EPA Superfund Site

NATIONAL SEMICONDUCTOR CORP.

CA | EPA ID CAD041472986

About this site’s exposure pathways: As of December 2024, the National Semiconductor Corp. Superfund site is considered “Insufficient Data to make a Human Exposure evaluation” (HEID). National Semiconductor Corp. Superfund site was finalized on the NPL on 07/22/1987, and an evaluation of the human health exposure risks is ongoing.

EPA uses this Human Exposure status when there is insufficient data/evidence to determine whether actual or reasonably anticipated human exposures are occurring, and/or whether those exposures are above acceptable risk-based levels. The planned activities to collect sufficient information to make a human exposure evaluation is vapor intrusion (VI) investigation completion and evaluation. Until this investigation has been completed it is not possible to determine whether the site is protective of human health. Mitigation activities are completed as necessary, including ventilation upgrades, pathway sealing, installation of active depressurization systems, and confirmatory sampling and long-term maintenance plans to confirm the continued effectiveness of the mitigation measures.

EPA currently anticipates that there will be sufficient data to make a Human Exposure determination by 2026 because the VI investigation evaluation will be completed by then.