Evaluation of Variability in Pesticide Concentrations in House Dust Samples Collected in Farmers’ Homes

U.S. Department of Health and Human Services (DHHS), National Institutes of Health (NIH), National Cancer Institute (NCI), Division of Cancer Epidemiology and Genetics (DCEG), Occupational and Environmental Epidemiology Branch (OEEB) intends to procure, on a sole source basis, service for the evaluation of variability in pesticide concentrations in house dust samples from Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238-5166, United States.The response close date of the notice for this requirement is in accordance with FAR 5.203(b). This acquisition will be processed under FAR Part 12 – Acquisition for Commercial Items and will be made pursuant to the authority in FAR Part 13.106-1(b)(1); and is exempt from the requirements of FAR Part 6. The North American Industry Classification System (NAICS) code is 541380 and the business size standard is $16.5 million.1.0 BACKGROUNDThe Occupational and Environmental Epidemiology Branch (OEEB) within the Division of

Cancer Epidemiology and Genetics (DCEG), National Cancer Institute (NCI), National Institutes of Health (NIH), conducts studies of cancer and environmental exposures to pesticides. Most epidemiologic studies of cancer risk from pesticide exposure have focused on occupational exposure pathways. However, non-occupational exposure pathways, such as take-home exposures from pesticide applications, agricultural drift from living near pesticide-treated fields, and residential use of pesticides in the home and yard, may also be important contributors for farm residents. One way to measure take home exposure from pesticide applications is to look at pesticide concentrations found in the household dust in homes in agricultural areas. Household dust has been used in many studies as a reliable surrogate for aggregate environmental pesticide exposures because of its ability to act as a stable reservoir that integrates pesticide exposures over time. For instance, previous OEEB investigations identified breakdown products of chlordane and Dichlorodiphenyltrichloroethane (DDT) (both Organochlorine [OC] insecticides) in household dust samples collected between 1999-2001, despite their ban in the 1970s and 1980s. Analyses to date have been based on the measurement of a single dust sample per home.OEEB investigators plan to evaluate the variability in levels of pesticide active ingredients in homes over time using house dust samples previously obtained from a subset of participants in the Biomarkers of Exposure and Effect in Agriculture (BEEA) Study, a sub-study conducted within the Agricultural Health Study (AHS), a cohort study of licensed pesticide applicators (mostly farmers) and their spouses in Iowa and North Carolina. This subset of participants from Iowa had between two and three dust samples collected in their homes at different times during the study.  These are referred to as repeated dust samples since they were collected in the same home but at different time periods. OEEB investigators are leveraging the availability of repeated dust collection conducted within a subset of BEEA participants to evaluate variability in pesticide exposure concentrations in house dust across a six to twelve-month time window. In addition to these repeated dust samples, additional dust samples from homes not in agricultural settings will be analyzed.2.0 OBJECTIVEThe primary objective of this project is to measure the concentrations of the pesticide active ingredients in a subset of 175 house dust samples previously collected from a sample of BEEA participants whose spouses were also enrolled in AHS and dust samples from homes not in agricultural settings. The Contractor shall aliquot the dust samples and analyze them for a panel of pesticides that represent currently used pesticides, as well as pesticides that have been banned, but that are environmentally persistent.3.0 SCOPEThe Contractor shall aliquot and measure pesticide active ingredient concentrations of 175 previously collected house dust samples. These dust samples were previously collected from the vacuum used most frequently in the home, passed through a 150 µm sieve, and stored at -12 oC. The Contractor shall aliquot, extract, and analyze the sieved dust samples for a panel of pesticides (see Attachment 1 - Table 1) that represent currently used pesticides (e.g., atrazine, chlorpyrifos, specific pyrethroids), as well as pesticides that have been banned, but that are environmentally persistent (e.g., chlordane, DDT, dieldrin, lindane), using the modified EPA Method 1699, which uses a high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) analysis.4.0 CONTRACT REQUIREMENTS/ AND PERSONNEL QUALIFICATIONS The Contractor shall measure the pesticide active ingredients listed in Attachment 1 - Table 1 below using the modified EPA Method 1699, which uses a high-resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) analysis. The NCI will select the 175 dust samples to be analyzed and provide the