Marie & Pierre Curie's belongings: Even after more than 120 years, why everything Nobel Prize-winning couple touched is still kept in lead-lined boxes

More than a century after Marie Curie and her husband Pierre Curie isolated radium, the notebooks she used during their groundbreaking research remain radioactive. Stored in lead-lined boxes at the Bibliothèque nationale de France, the manuscripts can only be viewed by researchers wearing protective equipment after signing a liability waiver. The reason lies in the extraordinary properties of radium-226, an element with a half-life of around 1,600 years, meaning the contamination left on the pages has barely diminished since the early 1900s.

Why are Marie Curie's notebooks still radioactive?

Marie Curie's notebooks are contaminated with radium-226, a radioactive element that she and Pierre Curie isolated after years of painstaking research.

According to the International Atomic Energy Agency (IAEA), radium-226 has a half-life of approximately 1,600 years. A half-life is the time it takes for half of the radioactive atoms in a substance to decay into a more stable form.


Because only a small fraction of that time has passed since Curie handled the notebooks between 1899 and 1902, they remain measurably radioactive today.

As a result, the Bibliothèque nationale de France stores the manuscripts in lead-lined containers, and researchers must wear protective equipment before examining them.

Marie Curie and Pierre Curie spent years isolating radium

The discovery of radium was far from straightforward. Working in an abandoned shed on Rue Lhomond in Paris, Marie and Pierre Curie processed nearly eight tonnes of pitchblende, a uranium-rich mineral, over almost four years.

Their laboratory lacked proper ventilation, temperature control or modern safety equipment.

Marie later recalled the physically demanding process: "I had to spend a whole day mixing a boiling mass with a heavy iron rod nearly as large as myself. I would be broken with fatigue at the day's end."

Through thousands of rounds of chemical separation and crystallisation, the couple eventually isolated just one-tenth of a gram of radium chloride.

The makeshift laboratory where history was made

The Curies carried out their research in what was once an abandoned dissecting room behind the Municipal School of Industrial Physics and Chemistry.

The building had a leaking glass roof, no fume extraction systems and poor insulation.

During summers, temperatures inside became unbearable, while winters left the researchers with numb fingers as they stirred boiling chemical mixtures.

Despite the difficult conditions, the Curies believed pitchblende contained an unknown radioactive element because it emitted more radiation than uranium alone could explain.

That observation eventually led to the discovery of polonium and radium.

The hidden dangers of radium were not fully understood

Although the Curies recognised that radium could burn skin and damage tissue, scientists at the time did not fully understand the long-term health risks of ionising radiation.

Pierre Curie even deliberately placed radium against his arm to observe the effects of radiation burns.

Marie frequently carried radium samples in her laboratory and kept some in desk drawers at home.

The couple famously admired the glowing blue light emitted by radium.

They later described those evenings as: "The best and happiest of our lives."

However, prolonged exposure eventually came at a devastating cost.

Marie Curie died in 1934, aged 66, from aplastic anaemia, a disease widely linked to long-term radiation exposure. Her daughter, Irène Joliot-Curie, who also worked with radioactive materials, later died from leukaemia.

Why Marie Curie's belongings are still protected today

The radioactive contamination extends well beyond Curie's notebooks. According to the Musée Curie in Paris, several of her personal belongings, including laboratory notebooks, furniture, cookbooks and other possessions, continue to emit measurable radiation and are carefully stored.

When Marie Curie's remains were transferred to the Panthéon in Paris in 1995, officials placed her coffin inside a lead lining because her remains still emitted detectable radiation.

Researchers visiting archives containing her work continue to follow strict safety procedures.

Marie Curie changed science forever

Marie Curie's discoveries transformed modern physics, chemistry and medicine. She coined the term "radioactivity" and became the first woman to receive a Nobel Prize.

In 1903, she shared the Nobel Prize in Physics with Pierre Curie and Henri Becquerel for their pioneering work on radioactivity.

She made history again in 1911, winning the Nobel Prize in Chemistry for isolating radium and discovering polonium.

She remains the only person to have received Nobel Prizes in two different scientific disciplines.

The Institut Curie, founded from her pioneering work, continues to be one of the world's leading centres for cancer research.

Scientific studies confirm the long-lasting nature of radium

Studies by organisations including the International Atomic Energy Agency (IAEA) and the US Centers for Disease Control and Prevention (CDC) explain why radium contamination persists for centuries.

Radium-226 continuously emits ionising radiation while slowly decaying into other radioactive elements, including radon gas.

Because only around 120 years have passed since Marie Curie handled her notebooks, scientists estimate that well over 90 per cent of the original radioactivity remains.

This explains why the manuscripts continue to require special handling more than a century after they were written.

Marie Curie's notebooks remain one of science's most extraordinary artefacts

Few scientific documents illustrate the lasting impact of discovery quite like Marie Curie's notebooks.

They preserve not only the handwritten record of one of history's greatest scientific breakthroughs but also the physical traces of the element that transformed modern science.

More than 120 years later, anyone wishing to read those pages must still take precautions against the invisible force that changed the world.


Inputs from TOI