#0123 ‘Exposing’ Environmental Chemicals in Biologic Specimens: A New Approach

‘Exposing’ Environmental Chemicals in Biologic Specimens: A New Approach

Humans and other organisms are constantly exposed to different chemicals in the environment around them. These affect an organism’s gene expression and alter major bodily functions in the long term. They are, often, the unexplained underlying causes of various diseases.

Several studies have attempted to identify these chemicals both in the environment and the human body. Researchers are also trying to collate existing information and build a database of all possible such chemicals and their metabolites in our bodies (the ‘exposome’). However, in this endeavor they face a number of challenges.

Due to a lack of existing technology or methods to measure the exposome and analyze new chemicals, studying them on an epidemiological level is difficult; researchers have, so far, only managed to study a few chemicals in small target groups. Further, any large-scale reference databases created for studying metabolites in our bodies have focused only on naturally occurring ones, and not those of chemicals from the environment.

Thus, a group of researchers from Japan aimed to bridge these gaps by developing a method of comprehensive analysis that could both monitor environmental chemicals in humans and be applied to epidemiological studies.

As a first step in that direction, they analysed 73 human urine samples using a technique called liquid chromatography–high resolution mass spectrometry to detect the presence and amounts of potential metabolites.

They then compared the detected substances with two databases: an existing reference dataset of common organophosphate pesticides and a new dataset that they had created from animal experiments in mice fed with these pesticides.

With the reference dataset, they were able to identify only one metabolite of one organophosphate pesticide called prothiofos. But with the new database, they successfully identified three metabolites of prothiofos. Prothiofos is widely used for the cultivation of various crops (including soybean, potato, and onion) in Japan, making the appearance of its metabolites in their urine highly plausible.

Thus, their new method successfully identified urinary compounds that suggest exposure to prothiofos which, despite its common use, has not been part of human biomonitoring studies. This strategy of creating a database from animal experiments could offset the inadequacy of existing human metabolite reference databases and be applied to identifying metabolites of a wide range of environmental chemicals of concern. This will, ultimately, help us identify potential environmental hazards and build a safer world.

Link to the original journal article:
https://academic.oup.com/joh/article/63/1/e12218/7249845

Title of the paper:
Development of a strategic approach for comprehensive detection of organophosphate pesticide metabolites in urine: Extrapolation of cadusafos and prothiofos metabolomics data of mice to humans

Authors:
Karin Nomasa, Naoko Oya, Yuki Ito, Takehito Terajima, Takahiro Nishino, Nayan Chandra Mohanto, Hirotaka Sato, Motohiro Tomizawa, Michihiro Kamijima

DOI:
10.1002/1348-9585.12218