PFHXS has been detected in ringed seal in the Arctic. Foto: NOAA Seal Survey/Wikipedia.

New candidates for the list of worst environmental toxins

The Norwegian Environment Agency is of the opinion that more substances and groups of substances should be added to the national list of Priority Substances.


It is a national goal that emissions and use of substances that may represent a serious threat to health and the environment must be continually reduced with a final goal of zero emissions by 2020.

The list of priorities stipulates more than 30 substances and substance groups covered by this target. The criteria a substance must meet to be placed on the list are stated in the Stortingsmelding (white paper) Together for a toxin free environment (in Norwegian):
1. Substances that are persistent, bio-accumulative and have serious long-term effects on health or are highly toxic to the environment.
2. Very persistent, and very bio-accumulative substances (documentation of toxicity is not required).
3. Substances that are detected in the food chain at levels which give rise to an equivalent reason for concern.
4. Other substances, such as substances that have endocrine disrupting effects and heavy metals, that give rise to an equivalent level of concern.

The priority list provides the Authorities with several instruments to limit the use of the substances and minimise emissions by measures such as a total ban, limitations and strict requirements for what is allowed in terms of emissions and for waste management.

A substance that fulfils the criteria for being included on the priority list, is hazardous to such a level that the so-called duty to substitute occurs. This means that companies using the substance are legally required to find alternatives if this can be done without unreasonable expense or disadvantage.

Find out more at Miljøstatus

UV substances belonging to the substance group benzotriazoles are used to protect materials against radiation from the sun.

Worst offenders

These substances degrade slowly and are difficult to remove once they have been introduced to the environment.

“These can be toxic and they accumulate in animals. They are found in breast milk and we are finding more and more in the environment. The Norwegian Environment Agency’s monitoring has revealed benzotriazoles in cod liver and prawns from the Oslo Fjord and in sediment samples from Mjøsa. This is no place for them. This is why we want these substances added to the priority list,” says Ellen Hambro, Director General of the Norwegian Environment Agency.

When a substance is added to the national list of priority substances, popularly called the worst offenders list, it is considered to be a serious threat to health and the environment (see fact box).

There are more than 30 substances and groups of substances currently on this list. The aim is to continually reduce emissions, with a target of completely stopping them by 2020.

The Norwegian Environment Agency also suggests adding several organic tin compounds to the list: Dibutyltin compounds (DBT) and dioctyltin compounds (DOT). A number of highly toxic pollutants are hidden behind these difficult names.


DBT and DOT are collective terms for a type of compound used in glue, paint and plastic products, among other things.

These substances have similar health and environmental effects to the more well-known and related substance group TBT, which is already entered on the list. TBT was previously used in anti-fouling paint and in substances used for impregnating wood, but is now banned.

“DBT and DOT can harm the immune defences of humans and animals, the substances can disturb the hormonal balance and harm reproduction and they are not easily degradable. They can be poisonous to water-borne organisms and we have found them in mussels, dog whelks and periwinkles, among other things. There is absolutely no doubt that we wish to get rid of these, “ says Hambro.

The newest worst offender is another tongue twister. Perfluorohexanesulphonic acid (PFHxS) is used in firefighting foam, paint, carpets, textiles, impregnating agents, electronics and non-stick coatings for cookware.

PFHxS is found in the environment in many species such as Arctic cod, Arctic gulls, ringed seals and polar bears. This substance is suspected of disturbing hormonal balance and animal studies have shown that the substance may lead to behavioural changes.


PFHxS, like PFOS (another perfluorinated compound on the list of Priority Substances), is very difficult to eradicate from the environment.

“In addition studies on humans show that PFHxS is very difficult to get rid of when it has entered the body. The half-life is as long as eight years. It has also been found in breast milk and can also be transferred to the foetus. All this points to qualifying for a clear place on the list of Priority Substances,” says Hambro.

“We are of the opinion that these three groups of substances are so harmful that we are asking the Ministry of Climate and the Environment (KLD) to include them in the priority list,” concludes the Director General of the Norwegian Environment Agency.


head of section Heidi Morka
Chemicals and Waste Department
phone: +47 959 61 349