Certain chemicals are suspected of upsetting the hormonal equilibrium of man and beast, and some of these are used as the UV-filter in body creams. Two of these sun-blocking chemical compounds have been discovered in brown trout caught in seven Swiss rivers by Empa researchers working together with the Agroscope FAW in Waedenswil. The concentrations found in the trout were about ten times higher than those found in whitefish and roach caught in Swiss lakes.

Caption: One of the brown trout (Salmo trutta fario) caught by Empa and Eawag researchers in a total of seven Swiss rivers.

One possible explanation for this is that waste water treatment plants, despite modern technology, cannot completely remove all chemicals pollutants from the water, reported the researchers in the current issue of the scientific journal “Environmental Science and Technology“.

Sun cream, skin cream, body lotion, lip balm, hairspray or shampoo – there is hardly a body care product available today which does not contain a UV blocking filter. These substances are intended to protect us from the damaging effects of the sun’s rays and worldwide several hundred tonnes are produced annually. Recently, however, because of their similarities to hormones various substances including some UV filters have come under suspicion of causing health and reproductive problems in both humans and animals. Fish with malformed genitalia and hermaphrodite baby polar bears have been making headlines.

For these reasons such hormonally active compounds, known scientifically as endocrine disruptors, are currently the subject of intensive investigation by scientists from the Empa, among other research organizations. This work falls under the remit of the National Research Program 50 (“Endocrine Disruptors – Their Significance for Humans, Animals and Ecosystems”), which began in 2002. Over a score of research institutions are participating in this program, seeking the answers to such question as which substance are actually active as “environmental hormones”, in what concentrations are these chemicals found polluting various ecosystems and how much of them do humans and animals absorb?

Swiss lakes affected at different levels

For some years interest has been focused on the widely used UV filters 4-methylbenzylidene-camphor (4-MBC) und octocrylene (OC). Earlier studies of Lake Zurich and the Greifensee undertaken by the Agroscope FAW Waedenswil showed that sun blockers entered the water as a result of leisure activities such as swimming. As a result, concentrations in summer were significantly higher than in winter. In addition, lakes which were not used for bathing such as the secluded Joerisee above the Fluela pass showed hardly any pollution from these chemicals.

The concentrations found in the water was reflected in the quantities found in the lake’s inhabitants – the higher the level of UV filter compounds in the lake, the more of the substances found in the tissues of roach (Rutilus rutilus) and whitefish (Coregonus sp.).

Simultaneously, Empa scientists Martin Kohler und Peter Schmid were, in cooperation with the EAWAG, the Swiss Federal Institute of Aquatic Science and Technology, investigating the presence of brominated fire retardants in fish of various origins. These substances accumulate not just in fatty tissue, but also in mother’s milk. As they degrade very slowly they are classified as POPs (persistent organic pollutants). “The fish act as a kind of sampling device for us, giving us information on the levels of pollution in various aquatic ecosystems. Our main aim is to ensure that materials in widespread use are safe, or putting it another way to detect unsafe substances and, if possible, reduce their emissions,” explained Kohler.

Flame retardants, which are primarily used in plastic housings for electrical appliances and in upholstered furniture, were even found by the Empa team in the waters of secluded mountain lakes, and in the fish that were caught in them. Admittedly, the concentrations observed were lower than seen in lakes and rivers in inhabited areas. “The only possible way for these environmental pollutants to enter mountain lakes is by atmospheric transmission” according to Schmid.

Successful cooperation between several research institutes

In order to ascertain just how badly Swiss rivers (and the fish in them) are by polluted UV filters, the Empa researchers joined forces with their Agroscope colleagues. Schmid and Kohler, together with Eawag colleagues, had previously caught fish from seven rivers and tested their fat and muscle – the fillet – for various environmental pollutants as part of an NFP 50 project. Now the tissue extracts were analyzed for 4-MBC and OC in Waedenswil

In order to study the most highly affected fish, they were all caught within a few hundred meters downstream of  waste water treatment plants. The reason for this is that although most of the endocrine disruptors are broken down or immobilized by treatment plants, their outlets still represent the main sources of river pollution.

This was supported by the results of the chemical analysis. In comparison to the lake fish, brown trout (Salmo trutta fario) from Swiss rivers contained in some cases significantly higher quantities of 4-MBC and OC. Whereas roach and whitefish from the lakes showed concentrations of up to 170 ppb of 4-MBC (“parts per billion“, or nanograms per gram of fat), the brown trout had levels up to as much as 2400 ppb. The same tendency was found in the case of brominated flame retardants; brown trout showed much higher concentrations than fish from Swiss lakes.

In general however, the trend is downward. Since 2002 the level of 4-MBC pollution in national waters has been dropping. The reason for this is that endocrine disruptors are gradually being replaced by less harmful substances. “One thing that you absolutely must not do is stop using sun cream. Too much UV is dangerous” said Empa scientist Martin Kohler. But industry must exercise care in its choice of UV filters. Kohler again: “The idea is to avoid chemicals which accumulate in the environment and which could cause health problems.”

As a next step, Kohler and Schmid want to cast an eye on the UV filters which are added to certain plastics to protect them from deteriorating on exposure to sunlight. “Whether at all, and to what extent these substances cause pollution, is still completely unknown” comments Kohler.

Further information from:

Dr. Martin Kohler, Empa, Organic Chemistry Lab, +41 44 823 43 34, martin.kohler@empa.ch

Dr. Michael Hagmann, Empa, Communication Dept., +41 44 823 45 92, michael.hagmann@empa.ch