Why it is hard to prove that heavy metals cause cancer in humans. The experts' explanations

Heavy metal contamination can cause cancer. At least that's what international studies say. Unfortunately, in Romania there is no way to determine to what extent these heavy metals cause ailments. There are no statistics, evidence, and to collect them, it takes a lot of time.

The central floatation is near Baia Mare, an area polluted with heavy metals PHOTO Go Green Resources

A non-governmental organization active in the field of environment, Go Green Resources, states that heavy metals (which are also in the deposits around Baia Mari and throughout the county) cause cancer.

Near Baia Mare and throughout the county there are those mine waste deposits abandoned after the closure of mining. Although some of them have been greened, another part of the tailings ponds continues to pollute with heavy metals.

In Romania, there are no statistics, no evidence to confirm the association of this disease with heavy metal poisoning, although we had heavy industry that caused a series of occupational diseases. But international studies published by scientific researchers have proven these associations.

Exposure to pathogens and the location of cancers

Thus, exposure to asbestos has been associated with cancer located in the pleura and peritoneum, lungs, larynx, gastrointestinal tract or kidneys. Cadmium exposure with lung cancer. Exposure to polycyclic aromatic hydrocarbons, silicon, or metal fumes found in metal smelters with lung cancer.

The data are in the Occupational Medicine Manual, from 2000, by the “Iuliu Hațieganu” University Medical Publishing House Cluj Napoca and signed by the authors Aristotel Ciocârla, Lucian Tefas and Marilena Petran.

Tăuții de Sus tailings pond PHOTO Go Green Resources

Tăuții de Sus tailings pond PHOTO Go Green Resources

In the 2009 edition, the data was more complete. Hydrocarbons to which those working in the aluminum industry are exposed have been associated with localized lung and bladder cancer. Exposure to silica has also been associated with lung cancer.

WHO data confirms

Studies over time have shown the negative impact of metals and their synergy, i.e. the cumulative effect by exacerbating the toxicity of one poison by another, also called the effect. Based on these studies, national and international regulations, toxicological data sheets, were created with the aim of limiting the consumption of certain products and restricting their release in nature“, explains university professor Dr. Ioan Bud, specialized in environmental and mining issues.


For example, the 2012 WHO report detailed the carcinogenic effect of crystalline silica on the lungs, stomach, intestines, esophagus and kidneys. In 2020, the Romanian Public Health Institute took over the information from the IARC (International agency for research on cancer) report regarding the cancer risk of crystalline silica”, says the university professor, criticizing the situation in Romania regarding the greening of former mining perimeters. “All studies and regulations are intended to warn and prevent medium and long-term impacts, but the situation in the former mining perimeters in Romania is outrageous in that there are increasingly large dispersions of toxic metals through mine waters and silica crystalline through the wind“, he also says, referring to the mining waste stored in the immediate vicinity of the city of Baia Mare.

We have no studies in this field

As for cancer, most cases are in the lungs. Of course, smoking also plays an important role, which makes lung cancer the most common worldwide, not just in Romania.

According to the deputy director of the Maramureș Public Health Directorate (DSP), Carmen Sima, screenings and modern equipment help in the early detection of this disease, but cannot make any direct association between an external factor and this disease.


Cancer is a chronic disease that has several risk factors, and these risk factors are very heterogeneous, multiple. From endogenous factors, racial or family factors, to exogenous factors, smoking, pollution, ultraviolet rays. And each location has, based on scientific bases and relevant population studies, a ranking of risk factors“, she explains.

Generic, pollution, sure is a risk factor. But how much it influences the occurrence of cancer, that is another topic of discussion. You cannot say that there is a direct causal relationship between pollution and cancer, but it acts as a risk factor along with other factors“, she adds.

Romania, in the penultimate place in terms of life expectancy

Approximately 95,000 Romanians were diagnosed with cancer in 2020. In most cases, it is located in the lungs in men (17%) and in the breast, in women (28%).

In Maramureș, the incidence in 2022 was 271 cases per 100,000 inhabitants, the figures being somewhat lower than in 2019, when the incidence was 294 cases per 100,000 inhabitants. The decline in cancer cases during the pandemic, however, had a different explanation, namely that people did not go to the doctor for fear of the virus, even if they had symptoms that would normally have sent them to the doctor.

Life expectancy in Romania is 74.2, in the penultimate place in Europe. In Norway it is 83.3 years.

The occupational medicine doctor, Dorin Triff, explained why we cannot now have a statistic or a study that can correlate this pollution with heavy metals and the number of cancer cases in Maramureș, where we had heavy industry and continue to have pollution with heavy metals.

There is research linking exposure to heavy metals and some forms of cancer. We have no such records. It is very difficult to make a direct connection between those who worked at Romplumb (former lead processing enterprise from Baia Mare, no) and the occurrence of cancer, because the evolution of cancer takes place over time“, he says.

How cancer starts

Also, the doctor explains, two factors are needed to trigger the disease. “Initially a mutation occurs. For example, smokers: they have some oxidizing agents and tars that cause mutations in the lung cells. But not only where they are absorbed, the body fights with them. A part is eliminated through urine, a part is deposited in the body. And there are mutations in their genetic code (of cells, no), which may or may not turn into cancer. One more cofactor is said to appear. We don't know what that cofactor is, it may be a second mutation. But they lie dormant, somehow instead of a normal nucleic DNA, when the time comes to express itself, it will have a predisposition to develop tumor cells“, he explains to everyone's understanding.

Then he gives the example of moles on the skin, which are considered precancerous formations, but which do not produce cancer except under certain conditions, so we live with them without affecting us in any way.

A person's sensitivity makes the difference

Moreover, he also shows that exposure to any risk factor will not have the same effect on everyone, and some more sensitive people will develop the disease, and others, more resistant, even if they have been exposed to the same risk factors, will remain healthy.

If the second cofactor appears that initiates the actual metaplastic process, i.e. carcinogenesis, from the moment tumor cell reproduction is triggered until it appears in clinical form, time intervals of the order of months or years pass. So from the moment the mutation appeared until the cancer appears, many years pass: 7, 8, 10, 30 or even 40 years. That is why it is very difficult to prove occupational cancer. You have to have proof that the platform was exposed, make the clinical connection“, he explains.