the toxic truth - Greenpeace

the toxic truth
» ambient temperature: the higher the
temperature, the greater the rate of
evaporation of possible solvents from the
mixture.
» Rainfall: a significant amount of rainfall
would be required to bring down the pH
of the waste. But if there were sufficient
slightly acidic rainwater, the pH of the
mixture would be driven down to the point
where first mercaptans would be released
(between pH11 -10 ) and then, if it fell
even lower (to around pH7-8), hydrogen
sulphide. Rainfall would also result in
further dispersion of the waste. Given
how strongly alkaline it was, there would
be a considerable risk to both people and
the environment in the immediate vicinity
if either had any direct contact with the
waste.
» Quantity of waste dumped and its
composition: the more waste dumped,
the greater the likelihood of significant
exposure to chemicals.
» Method of dumping: if dumping was
into water there would be significant
dilution and mixing of waste. The basicity
of the waste would fall, and individual
substances might become more volatile
as a result.
» Mixing of waste with other materials
such as water/soil/solvents/
absorbents: other chemicals present in
liquid into which the waste was dumped
might also have an effect on what
evaporated. Similarly, if there was any
absorbent material, it might lock the
waste in, slowing subsequent release of
chemicals. The pH of the soil surrounding
the waste would also have an impact on
the basicity of the waste if there was any
significant mixing, potentially reducing pH
and enabling earlier release of chemicals
such as mercaptans.
» Dilution of waste after dumping
Wind speed and direction: any wind
would cause chemicals in the air to
disperse more quickly. People downwind
of the release point would be affected by
chemicals in the air.
» Proximity of the local population: clearly
the closer individuals are to dumped
waste, the more at risk they would be
because their inhalation exposure to
volatilized chemicals would be greater.
The further away people are, the less their
exposure because the concentration of
volatilized chemicals would be diluted
by uncontaminated air. As individuals
can only take in so much air over a given
interval, the lower the air concentration of
a chemical, the less will be inhaled.
» susceptibility of individuals to chemicals
in question: some individuals would be
more susceptible to organic chemicals
than others. Many organic chemicals act
as irritants for people with asthma and
may trigger an asthma attack.
» Volatility of the substances: based on the
volatility of the chemicals in question, it
is likely that most of the chemicals in the
hydrocarbon phase would have evaporated
in a matter of days. Substances in the
aqueous phase would evaporate as the pH
fell, with mercaptans becoming airborne
when the pH was between 10 and 11.
Hydrogen sulphide would be released if
and when pH fell to between 7 and 8, even
if only for a small portion of the waste.
These variables drastically affect estimations
of the likely impacts of the dumping on people
living in the city. This is important because
it concerns the underlying accuracy of any
modelling exercise, including Trafigura’s.
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ANNEX I