Because the shark was initially preserved poorly, it began to deteriorate and the surrounding liquid grew murky. Hirst attributes some of the decay to the fact that the Saatchi Gallery had added bleach to it.  In 1993 the gallery gutted the shark and stretched its skin over a fiberglass mold, and Hirst commented, "It didn't look as frightening ... You could tell it wasn't real. It had no weight."  When Hirst learned of Saatchi's impending sale of the work to Cohen, he offered to replace the shark, an operation which Cohen then funded, calling the expense "inconsequential" (the formaldehyde process alone cost around $100,000).  Another shark was caught off Queensland (a female aged about 25–30 years, equivalent to middle age) and shipped to Hirst in a 2-month journey.  Oliver Crimmen, a scientist and fish curator at London's Natural History Museum , assisted with the preservation of the new specimen in 2006.  This involved injecting formaldehyde into the body, as well as soaking it for two weeks in a bath of 7% formalin solution.  The original 1991 vitrine was then used to house it. 
In sum, federal attempts to reduce the palatability of industrial alcohol came well before Prohibition, and efforts to intensify the risks of consuming it were both well- known and controversial at the time. Such evidence as we’ve seen does not support the the implication that the government set out to purposely kill drinkers of alcohol, although Prohibition-era lawmakers and public health experts decried what they described as a callous disregard for those who died as result of drinking denatured alcohol.
CIR Safety Review: DMDM Hydantoin is poorly absorbed from the skin. In a laboratory study, oral exposure to DMDM Hydantoin did not result in any adverse effects. The CIR Expert Panel noted that DMDM Hydantoin is a formaldehyde donor in aqueous media. They attributed positive results in some in vitro mutagenicity studies to formaldehyde release. In these studies, the concentrations of DMDM Hydantoin tested were higher than those used in cosmetic and personal care products, likely resulting in much higher concentrations of formaldehyde than found in products. Clinical studies revealed some observations of skin irritation which could also be related to the release of formaldehyde from DMDM Hydantoin.