Penalized linear discriminant analysis and Discrete AdaBoost to distinguish human hair metal profiles: The case of adolescents residing near Mt. Etna.

The research focus of the present paper was twofold. First, we tried to document that human intake of trace elements is influenced by geological factors of the place of residence. Second, we showed that the elemental composition of human hair is a useful screening tool for assessing people's exposure to potentially toxic substances. For this purpose, we used samples of human hair from adolescents and applied two robust statistical approaches. Samples from two distinct geological and environmental sites were collected: the first one was characterized by the presence of the active volcano Mt. Etna (ETNA group) and the second one lithologically made up of sedimentary rocks (SIC group). Chemical data were statistically processed by Penalized Linear Discriminant Analysis (pLDA) and Discrete AdaBoost (DAB). The separation between the two groups turned out well, with few overlaps accounting for less than 5%. The chemical variables that better distinguished ETNA group from SIC group were As, Cd, Co, Li, Mo, Rb, Sr, U and V. Both pLDA and DAB allowed us to characterize the elements most closely related to the volcanic contribution (As, U and V) and those (Cd, Co, Li, Mo, Rb and Sr) prevalently influenced by the geology of the area where SIC samples were collected. We conclude that the geological characteristics of the area of residence constitute a key factor in influencing the potential exposure to trace elements. Hair analysis coupled with robust statistical methods can be effectively used as a screening procedure to identify areas at great environmental risk.

[Etiological hypothesis on five cases of elastofibroma dorsi]. / Ipotesi eziologica su cinque casi di elastofibroma dorsi.

Elastofibroma dorsi is a rare benign lesion of the soft tissue of the thoracic wall, usually located in the subscapular region. It occurs mostly in elderly women patients. This lesion usually arises in right region but it can also be bilateral. Even if the pathogenesis is still unknown, it is considered that "rubbing" of the scapula against the thorax wall could determine growth of the elastofibroma. The differential diagnosis from sarcoma is required but the typical localization and the MRI suggest the diagnosis which should be confirm with the histological exam. The Authors present their experience on five patients, with a median age of 64, affected by elastofibroma dorsi. In two cases, a builder and an obstetrician, the lesion was bilateral; in the other three cases, two teachers and a notary, the lesion are right-sided. A thorax computed tomography (CT) revealed a lesion with heterogeneous density, and the magnetic resonance imaging (MRI) , shows intralesional areas of medium and high intensity signals in the tissue with low intensity in both T12 and T2-sequences. The patient underwent surgery and diagnosis was confirmed by the histological exam. Prevalence of the right localization reported in literature, the correlation between the job of the patients and the lesion localization, more evident in the women, confirmed, according to the other Authors, the etiological hypothesis which considers the lesion as a proliferative response of the connective tissue to the repeated mechanical stress which excessive elastic fibrollogenesis probably due to genetic predisposition.