The manufacturers do not mention the presence of mercury (thimerosal) or other dangerous preservatives such as aluminium in the COVID-19 Vaccines. Hopefully, this is true. However, I am not aware of any independent laboratry cross checking the vaccines ingredients to verify this, so we can only take their word for it.
What we know is that the AstraZeneca vaccine contains an emulsifier called Polysorbate 80. Evidence suggests that this ingredient is potentially toxic. Some studies have found a link between Polysorbate 80 and infertility in mice. Others have found a real connection between ingesting Polysorbate 80 and the development of bowel problems, including exacerbation of Crohn’s Disease. It seems that the risk is small, but not inexistant.
The AstraZeneca vaccine also contains the compound disodium edetate dihydrate. This chemical is considered a health hazard. According to PubChem, it is harmful if swallowed, harmful in contact with skin, harmful if inhaled, causes damage to organs through prolonged or repeated exposure and harmful to aquatic life with long lasting effects45. I could not find any specific data on harm when injected, but of course no one would inject something that has been proven harmful when swallowed, inhaled and in contact with skin…
Additionally, the potential synergistic toxicity of excipients is unknown.