Polio vaccines containing simian virus 40 may cause human cancer.

2004 NOV 3 - (NewsRx.com & NewsRx.net) -- Scientists have found mixed evidence for a causal association between polio vaccines contaminated with simian virus 40 and cancer.

According to published research from Canada, "In 1960, it was discovered that simian virus 40 (SV40) contaminated up to 30% of the poliovirus vaccines in the U.S. This contamination arose because the vaccines were produced in monkey kidney cell cultures harboring SV40 between 1955 and 1963. During this period, approximately 90% of children and 60% of adults in the USA were inoculated for polio and possibly exposed to SV40. Many epidemiologic and molecular pathogenesis studies have been conducted in order to identify potential cancer risks since this 'natural' experiment began."

"Productive SV40 infection has the potential to initiate malignancy in a variety of target tissues," said Tam Dang-Tan and colleagues at McGill University. "Epidemiological studies that investigated the relationship between SV40 infection and cancer risks have yielded mixed results. Studies can be grouped into three categories based on their exposure definition of SV40 infection: use of vaccination or birth cohorts as proxy variables for infection, follow-up of children of pregnant women who received polio vaccines, and direct molecular detection of the virus or serologic detection of anti-SV40 antibody responses."

"A meta-analysis ...