October the 8th, 2026 – Radioactive strontium found in the soil in the Gospić area has jumped by an extremely concerning 961 percent, but what is being done about it?

In the surface layer of soil at the measuring point in Gospić last year, an almost 11 times higher concentration of radioactive strontium-90 per square metre was recorded than in 2023, according to the regular annual reports of the Zagreb Institute for Medical Research and Occupational Health (IMI), published on the Ministry of the Interior’s website. Slobodan Mufic reports for Index that the published activity per square metre rose from 24.5 to 260 becquerels, or by as much as 961 percent. The concentration of strontium-90 (Sr-90) per kilogram of material at the Gospić measuring point also rose drastically: from 0.605 becquerels per kilogram in 2023 to 4.08 becquerels in 2025, or almost seven times.

has radioactive contamination occurred?

It should be emphasised immediately that there is no evidence pointing to a connection between strontium-90 and the illegal waste at the former PPK Velebit in Bilajska Street in Gospić, nor does this change in itself mean that radioactive contamination has occurred or that the health of residents is endangered. The measuring point in Gospić is located about 7.6 kilometres southwest of PPK Velebit and so far there is no evidence that would confirm a link between the two locations.

Strontium-90 is a radioactive form of the chemical element of the same name, a silvery-white metal. This means that its atomic nucleus decays over time and in doing so releases radiation that can damage living cells. Strontium-90 does not exist originally in nature, but is created by the fission of atomic nuclei, for example in nuclear reactors and during nuclear weapons explosions. “All Sr-90 in the environment on Croatian territory is a consequence of the Chernobyl disaster back in 1986. Sr-90 has a half-life of 28.8 years. After the half-life has elapsed, the activity and quantity of the radionuclide fall to half of the initial amount, so it is not surprising that Sr-90 is still present in Croatia – there is still approximately 38% of the quantity that was initially deposited.

This radionuclide is anthropogenic; it is created by the fission of uranium-235. Sr-90 entered the environment from the atmosphere, via the radioactive cloud, and accumulated in the surface layer. Therefore it is not surprising that it is most present there, because it spreads into deeper layers by the slow process of diffusion,” states the response of IMI’s Radiation Protection Department.

Gospić is the only area to record an increase since 2023…

The origin of strontium-90 has been explained, but there is no adequate answer as to why its concentration on the surface has enormously increased only in Gospić over the last three years. Among the five measuring locations we compared, Gospić had the lowest surface value of strontium-90 in 2023, and two years later the highest. While between 2023 and 2025 that value fell in Zadar, Osijek, Buzet/Pula and Opuzen, in Zagreb it rose by approximately 92 percent, and in Gospić by 961 percent. Becquerel per kilogram (Bq/kg) indicates how much radioactivity is concentrated in a kilogram of soil, while becquerel per square metre (Bq/m²) indicates how much total radioactivity of Sr-90 exists under one square metre of surface. Since Bq/kg can fluctuate considerably if the sample one year is a little lighter, denser or richer in organic matter, Bq/m² is to some extent a better indicator.

If there is no new input or soil erosion, the total Sr-90 expressed in Bq/m² should mostly gradually decrease due to radioactive decay, and not increase as in the Gospić case. It should also be added that in the deeper layers of the earth, below the surface five centimetres, the opposite occurred: the concentration of Sr-90 is strongly declining.

The Radiation Protection Department offered this answer to the question about the professional interpretation of the increase in Sr-90 concentration: “In Gospić soil Sr-90 is continuously monitored, with a break in the period 2014–2022. It was reintroduced into the environmental radioactivity monitoring programme in the Republic of Croatia in 2023 and continues to be monitored. The measured values varied and no year-on-year upward trend was observed. For example, in 2003 440 Bq/m² was measured, in 2004 280 Bq/m², in 2005 180 Bq/m², and in 2007 270 Bq/m². In order to establish whether the increase in the period 2023–2025 represents the beginning of an upward trend, more time needs to pass.” The last measured and published value of 260 Bq/m² is not in itself a historical maximum in Gospić, but such a sudden jump from 24.5 to 260 in only two years is shocking. An additional problem is that IMI did not carry out measurements in Gospić from 2007 to 2023.

Although IMI wrote in its 2024 report that only in Gospić “is the activity concentration of Sr-90 is several times higher than last year’s”, there’s no data that because of this obvious anomaly, which was repeated in 2025, a new control measurement was proposed or requested.

nobody requested or paid for additional monitoring

“Sampling within the framework of environmental radioactivity monitoring is carried out in agreement with the client of the work, in this case the Ministry of the Interior. IMI cannot itself define where and how often sampling will take place. We have not received a request from the client for additional or extraordinary sampling in Gospić.

Every year, sampling for the following year is agreed with the Ministry of the Interior. We may propose the mentioned, but the Ministry of the Interior will decide. That is open for now. It should be emphasised that it is possible to carry out detailed research outside the regular monitoring; we have often done that so far. Someone has to order and pay for it,” the Radiation Protection Department replied to the question whether it would recommend to the Ministry of the Interior more sampling points, more frequent sampling, analysis of water, vegetation, food or sediment. An interpretation of this sensitive issue was sought from a renowned Croatian scientific institution, without revealing what it was about. A radioactivity expert, who requested not to be named, answered the question whether a multiple increase in the concentration of strontium-90 on the soil is possible without a new source of contamination: “NO. That would be a perpetual motion machine.”

When we explained to him what it was actually about, he said that the only reasonable explanation could be deficient sampling, or inadequate laboratory analysis: “Measuring low activities is very delicate and it can happen that laboratories have different instrumentation, so measurements near the detection limits can deviate significantly. This is especially the case with measuring Sr-90, which is quite complicated. The analysis takes about three weeks.”

no answers have come from institutions about potential health risks…

From the existing data, it is not possible to draw a concrete and reliable conclusion about the impact of the strontium-90 concentration on people in Gospić. The surface increase refers to activity per square metre of soil, and not to the radiation dose received by citizens. To assess the health risk it is necessary to determine what dose residents receive due to radiation from the environment and the possible intake of radioactive substances through food, water and inhalation of particles. The soil finding alone is not sufficient either for the claim that there is a danger to health or for the claim that it is completely ruled out.

Interestingly, the Radiation Protection Department did not want to comment on the possible danger to human health: “The assessment of the threat from a particular radionuclide, which includes the ways of its propagation through the environment and the food chain, is not part of our contract in monitoring environmental radioactivity. That topic is quite complex and requires an interdisciplinary approach that would consider all relevant aspects.”

There was no concrete answer from the Croatian Institute of Public Health to Index’s inquiry. Unofficially we received the message: “We do not deal with that.” And the Ministry of the Interior’s Civil Protection Directorate completely ignored several inquiries on this topic; that is, even after two weeks no answer arrived. The key question in this story is not the concentration of strontium-90 itself and its possible impact on human health, but the inertia and disinterest of the competent institutions in reacting and additionally checking findings that clearly deviate from trends and expectations. Just as in the case of the illegal waste at Bilajska 50.


 


Subscribe to our newsletter

the fields marked with * are required