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EnSys, Inc.-PCB RISc Soil Test Kit-An enzyme immunoassay for fast, semi-quantitative field measurements of polychlorinated biphenyls in soil

Final Decision to Certify Hazardous Waste Environmental Technology

The following is excerpted from:

Published Weekly by the Office of Administrative Law
Register 94, No. 27-Z
July 8, 1994
pp 1101-1104

The California Environmental Protection Agency, Department of Toxic Substances Control (Department) has made a final decision to certify the following company’s hazardous waste environmental technology listed below:

EnSys, Inc.
P.O. Box 14063
Research Triangle Park, NC 27709

PCB RISc™ Soil Test Kit, an enzyme immunoassay
for fast, semi-quantitative field measurements
of polychlorinated biphenyls in soil.

A new law effective January 1, 1994 (Chapter 412, Statutes of 1993, Section 25200.1.5., Health and Safety Code, enacted by Assembly Bill 2060, Weggeland), authorizes the Department to certify the performance of hazardous waste environmental technologies. Only technologies that are determined to not pose a significant potential hazard to the public health and safety or to the environment when used under specified operating conditions and which can be operated without specialized training and with minimal maintenance may be certified. Incineration technologies are explicitly excluded from the certification program.

The purpose of the certification program is to provide an in-depth, independent review of technologies at the manufacturers’ level to facilitate regulatory and end-user acceptance and to promote and foster growth of California’s environmental technology industry.

The Department makes no express or implied warranties as to the performance of the manufacturer’s product or equipment. The end-user is solely responsible for complying with the applicable federal, state, and local regulatory requirements. Certification does not limit the Department’s authority to require additional measures for protection of public health and the environment.

By accepting certification, the manufacturer assumes, for the duration of certification, responsibility for maintaining the quality of the manufactured equipment and materials at a level equal to or better than was provided to obtain certification and agrees to be subject to quality monitoring by the Department as required by the statute under which certification is granted.

DTSC’s notice to certify was published in the California Regulatory Notice Register Volume 94, No. 27-Z. The DTSC’s final certification shall be effective from August 8, 1994 to August 8, 1997.

Additional information supporting DTSC’s final certification decisions is available from:

California Environmental Protection Agency
Department of Toxic Substances Control
Office of Pollution Prevention and Technology Development
P.O. Box 806
301 Capitol Mall, 1st Floor
Sacramento, California 95812-0806
(916) 322-3670

A description of the technology to be certified, the final certification statement and the certification limitations for the technology follows:

EnSys, Inc.
PCB RISc™ Soil Test System
(Monoclonal Test)

Technology Description

The technology is an enzyme immunoassay for fast, semi-quantitative field measurements of polychlorinated biphenyls (PCBs, as Aroclors) in soil. The reaction is performed on a methanol extract of a small sample of the soil. The EnSys system offers one or more semi-quantitative detection levels which can be customized for each project. The minimum detection level is 1 ppm for Aroclor 1248 with lower minimum detection levels of 0.4 ppm for Aroclors 1254 and 1260. The lowest detection level for a particular situation can be set at or above the minimum detection level. The second (and third, if needed) detection level can be set at higher levels by a factor of four or more, while maintaining the claimed accuracy and precision up to a maximum detection level of 500 ppm in soil. The manufacturer provides testing reagents and utensils, including a sample weighing balance and a photometer for field use, a user manual, material safety data sheets, field data recording forms, and instruction in the use of the testing system.

Certification Statement

Under the authority of Section 25200.1.5 of the California Health and Safety Code, the Department hereby certifies the PCB RISc™ Soil Test kit manufactured by EnSys, Inc. as a measurement technology. The test kit consists of a semi-quantitative immunoassay system for the detection of PCBs, as Aroclor mixtures. Provided that the immunoassay is used properly, the minimum detection level of Aroclor 1248 is 1 ppm levels, with lower minimum detection levels of 0.4 ppm for Aroclors 1254 and 1260. For the other Aroclors, higher target levels apply. The technology is applicable to testing of soil or soil-like material which is not highly contaminated with oil or other non-aqueous phase liquids (NAPLs). The efficiency of the test depends on the extraction of PCBs from the test soil into a methanol solution. The efficiency of extraction is reduced in excessively moist soils and may be affected by high clay or organic content of the soil. It is recognized that the calibration is biased so as to minimize the possibility of false negative results; other limitations are set forth below. The Department’s findings are described in greater detail in an evaluation report.

