Mercury is a deadly toxic element, and its acute toxicity is well known-it causes kidney failure, muscle tremors, memory loss, and even life-threatening. Now the mercury content in the fillings that dentists use to fill teeth often reaches 50%. Therefore, every responsible dentist should remove all mercury-containing fillings from the mouth of a filling patient and replace them with plastic fillings. Which of the following statements best contradicts the above point? ['Mercury is also found in some seafood, alcohol, beverages and pharmaceuticals.', 'Fillers made of plastic are much more expensive than mercury-containing ones and are easily damaged.', 'Mercury is highly toxic, but 50% mercury-containing fillers used by dentists do not substantially harm physical health.', 'Most patients are satisfied with the use of mercury-containing fillings.']