London: Certain fragrances widely used in soaps, detergents, shampoos and many other personal hygiene products may potentially contaminate the environment, a pioneering new study on the canals of Venice has found.

Researchers, including those at the Ca’ Foscari University of Venice in Italy, have been investigating the canals to look for traces of these molecules which are referred to as ‘perfumes’ in the ingredients of products that we use daily.

Soaps, detergents, shampoos and many other personal hygiene products contain mixtures of ‘odorous’ molecules that have passed safety tests for human health with little or nothing known about their impact on the environment.

Between April and December last year, scientists repeatedly collected water samples from 22 places between the inner canals in the historic centre of Venice, the island of Burano and at two points in the far-north lagoon.

They were looking for the presence of 17 fragrances among the most used and chemically stable between the thousands available to the cosmetics industry. Samples collected during conditions of low tide in Venice and Burano showed concentrations comparable to those of untreated waste water.

In Venice, the city without sewers, wastewater treated through biological tanks which then flow directly into the canals thus seems an insufficient method of lowering the concentration of these molecules, researchers said.

For example, one of the most frequently found compounds in the waters of the lagoon was benzyl salicylate, a known allergenic which has to be indicated on the labels of cosmetic products which contain it.

Ours is a pioneering study on the persistence of a new class of potential contaminants in the environment, said Marco Vecchiato from Ca’ Foscari.

After this first analysis, we can confirm that fragrances are released continuously into the canals of Venice, both during high and low tide and both in the historic centre and the lagoon.

According to our data, however, the concentrations seem to be below the threshold for acute toxicity to marine organisms. That being said, we do not know the consequences of prolonged exposure to low doses of these substances. This study is thus the first step in gauging an understanding of its environmental fate, said Vecchiato.