Limitations of Certification

The Department makes no express or implied warranties as to the performance of the manufacturer’s product or equipment. The Department has not conducted any bench or field tests to confirm the manufacturer’s performance data. Nor does the Department warrant that the manufacturer’s product or equipment is free from any defects in workmanship or material caused by negligence, misuse, accident, or other causes.

The Department believes, however, that the manufacturer’s product or equipment can achieve performance levels set out in this Certification. Said belief is based on a review of the data submitted by the manufacturer and other information, and is based on the use of the product in accordance with the manufacturer’s specifications.

Specific Conditions

  1. EnSys, Inc. shall inform the user that the detectable concentrations apply to a specified Aroclor (Aroclor 1248), that the sensitivity of the assay to the various Aroclors does vary, and that it is important for the user to know what type of Aroclor is being tested and the general range of error if there is a different Aroclor, or a mixture of Aroclors, or if the Aroclors are weathered.
  2. EnSys, Inc. shall keep users abreast of known interferences and matrix effects. As a minimum, users should know that the assay is not suitable for oily matrices and soils containing 1 to 10 percent or higher levels of petroleum hydrocarbons; also organic solvents may affect recovery. User should be aware of unacceptably low extraction efficiency in wet soils (water content of 30 percent or higher); for consistent results, soils should be dry and results expressed per gram of dry or dried soil.
  3. EnSys, Inc. shall furnish the product with Material Safety Data Sheets for the instruction of users in the safety aspects of the product and its application.
  4. User’s Guide (ref.2) shall state under “Important Notice” that the manufacturer recommends that the user attend an eight-hour training/certificate course given by an EnSys, Inc. trainer or be trained by an experienced user.
  5. The User Guide shall contain a clear indication of the shelf life of the reagents and a warning on the deterioration of reagents at high temperatures as may be encountered in transit and in field use.

Basis for Certification

Certification is based on a review of:

  1. Application to the Department dated 24 January 1994;
  2. User’s Guide, 5th rev., 1 September 1993;
  3. PCB RISc™ Product Field Studies (Summary of external validation studies with tabular material), undated;
  4. PCB RISc™ Soil Kit Monoclonal Test, Internal Validation Results, EnSys, Inc. 30 June 1992;
  5. PCB RISc® Polychlorinated Biphenyls Soil Test, Technical Guide, November 1992;
  6. PCB Soil Test Stability, graph, FAX from EnSys, Inc. to G.W. Fuhs, 17 February 1994;
  7. DOE Methods for Evaluating Environmental and Waste Management Samples, U.S. Department of Energy, Assistant Secretary for Environmental Restoration and Waste Management, DOE/EM-0089T, October 1993 (Method OS020); and
  8. U.S. EPA Method 4020, Soil Screening for Polychlorinated Biphenyls by Immunoassay, U.S. EPA Office of Solid Waste, SW-846 Method Revision Draft 1, October 1992.

Recommended Applications of the Test System

The immunoassay is for the semiquantitative determination of PCBs in terms of a commercial mixtures of PCBs (Aroclor 1248) that has been used in the design and calibration of the assay. Conversion factors are applied to the results for Aroclors to which the assay responds differently. Unknown PCB mixtures need to be characterized by a reference method and a conversion factor needs to be determined which reflects the immunoassay response of that mixture relative to the response of Aroclor 1248. Without such an adjustment, results can be either high or low, depending on the affinity for the assay’s antibodies of an unknown PCB mixture. A semiquantitative determination will provide a response, interpreted as either positive or negative, at one or several predetermined detection or target levels. Target levels are usually chosen to have relevance to a specific situation.

A comprehensive process of developing data quality objectives (DQO) was published by U.S. EPA under the U.S. Superfund Program. It provides guidance for analytical method QA/QC as applied to field investigations for PCB-contaminated soils. The process is intended for site-specific sampling plans. Here the immunoassay would generally qualify as a Level 2 (field analysis) method, subject to confirmation by a Level 3 method (identification and quantification, i.e., EPA Methods 8080 or 8081) applied predominantly to positive results. We recommend that minimum quality control should include method blanks and duplicates at 5 percent, or one per batch or per matrix, whichever is the more frequent, in addition to the samples required for confirmation. The use of proficiency evaluation and spiked samples should depend on project-specific needs.

