Chemical cocktail affects humans and the environment

[OKIsItJustMe]

http://www.eurekalert.org/pub_releases/2010-03/uog-cca032810.php

Public release date: 28-Mar-2010

Contact: Thomas Backhaus
[e-mail]
46-317-862-734
http://www.gu.se/english">University of Gothenburg

Chemical cocktail affects humans and the environment

Throughout our lives we are exposed to an enormous range of man-made chemicals, from food, water, medicines, cosmetics, clothes, shoes and the air we breathe. At the request of the EU, researchers at the University of Gothenburg, Sweden, have looked at the risk of "chemical cocktails" and have proposed a number of measures that need to be implemented in the current practice of chemical risk assessment.

In 2005 an American study showed that newborn babies have an average of 200 non-natural chemicals in their blood - including pesticides, dioxins, industrial chemicals and flame retardants. In a Swedish study, the Swedish University of Agricultural Sciences found 57 different pesticides in Swedish rivers and streams, many of them occurring simultaneously. However, the effects of chemicals on humans and the environment are traditionally evaluated on the basis of single substances, chemical by chemical.

Complex cocktail

Research has shown that this type of approach is inadequate as the chemicals that we use form a complex cocktail. The EU's environment ministers have therefore urged the European Commission to step up its risk assessments and amend the legislation on the combination effects of chemicals. In concrete terms, the Commission has been tasked with producing recommendations in 2010 on how combinations of hormone-disrupting substances should be dealt with on the basis of existing legislation, and with assessing suitable legislative changes in 2011.

Unambiguous research results

In order to map out the current situation, researchers from the University of Gothenburg and the University of London carried out a review of the state of the art of mixture toxicology and ecotoxicology. The study showed that all the relevant research is unambiguous: the combined "cocktail effect" of environmental chemicals is greater and more toxic than the effect of the chemicals individually.

Guidelines needed

"The number of chemical combinations that the Earth's living organisms are exposed to is enormous," says Thomas Backhaus, researcher at the Department of Plant and Environmental Sciences and co-author of the report. "Assessing every conceivable combination is not therefore realistic, and predictive approaches must be implemented in risk assessment. We need guidelines on how to manage the chemical cocktail effect so that we can assess the risks to both humans and the environment."

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The study, State of the Art Report on Mixture Toxicity, is published by the EU's Directorate-General for the Environment. Download the report at: http://ec.europa.eu/environment/chemicals/effects.htm

Contact

Thomas Backhaus, Department of Plant and Environmental Sciences, University of Gothenburg, tel: [phone] [e-mail]

[ensho]

1. and this cocktail also affects brains

and very much baby/children's brains. which means teaching/schools are having to deal with it. and the amount of changed brains will keep on growing in numbers and will mean different kinds of teaching and different kinds of school rooms.

and doctors/scientist should be ramping up their work to understand the cocktail changes so that the children can get the best help possible in schools.

[enki23]

2. that sounds good. however...

when you start looking at the effects of mixtures, even just *binary* mixtures, except in a few very specific sorts of instances, you run into a problem that is combinatorial in its complexity. we don't even have anything approaching the necessary resources to test all the *single* compounds adequately.

i do appreciate the attempt to give me long term job security. i also appreciate the concern about possible synergistic effects of mixtures. unfortunately, i also appreciate (in a different sense of the word, perhaps) the staggeringly impossible task of actually accomplishing something like this, even if we were to limit it to a much reduced list like the high production volume chemicals. and if we were to try to look at the entire chemical universe we live in? every toxicologist in the world would have lifetime employment just trying to untangle a minute fraction of the potential interactions of all the compounds that are found in, say, a carrot. and yes, that includes even the most organic of possible organic carrots. the platonic ideal of organic carrots.

so... whee. people will occasionally make noises about this, and the fads will come and go, but we will never be able to comprehensively test such a thing. at least, not until the day when we have sufficient knowledge of biology, chemistry, and physics (and sufficient processing power!) to simply model the whole damned thing. maybe we could do some small fraction with cell-based assays in the meantime, but the results will be extremely, extremely limited. to put it mildly. humankind will almost certainly have long since vanished from the universe before such a thing was even remotely feasible.

[OKIsItJustMe]

3. "Assessing every conceivable combination is not therefore realistic..."

(I think you're in agreement with the authors.)

[enki23]

4. one significant difference. i have very little faith in the predictive end of it.

the idea that we are in any position to go about developing predictive toxicology for mixtures, other than *maybe* for a few very limited and specific circumstances, is (if anything) even *more* absurd. you can't predict these sort of complex interactions with much accuracy. real biology is far too complex. the model parameters multiply beyond control even for models of tiny subsets of our biology. you should see what goes into trying to model "just" the thyroid axis.

i actually do agree with these people even more than this, in all probability. the authors were asked to come up with a report, and so they did the best they could. like i said, people will make noises about this on occasion. but i would wager every cent i will ever earn that no large-scale, significant progress will ever be made on this front.

it's not that we will never know anything about synergistic effects. sometimes we have reason suspect specific effects, and can test them individually when practical. but predictive models require sufficient good information to build them. and in this case, what would constitute "sufficient good information" is immense. really, really immense. sadly, i can't help but reach the conclusion that we will never have anything even approximating a successful effort to accomplish this. the intersection of toxicology, economics, politics, and (unfortunately) reality just isn't pretty.

[OKIsItJustMe]

5. Understood

It's a daunting task to say the least.

However, given the advances in "Computational Chemistry" & "Computational Biology" it may be possible to make some progress...