TOXICITY OF DIOXINS
FAIRY-TALE
In 1985, EPA found that dioxin was the most potent carcinogen yet tested.
Greenpeace report 'Achieving Zero Dioxin' - July 1994 [1].
FACTS AND FIGURES
Parts of this page
The exaggeration of Greenpeace
Greenpeace is completely outdated about the carcinogenic effect of dioxins.
At this moment the class of nitro-PAH's
(nitrated polycyclic aromatic hydrocarbons) are found to be the most potent
carcinogens [5].
Some toxic chemicals do have equal effects on different animals at
nearly the same concentration. This is not the case for dioxins. Dioxins
are extremely toxic for Guinea pigs, but a thousand times less toxic for
other animals. Humans seems to be much more resistant to the toxicological
and carcinogenic properties of dioxins.
Since the accident in Seveso, Italy, where a chemical reactor overheated
and a cloud of reaction products, including a few hundred grams of the
most toxic dioxin, was emitted over the neighborhood, this is for Greenpeace
the symbol of what can go wrong in a chemical factory. Of course, this
was a serious incident, and incidents of that kind should be avoided with
all means possible.
A lot of animals, especially grass eaters, died within a few days to
a few weeks, but no human died! The only people killed, were the
director of the factory, murdered by the Red Brigades and under the panic
of that moment, 17 abortions, from which the fetuses were investigated
and from which no aberration, related to the accident, was found. There
was a lot of people affected by a skin disease, called chloracne, which
all was cured in a few months to a few years.
Also the ground of Seveso was affected in more or less serious ways.
For this reason, the surroundings of the incident were categorized in three
classes, the most polluted, the A-class had the highest dioxin content.
Cancer incidence in Seveso
Ten years after the incident, a large scale study by P. Bertazzi e.a. revealed
some few more cases of some seldom occurring cancers (that was reported
in the media) and some less cases of other, more common occurring cancers
(that was not reported in the media!). The total result: in Seveso
there are less cases of cancer, compared with a non-affected reference
area.
Cancer incidence at Seveso, ten years after the accident: Average
dioxin found in ground expressed in microgram I-TEQ per square meter. Average
dioxin found in blood expressed in parts per trillion (ppt).
| Cancer incidence at Seveso, ten years after the accident |
| zone |
inhab. |
dioxin in
soil |
dioxin in
blood |
expected
cases |
real
cases |
|
|
|
|
|
|
| A |
724 |
300 |
10,000 |
19 |
14 |
| B |
4,824 |
50 |
300 |
130 |
112 |
| R |
31,647 |
5 |
10 |
850 |
765 |
| ref. |
181,579 |
< 1 |
n.d. |
|
|
Source: Cancer incidence in a population accidentally exposed to
TCDD [12].
n.d.: not detectable
Recently, the WHO has declared the Seveso type dioxin (2,3,7,8 TCDD)
as a human carcinogen, based on the consequences of severe accidents in
several chemical works, where workers received extreme high levels of this
dioxin type (ten thousands of times higher than background!). The rise
of cancer incidences in a life time was app. 40% for the highest exposed
people. That has to be compared with a 20 times (or 2,000%) rise in cancer
incidence for smokers...
The other 209 types of chlorinated dioxins and furans are not classified
until now, because of lack of reliable data.
Other diseases in Seveso
Some twenty years after the accident, the results of a long-term study
were presented at a symposium [52]:
Data presented from health monitoring of the Seveso residents of 1976
to 1996:
-
Chloracne was the only clinical alteration positively correlated to TCDD
contamination levels, even if not completely and with different individual
susceptibility.
-
Miscarriages, perinatal mortality, low birth weight, or congenital malformations
did not significantly increase.
-
Clinical monitoring of children and adults did not demonstrate any clear
association between morbidity (except chloracne) and TCDD exposure.
Laboratory results showed minimal differences between exposed (even if
very highly exposed) and controls in the period of acute exposure (1976-1977)
for some liver function tests, complement hemolytic activity, white blood
cells, lymphocytes, and hemoglobin. These differences were sub clinical,
faded and disappeared with time.
