Despite substantially reduced emissions of most well known persistent organic pollutants, e.g. PCBs and dioxins, the danger is far from over. The toxic substances are still present in the environment and in our bodies. Moreover, a number of similar pollutants have recently been discovered in the environment, according to the Swedish Environmental Protection Agency.
The Agency is publishing the results of the latest Swedish research on toxic pollutants in a new report, Monitor 16. The findings include animal experiments which show that the brain in young specimens can be damaged by even extremely small doses of environmental pollutants.
"There is every reason to continue keeping a vigilant eye on what these chemicals are doing to the environment and to ourselves. We know, for example, that they can disrupt hormonal systems and we suspect that they can contribute to birth defects and health damage in infancy. Furthermore, many factors are still unknown regarding the effects of organic pollutants. The picture is much more complex than hitherto believed, and new substances are being discovered all the time", says project leader Niklas Johansson at the Swedish Environmental Protection Agency.
Brominated flame retardants are one of the more controversial groups of substances. The total use of these chemicals is still increasing. They are used, for example, in electronic equipment.
"It is important that the problems of toxic organic pollutants are prevented at source, i.e. making sure that substances with properties which entail a risk are not produced in the first place. But we still need to understand better how such substances affect the central nervous system, hormonal systems, the immune system and tumour formation", recommends the project group heading the research programme on persistent organic pollutants and which has advised the production of the Monitor 16 report.
Briefs from Monitor 16:
Reduced levels of toxic pollutants
For several years, levels of DDT, PCBs, dioxins and hexachlorobenzene have fallen considerably in the Swedish natural environment. Levels of brominated flame retardants were still increasing in the 1980s, but are now falling. However, practically nothing is known about how the abundance of most other persistent organic pollutants is changing in the environment and in ourselves.
Not more toxic pollutants in the north
The general belief that toxic pollutants accumulate in northern regions can be questioned. The theory is not supported by Swedish environmental data. On the contrary, levels are considerably lower in the north of Sweden than in southern regions. Furthermore, concentrations of for example PCBs, DDT and dioxins appear to decrease at least as rapidly in northern parts of the country as in the south.
Alarming brain damage in mice
Even very small doses of toxic pollutants can cause lifelong neurological disturbances in laboratory animals. Ten day-old mice exposed to a few micrograms of DDT will suffer permanent damage to the central nervous system. There are no external changes, but for the rest of their life they will endure reduced learning capacity and hyperactive behaviour, showing irreparable brain damage. Other toxic pollutants, such as PCBs and brominated flame retardants, can also cause similar effects even in small doses.
"Are human babies as sensitive as young mice? We do not know, but we cannot ignore the risk", according to Per Eriksson, scientist at the University of Uppsala. (His findings are also presented in the new report Prenatal Developmental Neurotoxicity of PCBs, Swedish Environmental Protection Agency report 4897).
Monitor 16, a broad-based popular account of ten years of Swedish research in the field of persistent organic pollutants, has also been published in English. It is written by Claes Bernes at the Swedish Environmental Protection Agency. The intention is to publish around ten additional reports in English, which will summarise the experiences from various aspects of this field of research.
Next week, 650 scientists from all around the world will meet in Stockholm to discuss the latest scientific findings concerning persistent organic polllutants, at the Dioxin98 conference. The conference is organised by the Swedish Environmental Protection Agency, the National Chemicals Inspectorate, the Karolinska Institute and Stockholm University. Sweden has long been in the forefront regarding research on toxic pollutants. For example, it was the Swedish scientist Sören Jensen who first identified PCBs as a chemical hazard in all living things. Also, Christoffer Rappe was one of the first to be able to analyse very low levels of dioxins.
"Monitor 16 Persistent Organic Pollutants, A Swedish perspective on an international problem"