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  1. MCM Issues

Radiological and Nuclear Emergency Preparedness

Radiological and nuclear emergency preparedness topics including fast facts, medical countermeasures, the FDA's role, and guidance for industry

What’s new | Fast facts | FDA’s role | Medical countermeasures | Guidance for industry | Statements and updates | Additional resources | Contact FDA

The FDA and other agencies work hard every day to help prepare the nation for potential threats.

Everyone can be involved in disaster readiness by learning more about different types of emergencies, and creating an emergency supply kit and family emergency plan.

What's new

  • October 22, 2024: The FDA approved Zarxio (filgrastim-sndz) with an indication to increase survival of patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS) as could occur after a radiological or nuclear event. Zarxio is the ninth FDA-approved medical countermeasure and fifth biosimilar that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. For more information, see the product label (PDF, 829KB).

Fast facts about radiation emergencies In a radiation emergency, get inside, stay inside, and stay tuned. (Image: CDC)

From the Centers for Disease Control and Prevention (CDC)

  • During a radiation emergency, the most important steps you can take are to get inside or take shelter, stay inside to reduce your exposure to radiation, and stay tuned for further instructions on what to do.
  • Potassium iodide (KI) specifically blocks the uptake of radioactive iodine into the thyroid gland. Only take KI on the advice of a medical doctor, public health, or emergency management officials. Taking too much KI or taking KI when it is not recommended can have serious health risks.

Learn more about radiation emergencies

FDA's role

The FDA plays a critical role in protecting the United States from chemical, biological, radiological, nuclear, and emerging infectious disease threats.

The FDA’s roles in radiological and nuclear emergency preparedness and response include:

  • Facilitating the development and availability of medical countermeasures (MCMs) that can be used to diagnose, prevent, protect from, or treat conditions including those that result from radiation exposure. Also see Medical countermeasures below, and What are medical countermeasures?
  • Ensuring the safety and security of FDA-regulated products that may be impacted, or used to respond to public health emergencies. This includes ensuring food safety and medical product safety when manufacturing facilities are in an area impacted by a disaster.
  • Working with medical product sponsors to clarify regulatory and data requirements necessary to rapidly advance development of products essential to supporting response efforts. Also see Guidance for industry below
  • Protecting consumers against fraudulent products - Unfortunately, during emergency situations, fraudulent products claiming to prevent, treat or cure conditions associated with the emergency almost always appear for sale. The FDA monitors for fraudulent products and false product claims related to radiation and nuclear protection and takes appropriate action to protect consumers.
  • Conducting research to develop the tools, standards, and approaches to assess MCM safety, efficacy, quality, and performance and to help translate new technologies into innovative, safe, and effective MCMs. For example, FDA research includes an ongoing project to develop models of radiation damage in lung, gut, and bone marrow organs-on-chips and use these models to test candidate MCMs to treat such damage.
  • Leading the Advisory Team for the Environment, Food and Health, a federal interagency group of subject matter experts in radiological health and related matters.  Also see Advisory Team below

Medical countermeasures (MCMs)

Overview | About ARS | MCMs for H-ARS | Internal contamination

Overview

Exposure to radiation can affect the body in several ways. The adverse health effects from exposure to radiation range from mild, such as skin reddening, to serious, such as Acute Radiation Syndrome (ARS), cancer, and death. The adverse health effects of radiation exposure depend on the amount and type of radiation absorbed by the body. The duration of exposure (short vs. continuous) causes different adverse effects.

Exposure to radiation during a radiological or nuclear emergency can result from exposure to an external radiation source without any direct contact with radioactive materials, from direct contamination with radioactive materials, or from a combination of both. The type of exposure that would occur depends on the type of emergency.

  • External Radiation Source: Exposure can occur when all or part of the body absorbs radiation from an external radiation source without any direct contact with radiological materials. Exposure to an external source of radiation stops when a person leaves the area of the radiation source, the source is shielded, or the process causing exposure is halted.
  • Direct Contamination: Exposure also can occur when a person is contaminated with radioactive particles, which can be external and/or internal.
    • External contamination occurs when radioactive materials are deposited on external body parts such as skin, hair, and eyes, and clothes. External contamination stops when the radioactive material is removed by taking off contaminated clothing and completely washing off the contamination.
    • Internal contamination occurs when radioactive materials are taken into the body by inhalation or ingestion, or through open wounds. The deposition of radioisotopes in organs results in local exposure. Internal contamination stops when the radioactive material decays, is eliminated from the body via natural processes, or is removed by medical countermeasures.

Some medical countermeasures are available for treating the adverse health effects from exposure to radiation as well as for limiting or removing internal contamination to help prevent or minimize adverse health effects. In the event of a radiological or nuclear emergency, medical professionals will determine if MCMs are needed.

