TOXICITY OF DIOXINS
TOXICITY OF DIOXINS
Ten years after the incident, a large scale study by P. Bertazzi e.a. revealed some few more cases of some seldom occuring cancers (that was reported in the media) and some less cases of other, more common occuring 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. | ||
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 (tenthousends 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.
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:
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 haemolytic activity, white blood cells, lymphocytes, and haemoglobin. These differences were subclinical, faded and disappeared with time.
Part of the exposed people were controlled in 1992-1996. Results show that:
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 behaviour, which can be largely influenced by stress in war times or by health scares like in Seveso...
Other subtile effects are found in the amount of the thyroxine 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.
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 industrialised) 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 resistence of breastfeeded 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 milkfat.
| 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 |
The little short- and longterm 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.
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 toxify 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 uncurable cancers and the search for possible remediants...
You are at level two of the Chlorophiles pages.
Created: March 9, 1996.
Last update: February 16, 1999.
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