The autism epidemic in the United States, starting in the 1980s, and the suspected link between autism and mercury in vaccines, led to the removal of most mercury containing vaccines in the West

Leading doctors have urgently called for an end to the use of mercury in vaccines to avoid potential threat to health of children.

"Continuing to use this potentially toxic substance, when there is little justification for it, will erode the trust of the public and endanger many public health initiatives," warn Jacob Puliyel and Ritika Chhawchharia of the Department of Paediatrics at St Stephens Hospital in New Delhi. Their warning is published as a commentary in the Indian Journal of Medical Ethics.

Thimerosal – a mercury-based preservative is used to prevent bacterial contamination of vials which are entered multiple times, i.e. vials containing multiple doses of vaccines. Preservatives are not required for single-dose ampoules.

The autism epidemic in the United States starting in the 1980s and the suspected link between autism and mercury in vaccines led to the removal of most mercury containing vaccines in the West by 1999. But Thimerosal is used in vaccines meant for developing countries, the doctors say.

Based on the argument that single-dose vials of vaccines (though free from mercury) are expensive to make and hence uneconomical for the third world, the vaccine manufacturers sell multi-dose vials (which contain mercury) to developing countries.

Apart from a lower cost-per dose, it is also argued that the multi-dose vials are most suited for countries like India as they require less cold storage space.

Puliyel and Chhawchharia, in their commentary, demolish these presumed advantages by noting that the benefit of smaller storage space is offset by vaccine wastage which is said to be as high as 60% with multi-dose vials. They also point out that the economics is flawed because single dose ampoules made in India have a maximum retail price of less than Rs3 per vial "and as such, use of single dose vials would be cost saving in India."

"Thus under actual usage conditions, it would appear that multi-dose vials do not afford any real economic benefits for developing countries," the doctors say. "In the Indian context where single dose ampoules are inexpensive to manufacture, switching to preservative-free, single-dose vials for vaccines may, in fact, save costs."

Puliyel and Chhawchharia admit that historically, there may have been reasons to use Thimerosal with vaccines, but they do not apply any longer because single-dose, Thimerosal-free vaccines vials are cheaper now. "Long-term harm may be done to all public health initiatives if international organisations do not act decisively to remove the potential threat posed by the use of Thimerosal in vaccines," they caution.

(Jacob Puliyel is the Head of Paediatrics at the St. Stephens Hospital in New Delhi.)