# Protective Effects of Hydrogen against Irradiation.
> 放射線照射に対する水素の防護効果に関するレビュー


## Abstract

Radiation-induced lung injury progresses through an acute pneumonitis phase and a subsequent fibrotic phase, both driven by reactive oxygen species (ROS) including hydroxyl radicals and peroxynitrite. Molecular hydrogen (H2) rapidly crosses cell membranes and selectively neutralizes highly reactive oxidants such as •OH and ONOO-. Electron-spin resonance and fluorescent indicator analyses confirmed H2's capacity to eliminate •OH and reduce apoptotic damage in irradiated cultured lung epithelial cells. Animal studies using inhaled H2 gas for acute injury and H2-enriched water for chronic injury demonstrated radioprotective effects at both disease stages. Beyond direct ROS scavenging, H2 modulates gene expression to exert anti-inflammatory and anti-apoptotic actions while supporting energy metabolism. This review synthesizes evidence from cell-based and animal experiments supporting H2 as a candidate radioprotective agent, highlighting mechanistic advances and potential clinical relevance.

### Mechanism

H2 selectively scavenges hydroxyl radicals and peroxynitrite, and modulates gene expression to suppress inflammatory and apoptotic signaling while enhancing energy metabolism, thereby reducing radiation-induced oxidative tissue damage.

## Bibliographic

- **Authors**: Terasaki Y, Terasaki M, Shimizu A
- **Journal**: Curr Pharm Des
- **Year**: 2021
- **PMID**: [33463456](https://pubmed.ncbi.nlm.nih.gov/33463456/)
- **DOI**: [10.2174/1381612827666210119103545](https://doi.org/10.2174/1381612827666210119103545)
- **Study type**: review
- **Delivery route**: mixed routes
- **Effect reported**: not assessed

## Delivery context

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 33463456. https://h2-papers.org/en/papers/33463456
> **Source**: PubMed PMID [33463456](https://pubmed.ncbi.nlm.nih.gov/33463456/)