# Risks of radiation exposure to old military compasses with radioluminescent markings

## TL;DR

Old military compasses with radium-based paint can expose users to harmful radiation, requiring proper handling and storage to avoid health risks.

## Contribution

This study quantifies radiation exposure from historical radioluminescent compasses and highlights safety concerns for collectors and the public.

## Key findings

- Radium presence was confirmed in three historical compass models using gamma spectrometry.
- Ambient dose equivalent rates were measured to assess radiation exposure during handling and storage.
- Radiation doses may exceed safety limits for the general public under certain conditions.

## Abstract

This study investigates the radiological safety of handling old radioluminescent military compasses whose markings are coated with radium-based luminous paint, historically used to ensure better visibility in dim or night-time conditions until the 1960s, when its use was discontinued and eventually banned due to the mounting evidence of its harmful health effects, including the increased risk of cancer. Using gamma spectrometry, we confirmed radium presence in three historical compass models, namely M.49, M.53 S1, and the small Bézard model. We also measured ambient dose equivalent rates to assess ionising radiation exposure at the usual distances from the source during routine handling or long-term storage of these devices. Our findings indicate that, under certain conditions, radiation doses may exceed the recommended safety limits for general public and underscore the importance of raising awareness about potential radiological risks associated with antique navigation instruments. Our study points to the need for appropriate safety protocols, handling procedures, and storage conditions to minimise these risks among collectors of military memorabilia as well as the general public in line with the ALARA principle.