About Acute Radiation Syndrome (ARS)

Acute Radiation Syndrome is an acute illness caused by irradiation of the entire body (or most of the body) by a high dose of penetrating radiation in a short period of time, usually a matter of minutes.

Patients exposed to high doses of radiation will not be able to produce sufficient numbers of new white blood cells, red blood cells, and platelets, a condition called myelosuppression.

Two major clinical manifestations of radiation bone marrow injury are neutropenia (abnormally low level of neutrophils, a type of white blood cell) and thrombocytopenia (abnormally low level of platelets) that directly impact the survival of victims exposed to radiation. Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.

More about ARS:

MCMs to treat patients with radiation-induced myelosuppression following a radiological/nuclear incident (H-ARS)

Myelosuppression occurs when radiation damages the bone marrow. Suppression of the bone marrow blocks the production of blood cells. There are FDA-approved products that can help patients with H-ARS by facilitating recovery of bone marrow cells that develop into white blood cells, including neutrophils, which help fight off infections.

FDA-approved products that may be used to treat adult and pediatric patients acutely exposed to myelosuppressive doses of radiation, a condition known as Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS:

  • Neupogen (filgrastim) – approved March 2015 [more info; product label (PDF, 1.2 MB)]
  • Neulasta (pegfilgrastim) – approved November 2015 [product label (PDF, 1.7 MB)]
  • Leukine (sargramostim) – approved March 29, 2018 [more info (PDF, 299 KB); product label (PDF, 786 KB)]
  • NPLATE (romiplostim) – approved January 28, 2021 [product label (PDF, 684 KB)]
  • Udenyca (pegfilgrastim-cbqv) – approved November 28, 2022 [product label (PDF, 460 KB)]; single-dose prefilled auto-injector presentation approved March 3, 2023 [product label (PDF, 1.3 MB)]
  • Stimufend (pegfilgrastim-fpgk) - approved September 29, 2023 [product label]
  • Ziextenzo (pegfilgrastim-bmez) – approved February 2024 [product label (PDF, 424 KB)]
  • Nypozi (filgrastim-txid) - approved June 2024 [product label (PDF, 2.4 MB)]
  • Zarxio (filgrastim-sndz) - approved October 2024 [product label (PDF 829KB)]

Internal contamination

Internal contamination with radioisotopes occurs when radioactive materials are taken into the body by inhalation or ingestion, or through open wounds, and are transported into cells, tissues, and organs specific for the radioisotope, (e.g. lungs, kidneys, bone marrow) resulting in local exposure at that site of incorporation. Internal contamination stops when the radioactive material decays, is flushed from the body via natural processes, or is removed by MCMs called decorporation agents.

Decorporation agents

FDA-approved decorporation agents that may be used in radiation emergencies, to limit damage from internal contamination with specific isotopes, include:

Thyroid blocking agent
  • Potassium iodide (KI) blocks the uptake of radioactive iodine into the thyroid gland

Also see: Radiation Emergencies (additional information about MCMs from FDA), and Medical Countermeasures (Treatments) for Radiation Exposure and Contamination, from CDC

Guidance for industry

The FDA works with medical product sponsors to clarify regulatory and data requirements necessary to move investigational products forward in development as quickly as possible.

FDA guidance documents related to radiation and nuclear preparedness include:

To learn more about guidance, or view more FDA guidance documents, see Search for FDA Guidance Documents

Statements and updates

  • June 28, 2024: The FDA approved Nypozi (filgrastim-txid) with an indication to increase survival of patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS) as could occur after a radiological or nuclear event. Nypozi is the eighth FDA-approved medical countermeasure and fourth biosimilar that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. For more information, see the product label (PDF, 2.4 MB).

  • February 28, 2024: The FDA approved a new indication for Ziextenzo (pegfilgrastim-bmez) to increase survival of patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS) as could occur after a radiological or nuclear event. Ziextenzo is the seventh FDA-approved medical countermeasure and third biosimilar that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. For more information, see the product label (PDF, 424 KB).

  • September 29, 2023: The FDA approved a new indication for Stimufend (pegfilgrastim-fpgk) to increase survival of adult and pediatric patients acutely exposed to myelosuppressive doses of radiation (H-ARS) as could occur after a radiological or nuclear event. Stimufend is the sixth FDA-approved medical countermeasure and second biosimilar that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. For more information, see the product label (PDF, 428 KB). 

