Experimental Pathology Laboratories, Inc.

Experimental Pathology Laboratories, Inc., a for-profit Subchapter S corporation headquartered in Sterling, Virginia, provides toxicology pathology, histology, and related laboratory research services to federal agencies as a prime contractor (99% of recent awards) across environmental health, pharmaceutical safety, and infectious disease research domains. The vendor competes full-and-open, without SBA set-asides, drawing on registered SAM presence since 2002 and a portfolio anchored to long-term federal research partnerships.

Customer concentration is extreme. The National Institute of Environmental Health Sciences dominates the dollar picture — 8 awards carrying $418.3 million in combined potential value, representing 94% of the vendor's total portfolio value. Within that total, two definitive contracts tower: a $49.8 million archives and repository management contract for the National Toxicology Program and NIEHS divisions awarded March 29, 2024 with completion by September 28, 2029, and a $25.3 million pathology research contract awarded July 18, 2026 with completion by January 17, 2037. Both are cost-plus-fixed-fee instruments with no set-aside. The National Cancer Institute and EPA Office of Research and Development round out the top tier by potential value, but EPA's 121 awards across multiple sub-offices (EPA at large, Office of Research and Development, Office of Air and Radiation) cluster into smaller purchase orders — the median EPA award sits well below the NIEHS anchors. The vendor has worked with 19 distinct federal agencies in total, including the Food and Drug Administration (73 awards, $3.4 million), CDC Pittsburgh (multiple purchase orders for small-animal pathology work), the Department of the Interior Fish and Wildlife Service, and the National Institute of Allergy and Infectious Diseases.

Work centers on histopathology and tissue analysis: H&E staining and sectioning of rodent tissues from chemical exposure studies (particularly PFAS, PFOA, and other perfluoroalkyl compound research); microscopic evaluation of tissue slides and preparation of pathology reports prepared by board-certified veterinary pathologists; archives and repository management; and support for small-animal efficacy studies. A $803,683 purchase order from NIAID awarded September 25, 2024 covers histopathology services for five prepared-slide efficacy studies and five fixed-tissue studies with options for additional work through September 24, 2027. Recent EPA purchases span histology of rodent tissues from PFAS studies ($28,290 and $25,221 purchase orders awarded October 24, 2024 and April 11, 2024), analysis of bronchial epithelial cells to detect chemical-induced morphological changes ($15,000 purchase order from EPA Office of Air and Radiation, October 25, 2024), and maternal and multi-generational PFOA exposure studies in rat models. The vendor also supports infectious disease research: a $50,660 NIAID purchase order from April 11, 2023 covered COVID-19 histology, immunohistochemistry, and pathology evaluation of hamster samples.

Activity has declined from a multi-decade baseline. The dataset shows 302 total awards spanning from 1981 to July 2026, but recent fiscal years reflect sharp contraction — seven awards in 2023, nine in 2024, one in 2025, and one in 2026. Only one award (combined potential value $804 thousand) completes within the next twenty-four months, limiting recompete exposure and suggesting the vendor's near-term pipeline is dependent on option exercises and task-order placement under existing indefinite-delivery contracts rather than new solicitations.

The vendor operates predominantly as a self-performing prime. SCI-reported invoicing of $21.1 million across fiscal years 2022–2024 shows a flat trajectory: $7.2 million (FY2022), $7 million (FY2023), $6.8 million (FY2024), with no FY2025 SCI activity yet reported. Workforce scaled at roughly 27 FTEs across those years, all self-delivered with zero subcontractor hours reported. Government-paid hourly rates on SCI contracts ranged from a 10th percentile of $109.21 per hour through a median of $118.27 per hour to a 90th percentile of $164.46 per hour, positioning EPL in the mid-range for specialized scientific labor. The vendor carries two sub-awards: one from Alpha Omega Biotechnology Services LLC (January 29, 2025) for radiological countermeasure product development support and archiving, and one from Leidos Biomedical Research Inc. (September 18, 2024) providing histology services including formalin fixation, paraffin embedding, H&E and immunohistochemical staining, and slide preservation for target characterization methods in cancer research. Parent vehicles include an EPA indefinite-delivery contract (68D99005) with 71 task orders, an FDA blanket purchase agreement (EP08D000730) with 33 task orders, and an HHS indefinite-delivery contract (HHSF223200830015I) with 28 task orders.

GROSS AND MICROSCOPIC PATHOLOGY, HISTOLOGY, ELECTRON MICROSCOPY, NECROPSY, STUDY MONITORING AND DATA AUDITING, PATHOLOGY QUALITY ASSURANCE AND PEER REVIEW, NEUROTOXICITY AND MORPHOMETRIC EVALUATION, ARCHIVE SERVICES, ADVISORY CONSULTATION IN ANATOMIC PATH