Abstract

Immunizations for infants and children are facing a controversy. Pediatricians are strongly concerned about preventing epidemics and immunize babies with up to 27 immunizations against 15 diseases before age two, while parents see the long-term adverse events as a threat to their children. There are three components of vaccines thimerosal, formaldehyde, and aluminum salts that have been of special interest to the public because of the increasing awareness of their toxicity to humans. The objective of this study was to summarize existing data on the effects of adjuvants and preservatives found in vaccines on humans.

Accumulation of mercury, which is the main ingredient of thimerosal, occurred mainly in the brain but not in the blood. Mercury crosses the blood-brain barrier and binds to lipoproteins in the brain. Inorganic mercury increased the number of microglia in the brain, while decreased the number of astrocytes. Thimerosal retarded growth and caused hypoactivity in autoimmune disease sensitive mice. The exposure to ethylmercury caused genetic and neurological alterations. Formaldehyde has been shown to cause cytotoxicity and genotoxicity. It also induced DNA-protein crosslinks in proliferating and non-proliferating cells. Blood cells exposed to formaldehyde with raised levels of DNA-protein crosslinks resulted in an increase in sister chromatid exchange rather than micronuclei. An allergic skin reaction was observed after the injection of adjuvants. The administration of aluminum hydroxide resulted in lack of behavioral and motor reactions and a high number of apoptotic neurons. Additionally, high numbers of reactive astrocytes implicated an inflammatory response. Aluminum was shown to induce toxicity in neurons.

Index Entries: vaccine, adjuvant, thimerosal, formaldehyde, adverse event