Part of the exposed people were controlled in 1992-1996. Results show
that:
-
No laboratory pathology was related to TCDD levels both in acute and chronic
phase.
-
Cytochrome P450 IA2 does not seem to be induced after about 17 years in
exposed people compared to control as measured by Caffein Breath Test.
-
Half life of TCDD is longer in women (about 9 years) than in men (about
7.5 years) while in children much shorter.
A control of people born after 1976 from exposed parents was recently started.
In A zone from 9 months after the accident to December 1984, corresponding
to about one TCDD half-life in adults, there was a significant modification
of the sex ratio with an excess of females (26M vs 48F) associated to high
TCDD exposure of both parents. This fact declined (60M vs 64F) there after
and is no longer significant.
Comment:
The latter is quite remarkable, because even after 8 years, half of
the dioxins of the accident are still in human's fat. So if the amount
is still 5,000 times higher (average for the highest exposed population
in zone A) than for not-affected people, why is the ratio then back to
normal if dioxins were the origin? Further that is contradicted by the
fact that, with the same chemicals involved, the Vietnam war veterans show
a higher than normal male to female birth ratio!
As we have learned from other discussions, the male to female ratio
of births is highly influenced by sexual behavior, which can be largely
influenced by stress in war times or by health scares like in Seveso...
Toxicity of dioxins in small amounts
Even if there is a higher cancer incidence rate found at Seveso or other
dioxin accidents, that wouldn't tell a lot about the possibility of having
cancer at lower amounts. In animal experiments, huge amounts of dioxin
give more mortality, more cases of cancer and a lot of other unpleasant
phenomena. According to Bruce
N. Ames, the world famous toxicologist, dioxins are cancer promoting
at low dose, when fed to animals after other carcinogens like aflatoxins,
but give lower cancer rates when fed before other carcinogens.
See Nature's
Chemicals and Synthetic Chemicals: Comparative Toxicology [13].
In the same article, Bruce N. Ames compares the toxicological effect
of the daily intake of dioxins with that of natural toxics in our food.
If the effect of dioxins is related to the possibility of induction of
the Ah-receptor in our cells, the daily amount
of dioxins can be compared with the amount of natural indole carbinol found
in 100 grams of coleslaw or 20 grams of Brussels sprouts, which has the
same effect on the Ah-receptor. The possible carcinogenic effect of our
daily intake is less than that of alcohol in drinking one beer in 125 years
and the possibility of birth defects is less than drinking one beer in
3000 years.
Other subtle effects are found in the amount of the thyroxin
hormone in newborn children, which is about 15% higher during several weeks,
when the average dioxin content in mother's fat is twice the average. Dioxins
are also suspected of playing a role in vitamin K deficiency in newborn,
and of endometriosis. But the latter is
not confirmed in a large study of Seveso residents, where no significant
relation was found between dioxin contamination and endometriosis [80].
Dioxins and mother's milk
In The Netherlands, together with Belgium the country with the highest
dioxin content in mother's milk, an investigation was done to see if mother's
milk still was good for children [50]. The
amount of dioxin in mother's milk is about ten times higher than in cow
milk, so newborn children can ingest relatively high doses of dioxin (and
PCBs), compared to their body weight. Even
before the child is born, dioxins and PCBs can pass from the mother to
the child. In the investigation, children from mothers of two different
regions (semi-rural and heavily industrialized) were compared, half of
each region were fed with mother's milk, half with formula milk (or Artificial
Baby Milk - ABM - the correct term used by the WHO). There was a wide variety
in PCB/dioxin levels between individuals as well as in quantity as in toxicity
of the different congeners, quantities ranging from 1:7 to 1:50.
The results of the investigation were:
"Prenatal PCB exposure has a small negative effect on the psychomotor
score at 3 months of age. Breast-fed infants scored significantly higher
on the psychomotor scale at 7 months of age [note: the breast-fed infants
with the highest amount of dioxins/PCBs were equal to formula-fed infants].