list of sample IDs to the Contractor’s sample processing department.The Contractor shall perform the following tasks for sample aliquoting, extraction, and analysis:4.1 The Contractor’s sample processing department shall aliquot the 175 previously processed and stored dust samples into vials with ≥ 0.5 gram of sieved dust and deliver the aliquoted dust samples to the Contractor’s chemical analysis group, along with any necessary documentation. The aliquoted dust samples shall be stored at -12 oC.4.2 The Contractor’s chemical analysis group shall extract and quantify the pesticide concentration in each 100 mg sieved dust sample using the modified EPA Method 1699, which uses a high-resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) analysis. Samples shall be extracted in batches of 20 field samples. Repeated dust samples from the same home must be extracted and analyzed in the same batch. Each batch shall also include a method blank, a laboratory control sample (LCS), and one matrix spike (MS)/matrix spike duplicate (MSD) from a field sample. Anhydrous sodium sulfate shall be used to simulate the dust matrix in both the method blank and LCS. Stable isotopically (13C or deuterium) labeled analogs of the pesticides shall be spiked into the dust samples and extracted with hexanes:dichloromethane (1:1) solvent system using Soxhlet extraction by EPA method 3540C. The organic extracts shall be concentrated and passed through Florisil cartridges. Extracts to be injected into the HRGC/HRMS shall be solvent exchanged to a final volume of 100 µL nonane using nitrogen evaporation. Immediately prior to analysis, a labeled injection internal analytical standard is added to each extract and a 1.0 µL aliquot of the extract is injected into the high-resolution gas chromatograph (HRGC). The analytes are separated by the HRGC and detected by a high-resolution power (6000 - 8000) mass spectrometer. For pesticides for which a labeled analog is available, the HRGC/HRMS shall be multi-point calibrated and the concentration determined using the isotope dilution technique. Pesticides for which a labeled analog is not available shall be determined using the internal standard technique. The need for a dilution analysis of a compound in a sample shall be dependent on two conditions – a) the concentration exceeds the calibration range, and b) the area for one or both monitored masses exceeds the area of the highest standard in the corresponding calibration curve. The Contractor shall provide a single dilution per sample when both conditions are met, with a maximum of 100x dilution to be performed.4.3 The Contractor shall assure the quality of the analysis through reproducible calibration and testing of the extraction, cleanup, and HRGC/HRMS systems that shall be based on the modified QC acceptance criteria based on guidelines in the EPA Method 1699 adapted to the dust matrix. Analytes such as Atrazine, Endosulfan I, Endosulfan II and Endosulfan sulfate have previously shown variable ion ratios at different concentrations in the standards. As such, these analytes shall be qualified with an “R” flag in the data reporting forms to indicate the potential occurrence. Limit of quantification (LOQ) for analytes of interest are expected to reach, or be lower, than the target LOQs listed in Table 1. The complexities of the dust matrix can cause some erratic performance of the HRGC/HRMS operating system, resulting in either suppression or enhancement of QC recoveries.  As a result, the QC limits established in Table 5 of EPA Method 1699 are considered advisory limits by the lab and may not necessarily require a re-extraction to be performed. The laboratory shall evaluate each exceedance on a case by case basis and shall determine whether an exceedance requires re-extraction and re-analysis based on the following: The laboratory shall analyze 4,4’-DDT for breakdown. If the breakdown exceeds 20%, the laboratory shall halt analysis and perform maintenance on the HRGC/HRMS system. Samples shall not be considered valid until this 20% is criteria is met.4.4 The Contractor shall analyze a method blank for each batch of 20 field samples. The method blank shall not contain target analytes above the minimum levels stated in table 1 of EPA Method 1699 or 5 times above the laboratory limit of quantitation (LOQ), whichever is larger. If an exceedance occurs, the laboratory shall evaluate and determine whether the exceedance requires re-extraction and re-analysis of the entire batch of samples. The laboratory shall analyze one LCS, and one MS/MSD, with each batch of 20 field samples. The recovery limits shall be within the limits stated in Table 5 of EPA Method 1699. Regarding the LCS, if an exceedance occurs, the laboratory shall evaluate on a case by case basis to determine whether re-extraction and re-analysis shall be required. The issues shall be noted in the case narrative.5.0 TYPE OF ORDERThis is a Firm-Fixed-Price purchase order for non-severable services. The services specified in each contract line item (CLIN) have been determined to be non-severable services - a specific undertaking or entire job with a defined end product of value to the Government.6.0 PERIOD OF PERFORMANCEThe anticipated period of performance shall be for 12 months from the date of award. 