Science & Technology

“Dancing Cat Fever” – New Culprit Identified for Minamata Mercury Poisoning Tragedy

The Fifties and 60s Minamata tragedy was tied to mercury compounds dumped from a close-by chemical plant, however the exact type of mercury concerned has remained unclear. A brand new research, carried out partly at SLAC, has recognized a beforehand unknown offender. Credit score: Greg Stewart/SLAC Nationwide Accelerator Laboratory

The Fifties and ‘60s poisoning occasion was lengthy attributed to methylmercury, however research at SLAC counsel a distinct compound was accountable. The findings may reshape toxicologists’ understanding of illness associated to mercury poisoning.

The story of one in all historical past’s worst mercury poisoning occasions has a brand new twist. Drawing on subtle X-ray spectroscopy methods, researchers on the Division of Power’s SLAC Nationwide Accelerator Laboratory and the College of Saskatchewan have traced the origins of the Minamata tragedy, which unfolded in Fifties and ‘60s Japan, to a little-studied mercury compound dumped into Minamata Bay. Their research was revealed not too long ago within the American Chemical Society’s Environmental Science & Expertise.

Minamata illness, which is the topic of a movie that premiered February 21, 2020, on the Berlin Worldwide Movie Competition, emerged when “dancing cats” developed neurological signs, together with convulsions. When youngsters and adults within the space additionally started to get sick and die, medical doctors took discover. The illness, which on the time sickened greater than 2,000 individuals – most of whom died – was quickly attributed to industrial waste from a close-by chemical plant, however the actual nature of the mercury compound concerned remained unclear.

Minamata illness is a neurological illness attributable to extreme mercury poisoning. Minamata illness was first found in Minamata metropolis in Kumamoto prefecture, Japan, in 1956. The animal results had been extreme sufficient in cats that they got here to be named as having “dancing cat fever.”

At first, it was thought the plant was dumping an inorganic type of mercury, which microorganisms within the bay reworked right into a extra poisonous natural type known as methylmercury. Extra not too long ago, research of samples from the brains of cats that had been fed plant waste within the late Fifties steered the plant had dumped that natural type straight, however even then questions remained. For one factor, the degrees of methylmercury within the cat samples had been comparatively low, and nobody was fairly positive why. 

In an effort to resolve lingering questions concerning the origins of Minamata illness, a workforce of College of Saskatchewan researchers revisited one of many cat samples in collaboration with Dimosthenis Sokaras and Thomas Kroll, employees scientists at SLAC’s Stanford Synchrotron Radiation Lightsource. At SSRL, the workforce used subtle X-ray spectroscopy strategies together with laptop modeling to make advantageous distinctions between totally different mercury compounds and in the end determine which one resided inside the cat tissues.

“These sorts of samples have very low concentrations of mercury, so getting sufficient of a sign out of them to tell apart the totally different chemical species is fairly demanding,” Sokaras stated. However the workforce was in a position to decide that the mercury compound was neither inorganic nor methylmercury. As an alternative, it was almost definitely α-mercuri-acetaldehyde, the poisonous results of which haven’t been studied in nice element. 

“It was this species that very possible contaminated Minamata Bay and subsequently gave rise to the tragedy of Minamata illness,” stated Graham George, a professor of geological sciences on the College of Saskatchewan and an knowledgeable within the spectroscopy of poisonous molecules, though the researchers usually are not but positive of the implications for public well being and the understanding of mercury poisoning. “Extra work is required to discover the molecular toxicology of those compounds to grasp the methods they could possibly be poisonous to people, animals and the setting,” he stated.

Reference: “Rethinbiochking the Minamata Tragedy: What Mercury Species Was Actually Accountable?” by Ashley Ok. James, Susan Nehzati, Natalia V. Dolgova, Dimosthenis Sokaras, Thomas Kroll, Komyo Eto, John L. O’Donoghue, Gene E. Watson, Gary J. Myers, Patrick H. Krone, Ingrid J. Pickering and Graham N. George, 17 January 2020, Environmental Science & Expertise.
DOI: 10.1021/acs.est.9b06253

Researchers from the Japanese Ministry of the Setting, Nationwide Institute for Minamata Illness additionally contributed to the research. The analysis was funded by grants from the Pure Sciences and Engineering Analysis Council of Canada, the Canada Basis for Innovation, and Canada Analysis Chairs. SSRL is a Division of Power Workplace of Science consumer facility. The researchers used SSRL’s Structural Molecular Biology Program amenities, that are supported by the DOE Workplace of Science and the Nationwide Institutes of Well being, Nationwide Institute of Common Medical Sciences.

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