LIST DO REDAKCJI
Ostatnie badania nad neurotoksycznością ołowiu. Dawno znany Metal – nowe zagadnienia
 
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Children’s Hospital Boston Harvard Medical School Harvard School of Public Health
AUTOR DO KORESPONDENCJI
David C. Bellinger   

Children’s Hospital Boston Harvard Medical School Harvard School of Public Health
 
Med Środow. 2011;14(3):7–12
SŁOWA KLUCZOWE
STRESZCZENIE ARTYKUŁU
Wiele razy w historii toksykologii ołowiu przeważał pogląd, że problem ten został rozwiązany a ekspozycja na ołów nie jest już poważnym zagadnieniem zdrowia publicznego. Za każdym razem dalsze dodatkowe badania wykazywały, że taki pogląd jest przedwczesny. Wostatniej dekadzie nadzwyczajnie duża liczba nowych badań ukazała, że „problem” pozostaje i że jego rozmiary są tak szerokie jak nigdy przedtem tego nie spodziewano się. Inteligencja dzieci tradycjonalnie była uważana za najbardziej czuły końcowy wskaźnik i była używana jako podstawa dla oceny ryzyka i ustalania standardów. Dla IQ związek dawka–skutek okazał się być supra-linearnym z większymi deficytami przez zwiększenie μg/L ołowiu poniżej aniżeli powyżej stężenia 100 μg/L w krwi. Ostatnie badania wykazały, że większa ekspozycja na ołów we wczesnym okresie dzieciństwa jest również związana z szeroką różnorodnością występowania innych następstw, które są skojarzone ewidentnie na poziomie biomarkerów porównywalnie do tych, przy których obserwuje się deficyty IQ.Wśród tych końcowych następstw wymienia się gorszą zdolność do uczenia się na poziomie akademickim, ADHD, zaburzenia zachowania i zachowania antyspołeczne U zwierząt wczesna ekspozycja w wieku rozwojowym ma związek z występowaniem chorób neurodegeneracyjnych w późniejszym okresie życia, być może na drodze mechanizmów epigenetycznych. Badania z użyciem metod obrazowania układu nerwowego jak wolumetryczny tensor dyfuzyjny i czynnościowe MRI dostarczają wglądu w neurologiczne podstawy uszkodzenia poznawczego związanego z większą ekspozycją na ołów. Liczne ostatnie oceny ryzyka (np. EFSA, JECFA) świadczą, że badania naukowe jeszcze nie zdołały zidentyfikować takiego progowego poziomu ołowiu w krwi, poniżej którego można by uważać, że jest on bezpieczny dla zdrowia.

Many times in the history of lead toxicology the view has prevailed that „the problem” has been solved, and that exposure to lead is no longer a major public health concern. Each time, additional research hasde monstrated the prematurity of this judgment. In the last decade, an extraordinary number of new studies have illustrated that „the problem” remains, and that it has dimensions never before considered. Children’s intelligence has traditionally been considered to be the most sensitive endpoint and used as the basis for risk assessment and standard setting. For IQ, the dose-effect relationship appears to be supra-linear, with greater deficits per μg/L increment below than above 100 μg/L. Recent studies have found that greater lead exposure in early childhood is also associated with a wide variety of other outcomes, with some associations evident at biomarker levels comparable to those at which IQ deficits are observed. Among these endpoints are poorer academic achievement, ADHD, conduct disorder, and antisocial behavior. In animals, early life lead exposure has been implicated in neurodegenerative disorders later in life, perhaps via epigenetic mechanisms. Studies employing neuroimaging modalities such as volumetric, diffusion tensor, and functional MRI are providing insights into the neural bases of the cognitive impairments associated with greater lead exposure. Several recent risk assessments (e.g., EFSA, JECFA) have concluded that research has yet to identify a threshold level below which lead can be considered „safe”.
 
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