straight - Lead Levels
The lawyers from Nix, Patterson & Roach LLP ("NPR") (who filed a proposed class action law suit against Blackwell Zinc and others) have suggested that a cleanup level of 400 ppm or lower would be more appropriate. NPR bases its claim on a general guideline or "screening level" used by the EPA to assess not whether cleanup is required but whether further investigation of residential lead concentrations is necessary. A guideline of this type is used by the EPA and state environmental agencies to determine whether a more "site-specific risk assessment" is advisable so that site-specific cleanup levels can be established. Use of this general guideline as a cleanup level in Blackwell is inappropriate because a rigorous"site-specific risk assessment" has been performed and site-specific cleanup levels established for Blackwell. In 2007, EPA Risk Assessor Jon Rauscher made the following statement regarding the lead cleanup level for Blackwell: "While 400 parts per million is a screening level for lead, or a level at which further investigation is warranted, EPA routinely sets higher cleanup levels on a site-specific basis." ODEQ News Release (Oct. 25, 2007).

As of Dec. 3, 2010, the ODEQ-approved supplemental soil program had sampled 3,967 properties in Blackwell. The sampling found that 548 of these properties (13.8 percent of the total sampled) had lead concentrations in the soil that exceeded the ODEQ cleanup standard. The sampling was conducted by environmental professionals with Shaw in accordance with ODEQ-approved work plans and quality control measures and under ODEQ oversight. The soil sampling results, however, do not tell us where the lead came from. The soil samples that exceed the cleanup standard represent the combined contribution of lead from a variety of possible sources in Blackwell that may include lead-based paint, leaded gasoline emissions, ammunition reloading, batteries, solder, vinyl miniblinds, ceramics, natural background levels and other sources.

How was the arsenic soil cleanup level of 50 parts per million (ppm) set and how do we know it is adequate to address the environmental conditions potentially contributed to by historical smelter operations?

Just like the cleanup standard for lead, a site-specific risk assessment was performed by the University of Oklahoma for Blackwell Zinc and the City of Blackwell under the oversight of ODEQ. Based on its own independent evaluation of the risk assessment, ODEQ determined that 50 ppm would be an appropriate arsenic cleanup standard that takes into account the specific circumstances of Blackwell. ODEQ has determined that the 50 ppm cleanup standard for arsenic is protective of human health and the environment in Blackwell. The EPA monitored and reviewed the results of Blackwell's site-specific risk assessment and concurred with the use of this cleanup standard.

Setting the Record Straight - Arsenic Levels
The lawyers from Nix, Patterson & Roach LLP ("NPR") (who filed a proposed class action law suit against Blackwell Zinc and others) have suggested that an arsenic cleanup level of 3.9 ppm would be more appropriate based on the Preliminary Remediation Goals ("PRG") set by Region 9 of the EPA, which is a single EPA office based in San Francisco. PRGs are another general guideline used by regulators only when a site-specific risk assessment has not been conducted and site-specific cleanup standards have not been calculated. The EPA has stated, "Chemical concentrations above [PRG] levels would not automatically designate a site as ‘dirty' or trigger a response action. However, exceeding a PRG suggests that further evaluation of the potential risks that may be posed by site contaminants is appropriate." ( U.S. EPA, "User's Guide and Background Technical Document for USEPA Region 9's Preliminary Remediation Goals (PRG) Table" (Apr. 2009)). As noted above, a site-specific evaluation was performed for Blackwell. Based on its own independent review of the evaluation, ODEQ developed a site-specific 50 ppm clean level for arsenic. EPA concurred with this cleanup level and supported ODEQ's decision to set 50 ppm as the cleanup level for arsenic in Blackwell.

Arsenic sampling data released by NPR include results of "background" samples from soils in the Blackwell area. Background samples represent naturally-occurring concentrations of metals collected from areas that are unaffected by historical smelter operations or other man-made sources. Concentrations of arsenic in NPR's background samples range from 5.2 ppm to 17.4 ppm. Accordingly, NPR's own data show that the naturally-occurring levels of arsenic in the soil around Blackwell already exceed NPR's suggested "cleanup standard" of 3.9 ppm. Given the natural concentrations of arsenic in Blackwell soil, similar concentrations of arsenic would be the minimum expected in residential yards and house dust. It would not make sense to impose a cleanup standard that would require removal of naturally occurring arsenic.

As of Dec. 3, 2010, the ODEQ-approved supplemental soil program had sampled 3,967 properties in Blackwell. The sampling was conducted by environmental professionals in accordance with ODEQ-approved work plans and quality control measures and under ODEQ oversight. The sampling found that 359 of these properties (9 percent of the total sampled) had arsenic concentrations in the soil that exceeded the ODEQ cleanup standard for arsenic. The soil sampling results, however, do not indicate the source of the arsenic.

Accordingly, the soil samples that exceed the cleanup standard represent the combined contribution of arsenic from a variety of possible sources in Blackwell that include naturally occurring arsenic and may include arsenic contributed by pesticides, fertilizer and other sources (e.g., treated railroad ties and telephone poles).

A Cleaner Blackwell
Lead exposure can come from a variety sources, including contaminated soil. Importantly, however, the Oklahoma Department of Environmental Quality (ODEQ) set the residential soil cleanup level for lead in Blackwell specifically to address the risk to children.

Today, in the United States, the highest risk factor for having Elevated Blood Lead Levels (EBLL) is living in a home built prior to 1950. See U.S. Centers for Disease Control and Prevention, "Preventing Lead Poisoning in Young Children" (Aug 2005). That is because the most likely exposure of lead is crumbling or deteriorating lead-based paint, which is typically found in certain older homes.

According to the 2000 Census, approximately 50 percent of the homes in Blackwell were built prior to 1950, compared to 18 percent in the rest of the state and 22.3 percent nationwide. Eighty-two percent of homes in Blackwell were built before the 1970s when the use of lead paint in homes was banned. Additionally, lead paint typically can have concentrations of lead many times greater than the byproducts from the zinc smelter. For many Blackwell residents, exposure to dust and paint chips from older painted surfaces is an important consideration when assessing their overall potential exposure to lead. Other common lead sources that can be a source of interior lead dust include soils impacted by  leaded gasoline emissions, ammunition reloading, solder, car batteries, vinyl miniblinds and ceramics.

For anyone who has questions related to blood lead levels, please contact the OSDH, the Kay County Health Department or visit the OSDH Childhood Lead Poisoning Prevention Program Web site.

If your child has not been tested already through the SoonerCare program administered by the state, you can have them tested at the Kay County Health Department or by your family physician.