The mental outcome at 7 months of age is positively influenced by breast-feeding
per se, the perinatal exposure to PCB's and dioxins does not influence
this outcome. Breast-fed infants never scored significantly lower compared
to formula-fed infants. At 18 months of age the development is neither
affected by PCB and dioxin exposure nor by feeding type."
As even in the highest contaminated group of the highest contaminated countries,
the results of breastfeeding are in general better than for formula milk,
then breastfeeding still is the best food for babies... Especially as the
resistance of breastfed children to infections is much higher. The scaremongery
of some groups and newspapers against the use of mother's milk, because
of the high dioxin content is in any case not justified. Only the use of
some extra vitamin K is justified.
Amounts and trends of dioxin found in mother's milk in different
countries
All figures expressed in picogram I-TEQ
per gram of milk fat.
| Trends of dioxin levels in mother's milk |
|
|
|
| COUNTRY |
1987/88 |
1992/93 |
| Thailand |
4.9 |
|
| New Zealand |
5.8 |
|
| India |
6.0 |
|
| Hungary |
10.2 |
8.2 |
| Croatia |
11.9 |
11.0 |
| USA |
16.6 |
|
| Finland |
16.8 |
16.8 |
| Norway |
17.8 |
10.6 |
| Denmark |
17.8 |
15.2 |
| Austria |
17.9 |
10.8 |
| Vietnam |
18.3 |
|
| Canada |
18.5 |
14.5 |
| Poland |
20.8 |
|
| Sweden |
22.0 |
|
| Japan |
23.9 |
|
| Germany |
31.8 |
16.5 |
| United Kingdom |
33.1 |
16.6 |
| Netherlands |
37.1 |
22.4 |
| Belgium |
37.6 |
24.8 |
Source: WHO - 16th symposium on chlorinated
dioxins and related compounds [51]
Some countries only from the first round.
The little short- and long term effects of dioxins, seen until now do
not justify the enormous scare, abused by Greenpeace and other groups to
accuse the chlorine industry of poisoning people and especially their children.
Of course, that does not mean that one should not reduce the emissions
of dioxins as far as reasonable possible. Lucky, the amount of dioxins
in the food chain is lowering now, thanks to the measures taken at incinerators
of all kind and at the metal industry. See also "Chlorine and bio-accumulation"
(not yet ready) and Sources of dioxins.
THE OTHER TOXICANTS
A lot of the above investigations are biased by chlorine-free bio-accumulating
materials like PAH's and nitro-PAH's.
These were not measured in all of the above mentioned research. Because
of several of those materials have dioxin-like effects, this would have
given a clearer sight on the possible effects of dioxins alone.
If you see the enormous amounts of such materials, released from combustion,
this would be worthwhile an investigation. E.g. the combustion of one million
tons of wood per year in The Netherlands gives, besides 24 times more
I-TEQ
dioxins than the whole chlorine industry and high amounts of carbon monoxide,
also 70 tons of PAH's. Besides the proven
potent carcinogenic effect of several of its members, the direct toxicity
is less pronounced. But even if we assume that the average toxicity is
a thousand times less than of dioxins, the toxicity of PAH's
only from burning wood is equivalent to 70 kilograms of I-TEQ
dioxins per year! or 140 times the total emission of dioxins to air per
year in The Netherlands. See also the emissions of PAH's
and dioxins in Flanders.
CONCLUSION
There is no reason to treat the toxicity of dioxins different from chlorine-free
toxic, persistent and bio-accumulating materials like PAH's.
And there is no reason at all to accuse the chlorine industry to intoxicate
mother's milk and poison unborn and newborn babies, like Greenpeace does.
Because of the enormous scare, introduced with the Seveso accident
and the symbol function it has for Greenpeace and other environmental groups,
high amounts of money are spent in research of the possible long-term effects
of dioxin on the body. If you see the meager results of all those investigations,
al that money was better spent in research of real problems, like the search
for the mechanism which causes until now incurable cancers and the search
for a possible remediate...
You are at level two of the Chlorophiles pages.
Created: March 9, 1996.
Last update: May 10, 2002.
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