Izlaganje sa skupa
Occupation and Environment and Cancer Studies in Croatia
Marko Šarić
; Institut za medicinska istraživanja i medicinu rada
Sažetak
According to data of the International Agency for Research on Cancer there are 55 confirmed carcinogenic environmental agents (chemicals), 45 agents show sufficient evidence to be considered as probable carcinogens, and 191 are possibly carcinogenic for humans. Considering the fact that there are 60,000– 70,000 agents currently in use, only a small portion of them is likely to be carcinogenic. In a recently published estimation referred to in this paper, smoking – including passive smoking – and diet are considered to account for almost two thirds of all cancer deaths, but are among the most correctable. Radiation causes perhaps 2% of cancers. Most fatalities result from exposure to natural sources of radiation such as the sun’s ultraviolet rays, and can be attributed to skin melanoma. Environmental pollutants make about 2% and occupation about 5% of cancer causes. In industrialised countries the cancer risk from occupational exposure has been much reduced over the past several decades. In developing countries occupation still carries a substantial risk of cancer. Furthermore, the role of infectious agents as potential causes of cancer seem to be more important in these countries than in developed countries. The great majority of cancers occur in the epithelial tissue, which indicates the interaction between host factors (such as genetic endowment, health, and nutritional status) and environment. Although recent studies definitely support the role of genetic factors in the aetiology of cancer, these factors alone are believed to be responsible for only a small fraction of cancers. Before exerting their effects many environmentally persistent carcinogens must undergo biotransformation to reactive intermediates or otherwise be activated metabolically. The stages of cancer development with average latencies of 25 years are generally considered to include initiation of target (somatic) cells, promotion of these cells, and progression and further growth. However, in theory, a single exposure can initiate carcinogenesis, as has been experimentally demonstrated with some compounds such as ethylen oxide. There are two major sources of information from which to estimate human carcinogenicity of chemicals: a) controlled laboratory studies with experimental animals and various in vitro systems and b) epidemiological studies, usually based on workplace exposure and occasionally based on studies of general population. In our country, studies on the occurrence of occupationally and/or environmentally induced cancers are rather scarce. Skin cancer was studied in subjects exposed to sun on the island of Vis and [olta in the Croatian Adriatic. The first cases of angiosarcoma of the liver in workers employed in the PVC production were diagnosed in 19 75. The incidence of malignant tumours of the lung and bronchus and of cy tologically confirmed primary tumours of the liver was studied in the Split area with a polyvinyl industry. The incidence of malignant tumours of the lung and peritoneum was studied in the Croatian coastal region with an asbestos processing plant. A similar retrospective study on the incidence of tumours which can be related to ambiental exposure to asbestos included an area of Split with an asbestos–cement plant. In addition to those types of studies on the correlation between exposure and cancer incidence in selected occupational groups and general population, a case control study was also performed in two areas of Croatia with different risk for gastric cancer. The paper addresses difficulties in identifying low relative risk for common cancer such as lung cancer. Lifestyle factors such as smoking and alcohol consumption, which increase risk for certain cancer types, can enhance or swamp other exposures and make their delineation all the more difficult.
Ključne riječi
causes of malignoma; sites; interactions in carcinogenesis; quality assessment of carcinogenesis
Hrčak ID:
65640
URI
Datum izdavanja:
26.7.2000.
Posjeta: 1.752 *