  • April 19, 2023: The FDA announced availability of a draft guidance for industry, Acute Radiation Syndrome: Developing Drugs for Prevention and Treatment. The purpose of this draft guidance is to provide information and recommendations to assist sponsors and other interested parties in the development of drugs to prevent or treat acute radiation syndrome (ARS) caused by exposure to ionizing radiation from accidental or deliberate events. Generally, drugs developed for such indications will require approval under the regulations commonly referred to as the Animal Rule. Submit comments by July 19, 2023.
  • March 3, 2023: The FDA approved (PDF, 296 KB) a new single-dose prefilled auto-injector presentation of Udenyca (pegfilgrastim-cbqv) to increase survival of adult and pediatric patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS) as could occur after a radiological or nuclear event. For more information, see the product label (PDF, 1.3 MB).
  • November 28, 2022: The FDA approved a new indication (PDF, 244 KB) for Udenyca (pegfilgrastim-cbqv) to increase survival of adult and pediatric patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS) as could occur after a radiological or nuclear event. Udenyca is the fifth FDA-approved medical countermeasure and first biosimilar that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. For more information, see the product label (PDF, 460 KB). 
  • September 21, 2021: The FDA deactivated Import Alert #99-33 (IA) that has targeted certain food products from Japanese prefectures (Japan’s equivalent of a U.S. state) located near the damaged Fukushima Daiichi nuclear power plant since 2011. FDA will continue communication and collaboration with the Government of Japan to monitor and ensure the safety of food products exported from Japan to the U.S., as it has since the days following the 2011 disaster.
  • April 14, 2021: The FDA updated the page FDA Response to the Fukushima Daiichi Nuclear Power Facility Incident with new information after the Government of Japan announced it has decided to discharge into the ocean the wastewater that is currently being stored on site at the Fukushima Daiichi nuclear power plant.
  • January 28, 2021: The FDA approved a treatment to increase survival in adults and pediatric patients (including term neonates) acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome [HS-ARS]). For more information about this treatment, please see the NPLATE (romiplostim) product label (PDF, 684 KB).
  • December 2, 2019: Regulatory science update - The FDA awarded a contract in September 2019 to the Wyss Institute for Biologically Inspired Engineering at Harvard University to advance the use of human organs-on-chips for medical countermeasure (MCM) development by demonstrating biomimicry and defining critical qualification criteria, helping to reduce the reliance on testing in animals. This work builds on past FDA-funded work that led to the development of human models of acute radiation syndrome (ARS) in bone marrow, intestine, and lung organs-on-chips and the application of these tools to the evaluation of ARS MCMs.
  • March 29, 2018: The FDA approved a new indication for Leukine (sargramostim) to increase survival of adult and pediatric patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS) as could occur after a radiological or nuclear event. Leukine is the third FDA-approved medical countermeasure that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. See Medical countermeasures for more information

Advisory Team

The Advisory Team enhances preparedness and response capabilities by providing protective action recommendations to government officials following accidents or incidents that result in the release of radioactive material to the environment. The Environmental Protection Agency (EPA), U.S. Department of Agriculture (USDA), and CDC also participate on this team, which has been active since 1996 and conducts regular national radiological emergency response exercises.

The Advisory Team deploys some of its members to the site of the incident, where they integrate into the Incident Command structure, typically at the State Emergency Operations Center and the Joint Field Office. Other members provide support from their headquarters locations to provide reachback for the field team, and to provide guidance to Incident Command while the field team is in transit to the incident site.

The Advisory Team provides guidance on a wide variety of topics consistent with the missions of the participating agencies. This includes recommendations on drinking water safety, agricultural contamination, human exposure, KI usage, population monitoring, long term recovery and many other issues.

Food safety

To protect the public from foods that may be contaminated with radioactive material as the result of a radiological or nuclear incident, the FDA implemented the August 1998 guidance Accidental Radioactive Contamination of Human Food and Animal Feeds: Recommendations for State and Local Agencies (PDF, 231 KB).

Food contamination issues (also referred to as the ingestion pathway) play a prominent role in any discussion of large-scale radiological or nuclear emergencies.  The Advisory Team plays a significant role in providing guidance to decision-makers on assessments of food contamination and protective actions that may be taken to avoid excessive exposure to the public.

The FDA Winchester Engineering and Analytical Center (WEAC) serves as the lead for the radiological component of the Food Emergency Response Network (FERN) which is a consortium of federal and state laboratories having demonstrated capabilities for radiological analysis of foods to assess the level of contamination from rad/nuc emergencies.  In a large-scale event, WEAC would coordinate the processing of food samples across the network, with WEAC being the primary lab, and other laboratories providing surge capacity. The results of these analyses can be provided to local, state, and federal officials to help determine any actions that may be needed to protect the food supply.

Additional resources

Consumers | Healthcare providers | Governments (SLTT) | Communicators | Additional FDA emergency response info

For consumers

For healthcare providers / public health professionals / responders

For state, local, territorial, and tribal (SLTT) governments

For communicators

Additional FDA emergency response information

Archived information

Archived information is provided for reference. Information in this section may be out-of-date.

Contact FDA

Consumer inquiries
OCOD@fda.hhs.gov, 888-INFO-FDA

Media inquiries
fdaoma@fda.hhs.gov, 301-796-4540

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