The ENVIRHOM-Santé programme

Since 2003, IRSN has been developing a research programme known as ENVIRHOM-Santé geared towards determining the effects of low doses ¹ of ionising radiation on health. Its aim is to shed light on the nature and extent of non-cancerous biological effects triggered by chronic exposure to radionuclides - exposure that may continue throughout a person's life.

The studies carried out within the scope of this programme will initially generate numerous experimental data on the effects of chronic exposure on the body's major physiological functions (metabolism, cognitive functions, reproduction, immunity, etc.). Secondly, these data could consolidate and complete the radioprotection system developed to protect man against the effects of radionuclides in the event of chronic exposure to radionuclides via ingestion.

Finally, the long-term aim is to rely on this type of information in order to provide expert knowledge that can be used to assess health risks at both national and international level. In short, this experimental research programme has the following objectives :

1- To define the nature and extent of non-cancerous biological effects caused by chronic exposure to low concentrations of radionuclides ;
2- To determine the threshold(s) at which these biological responses occur ;
3- To specify whether the biological effects observed will have obvious harmful effects.

To respond to these objectives, the in-vivo experimental studies were based on the contamination of rodents (rats and mice) over a period of several months through the ingestion of drinking water containing concentrations of radionuclides similar to environmental levels. These contamination conditions aimed to reproduce potential exposure situations in electronuclear cycle installations in normal or post-accident scenarios.

Moreover, several contamination models were used in order to consider the heterogeneity of population possibly exposed at low environmental contamination levels: adult model (contamination from the adult stage), post-natal model (contamination from birth), in-utero model (onset of contamination during gestation), or pathological models (hypercholesterolaemia or Alzheimer’s disease for examples).

Several radionuclides were studied within the scope of this programme. To date, the studies have focused on uranium, either in its depleted, natural form, or enriched with uranium-235. Caesium 137 and strontium-90 were also investigated in order to evaluate the effects of chronic exposure in the case of a post-accident situation. These various situations of radionuclide exposure taken into account in the ENVIRHOM-Santé programme are indicated in the left column of the figure illustrated above.

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Links and references

1) Doctors refer to low doses as exposures below a hundred millisieverts (mSv) and very low doses as exposures of a few mSv, comparable to those to which human beings are naturally subjected.

2) La radioactivité dans mon environnement – Radioactvity in my environment – the site of the national network for measuring environmental radioactivity