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riassunto
La definizione del nesso causale rappresenta spesso un problema di non agevole soluzione quando le patologie non hanno specifiche connotazioni eziologiche. Questo è certamente il caso delle malattie neoplastiche in lavoratori esposti ad agenti oncogeni in un contesto socio-sanitario nel quale il 25% delle persone vanno a morte per tale causa. Pertanto il contenzioso in questo particolare campo della medicina legale è in crescendo e sempre più si richiede di affidare la valutazione del legame causale a metodologie basate su criteri più obiettivi e scientifici rispetto a quello della presunzione d’origine. Nel caso delle radiazioni ionizzanti è stata introdotta la metodologia della probabilità causale (PC), che è un metodo per valutare la probabilità che collega un tumore a una esposizione. Essa si può ottenere partendo dalla definizione di eccesso di rischio relativo (R):
summary
The judgement of causation is often a very difficult task when the pathology das not have a specific aetiological connotation. This is the case when the causation is dealing with a neoplastic disease in a worker exposed to carcinogens in a community where 25% of peoples dies because of a cancer. Namely the litigation is increasing in this particular field of forensic medicine and a methodology based on criteria more objective and scientific than the “origin presumption” is always more required. As far as the ionising radiation, an aid in deciding the question of cause and effect between malignancy and a specific previous exposure is provided by the approach of Probability of Causation (PC). This is an epidemiologybased method of developing an estimate of the probability that a specified cancer and an exposure are linked together. The PC can be expressed in an equation based on the excess relative risk (R) due to radiation exposure: R PC = ----------------- 1 + R The value of R is “tailored” to the particular individual i.e. it is related to the size of the received dose, to the sex, to the age of exposure, to the time between exposure and the onset of disease, etc. The PC resulting value is a percentage indicating the likelihood of causative hypothesis, that is: it provides a science-based probability, rather than a proof of causation, related to the “strength” of the causal link between a previous exposure and a present neoplasia. This methodology is widely used in the U.S. where it was formerly proposed, it is used as a compensation agreement for nuclear industry in the U.K. and it is imported in our Country as a basis in deciding cancer causations in various operative contexts. Download testo completo (.doc 89 Kb)