We recommend gas-chromatographic U.S. EPA Methods 8080 or 8081 for establishing or confirming the types and concentrations of Aroclor(s).

“Screening” and Preliminary Site Investigations–The immunoassay can assist in preliminary site investigations (“Phase I”), if there are compelling historical data to indicate the presence of PCBs. If used on samples of largely unknown composition, without prior characterization by an approved, fully qualitative and quantitative laboratory method, confirmatory analysis is needed for every positive immunoassay result. No negative determinations can be made without taking into account the specificity of the assay and its possible susceptibility to interferences and matrix effects. A margin of error (above the stated detection level) should be allowed for those PCBs that may show a lower response than those for which the assay has been calibrated.

In the absence of other regulations and guidelines, we recommend that assay results be confirmed in the following manner:

  1. For the delineation of PCB contamination in a coherent mass of soil, the required frequency of confirmation by an approved method resulting in identification and quantification is at least 10 percent of the samples testing positive at the target or action level applicable at the site. In the event that fewer than ten samples meet these criteria, at least one positive sample shall be confirmed. Higher rates of confirmation apply if there is a potential for chemical interferences.
  2. 10 to 20 percent of positive results below the target or action level should be confirmed by an approved, fully quantitative method, except that a higher rate of confirmation may be necessary if the results are to be used in health risk assessments.
  3. 5 to 10 percent of all negative results, but no less than one result from each site or suspect area, should be confirmed.

If appropriate protocols are followed, the immunoassay can be used to great advantage to classify contaminated soils as to low, medium, or high contamination and to determine which samples would provide the most information from laboratory analysis.

Site Investigations and Remedial Actions–Here the testing is expected to proceed under a site-specific Quality Assurance Project Plan (QAPP). Immunoassay and other field measurements will be “bracketed” in time and space by qualitative and fully quantitative analysis. Generally, a site is first characterized by the use of approved, fully qualitative and quantitative analytical methods as to the nature and level of contamination in key sampling locations and as to the presence of substances that may interfere the use of the immunoassay. After such initial characterization, the immunoassay can be used in the comprehensive mapping of the site with respect to identified contaminant(s) to which the immunoassay responds. The percentage of samples that would be confirmed by another approved, fully quantitative method would be as stipulated in the QAPP; the project manager could call for additional confirmatory testing if such a need is indicated in the course of the investigation. During site cleanup, the QAPP would provide for use of the immunoassay to monitor progress. Confirmatory laboratory testing would occur before a decision on site closure is made.

Regulatory Implications

This immunoassay has been accepted as a Draft Method by the U.S. EPA Office of Solid Waste (SW-846 Collection of Methods, Method 4020, Revision Draft 1, October 1992). The Department’s Certification is based on the technology’s performance and by itself does not change the regulatory status of PCB testing; it should, however, facilitate and encourage the acceptance of this technology where a project’s data quality objectives can be met by its use. To this end, the Department’s findings should contribute to a consideration of this technology in regulated activities, depending on each regulated program’s objectives and constraints.

State certification does not imply certification by the U.S. Government of use at federal superfund sites and other facilities under the jurisdiction of the U.S. Government for which state authorization for administrative oversight has not been granted. Under state implementation of the U.S. Resource Conservation and Recovery Act (RCRA), Treatment, Storage, and Disposal Facilities may contact state permitting agencies for use of the immunoassay for operational monitoring as part of a Waste Analysis Plan (WAP).

This Certification is issued as part of a pilot project to expedite the California Environmental Technology Certification Program. As a result, this Certification is subject to the conditions set out in the regulations to-be-developed, such as the duration of the Certification, the continued monitoring and oversight requirements, and the procedures for certification amendments, including decertification.

By accepting this Certification, the manufacturer assumes, for the duration of the Certification, responsibility for maintaining the quality of the manufactured materials and equipment at a level equal to or better than was provided to obtain this Certification and agrees to be subject to quality monitoring by the Department as required by the law under which this Certification is granted.

For more information, contact us at:

Department of Toxic Substances Control
Office of Pollution Prevention and Technology Development
P.O. Box 806
Sacramento, California 95812-0806
Phone: (916) 322-3670
Fax: (916) 327-4494

File last updated: October 31, 1996