7.0 PLACE OF PERFORMANCEAll work shall be performed at the Contractor’s facility.8.0 REPORT(S)/DELIVERABLES AND DELIVERY SCHEDULEAll deliverables and results shall be submitted for inspection by the NCI Senior Investigator/Technical Point of Contact (TPOC), TBD at award, and returned for corrective action if necessary, within 14 business days of each data delivery. If no comments or requests for revisions are provided within 14 business days, the deliverables shall be considered acceptable. If an assay fails for one or more batches of samples (based on QC criteria described in section 4.4), the assay shall be repeated at no additional charge to NCI if sufficient dust is available or NCI is able to send additional samples. Corrected action is expected within 30 calendar days of the date of inspection.The Contractor shall store any remaining samples following the delivery of the final report and shall contact NCI prior to returning the samples to NCI. Deliverable #1 – Due within 60 business days of receiving sample IDs. Dust sample measurements and QC sample results (Following Steps 4.1-4.4) for the first batch of 20 dust samples delivered electronically as an Excel file. Sample results shall be reported on an as-received basis in unit of ng/g without dry weight adjustment. Any LCS exceedance shall be included in the case narrative along with a determination as to whether re-extraction and re-analysis shall be required.Deliverable #2 – Batch results, reported by batch. All results to be provided by July 15, 2021Dust sample measurements and QC sample results (Steps 4.1-4.4) for the remaining 8 batches of dust samples on a batch-by-batch basis. Sample results shall be reported on an as-received basis in unit of ng/g without dry weight adjustment. The sample measurement data and quality control results for each batch shall be delivered electronically as an Excel file. Any LCS exceedance shall be included in the case narrative along with a determination as to whether re-extraction and re-analysis shall be required.Deliverable #3 – Due by July 31, 2021Deliver a final report which describes the analytical method used, including details of the extraction method and GC/MS conditions, a summary of the quality control sample results including percent recoveries of spikes and coefficients of variation for replicate samples, and any problems encountered in the sample analyses. The electronic final report describing the analysis shall be delivered as a Word or PDF file.9.0       UNIQUE QUALIFICATIONS OF THE CONTRACTORUnder previous purchase orders, Southwest Research Institute (SwRI), in collaboration with NCI, DCEG, OEEB, has processed, aliquoted, extracted and/or analyzed dust samples from the BEEA study for a panel of pesticides that represent currently used pesticides, as well as pesticides that have been banned, but that are environmentally persistent.In Fiscal Year 2017 under purchase order HHSN261201700667P, SwRI conducted the same pesticide analyses specified under this acquisition on 150 dust samples from the BEEA study. In Fiscal Year 2018, the current batch of dust samples to be analyzed were processed and stored under contract HHSN261201700003I with American Type Culture Collection (ATCC), who sub-contracted the dust sample processing and storage to SwRI under task orders HHSN26100001 and HHSN26100002. To maintain comparability and retain the ability to pool sample results in future analyses, it is critical that the current analysis be conducted using the same analytical methods and quality control procedures. A change in vendor would provide results that are not scientifically comparable to previous findings and would disrupt the overall body of research.This notice is not a request for competitive quotations. However, if any interested party, especially a small business, believes it can meet the above requirement, it may submit a proposal or quote for the Government to consider. The response and any other information furnished must be in writing and must contain material in enough detail to allow NCI to determine if the party can perform the requirement. All responses and questions must be submitted via email to Adam Hernandez, Contracting Officer, at adam.hernandez@nih.gov. Responses are due no later than 9:00 A.M. EST Thursday, July 23, 2020 (07/23/2020). A determination by the Government not to compete this proposed requirement based upon responses to this notice is solely within the discretion of the Government. Information received will be considered solely for determining whether to conduct a competitive procurement. To receive an award, Contractors must be registered and have valid certification in the System for Award Management (SAM) through SAM.gov, and have Representations and Certifications filled out.Reference: 75N91020Q00130 on all correspondence.