Environmental Engineering Reference
In-Depth Information
very low temperatures, which are pumped into a combustion chamber for ignition.
Sometimes an inert gas is used instead and this is forced under pressure into the
chamber; these are often used in satellites to enable small changes of orbit.
Solid-fuelled rockets generally have a lower performance than liquid-fuelled
ones and so are not often used to launch medium-to-large payloads such as com-
mercial satellites or major space probes. However, they are frequently used as strap-
on boosters to increase payload capacity or as spin-stabilised add-on upper stages
when higher-than-normal velocities are required. Solid rockets are used as light
launch vehicles for low Earth orbit (LEO) payloads under 2 t or escape payloads up
to 1,100 pounds.
Perchlorate is a major oxidiser in solid rocket fuel and can interfere with iodide
uptake into the thyroid gland (which helps to regulate the body's metabolism). It is
also highly soluble and has been found to be a pollutant in drinking water and food
sources in more than 20 states in the United States. In 1992 the US Environmental
Protection Agency (EPA) proposed a safe reference dose (SRD) level of four parts
per billion (ppb) for perchlorates in drinking water. A group of manufacturers and
users of rocket fuel (including Aerojet, American Pacifi c Corporation, Kerr-McGee
Chemical and Lockheed Martin) joined together to form the
Perchlorate Study
Group
(PSG) and provided the EPA with evidence they had gathered on the health
effects of perchlorate. Subsequently, in 2005 the EPA raised the SRD to 24.5 ppb.
However, Madsen and Jahagirdar (
2006
) claim that rather than supplying the EPA
with good scientifi c evidence, the PSG 'paid millions of dollars to fund misleading
research and millions more to infl uence the scientifi c and public debate'. In addi-
tion, a 2005 report released by the US
National Academy of Sciences
that was sup-
posed to evaluate the potential health threats posed by perchlorate was strongly
criticised by the US
National Resources Defense Council
who state in a press
release that:
Documents obtained from a series of Freedom of Information Act requests and lawsuits
against the White House, Department of Defense and the Environmental Protection Agency
indicate that the panel was subjected to massive pressure to downplay the hazards of the
chemical. (NRDC
2005
)
The issue remains controversial and the risks to health and the extent of pollution
from rocket fuel remain unclear. A proper independent study is still required to test
these areas of concern, and several US states have initiated regulatory reviews to
prepare a drinking water standard for perchlorate. In the mean time, California and
Massachusetts have set 'public health goals' for contaminant levels of 6 ppb and
1 ppb, respectively.
12
This situation is probably familiar to many campaign groups who fi nd that so-
called scientifi c evidence is far from scientifi c but has in fact been commissioned
and monitored by corporations with a vested interest in the results. The problem is
12
See more at
http://www.drinktap.org/home/water-information/water-quality/perchlorate.
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