But as journalist David Kirby notes in Evidence of
Harm — a compelling study on the politics of mercury in vaccines —
many experts who had exonerated thimerosal had received research grants
and even donations from vaccine manufacturers.
While many us experts gave a clean chit to
thimerosal, cases of autism increased in the country. In the early
1980s, only one among 10,000 children in the us
was autistic. By the late 1990s, one in 500 children had the
disease; currently there is one autistic child per 166 newborns in the
us. Experts who incriminate thimerosal for
this rise point out that mercury in vaccines more than doubled between
1988 and 1992. They also cite the contrasting example of Denmark, where
autism afflicts one in 13,000 children — the country banned thimerosal
in vaccines in 1992.
In another study, David Geier and Mark Geier of MedCon, Inc — a
us- based private research laboratory —
evaluated neurodevelopment disorders reported to the country’s Vaccine
Adverse Event Reporting System. They categorised the data into groups of
those who had been administered dpt vaccines
with thimerosal and those who received thimerosal-free vaccines between
1997 and 2001. The former demonstrated a significantly higher incidence
of autism, speech disorder, mental retardation, personality disorders
and thinking abnormalities. The evidence against mercury has not always
been epidemiological. For example, a study by Mary Hornig of the Mailman
School of Public Health, Columbia University, published in Molecular
Psychiatry in June 2004, just months after the
iom report, showed that thimerosal caused autism-like damage in
genetically-susceptible mice. Another study by Boyd Haley of the
University of Kentucky, usa, showed that
mercury reduced an essential protein in nerve cells, tubulin. The
protein is important for the growth of neurons and its depletion has
been linked to the Alzheimer’s disease.
Thimerosal has also been implicated in other nerve disorders. For
instance in 2003, David Baskin of the department of neurosurgery at
Baylor College of Medicine demonstrated that this preservative can cause
membrane and dna damage, and kill nerve
cells, even when administered in small amounts.
The debate has some positive fallout in the us. W
ith legislation to remove mercury from vaccines, the levels of the heavy
metal in vaccines administered to infants in their first six-months has
currently come down to 3 µg from 187.5 µg in the 1980s. Experts are
waiting to see if this intervention reduces the incidence of autism.
The debate can, however, compound the vaccine-related predicaments of
developing countries like India, especially with the increasing
awareness on the link between mercury and autism. A senior-Delhi-based
paediatrician sums this apprehension quite aptly: “The fear of mercury
in vaccines might deter people from innoculating their children”.
But what about alternatives to thimerosal? We do have alternative
preservatives like 2-phenoxyethanol. Drug manufacturers around the world
are also considering the use of other preservatives like benzalkonium
chloride and benzethonium chloride. But says Varaprasad Reddy,
ceo of Shantha Biotechnics, a Hyderabad-based
pharmaceutical company, “We have manufactured vaccines withot
thimerosal. It’s not difficult to produce them. But the
who does not permit us to supply such
vaccines to the unicef ” .
Besides, the use of these alternatives would require a complete change
in the licensing regime. For, Indian Pharmacoepia — a document
that contains guidelines on drug constituents — makes it mandatory for
vaccines to have mercury.
That’s not all. Extensive safety data would be needed for licensing. In
fact, in the us, 2-phenoxyethanol is used in
dpt vaccines manufactured by Aventis Pasteur.
But a study dating back to 2000 indicates that this preservative also
has neurotoxic properties. Occupational exposure to this chemical for
more than a year can lead to cognitive impairments.
There are some other alternatives as well For example, the
U niject device developed by the
international ngo path, obviates the need for
preservative-dependant multi-dose vials. But many experts are not too
sure if the device could be a viable alternative. The device is costlier
than even conventional single-dose vaccines, says Reddy. The latter
costs about Rs 25 per vial, while the new device costs as much as Rs 34.
Apathy and concern
There is another problem far graver than costs of alternative
preservatives. Many experts do not see the need to shift over to
mercury-free vaccines. One of them Suresh Jadhav, executive director,
Serum Institute of India Ltd, Pune, asserts, “There is no proof of the
harm done by vaccines, only perceptions. Using mercury-free, single-dose
vaccines is also not feasible as multi-dose vaccines are far cheaper,”
Indian Pharmacoepia is quite categorical that even single-dose
vaccines contain thimerosal. Reddy agrees that this anomaly should be
corrected, but is not sure that this would make much difference
considering the expenses involved in manufacturing single-dose vaccines.
There are other problems. It’s not incumbent on vaccine manufacturers to
put down information about the presence of thimerosal in the literature
that accompanies the vaccine vials. So, some of the vaccines produced in
the country such as those produced by, gsk
Bharat Biotech do not mention the presence of preservative. This lack
makes it difficult for parents to take the kind of action taken by their
counterparts in the us.
The Union minister of health and family welfare is not totally
impervious to such problems. The national technical advisory group on
immunisation, a body of this ministry, is supposed to convene a meeting
soon to assess the safety data related to vaccines. If needed, the group
will put an alternative vaccination strategy in place. But this meeting
is long overdue. “There should be policy changes. But these should be
implemented quickly without creating a scare,” suggests a senior
paediatrician. Other experts assert that the government should quickly
develop a low cost, effective preservative that is safer than
Exposure to mercury in any case is quite high
in India. An autistic person needs treatment for life and the cost is
very high. It’s time corrective measures are taken.