The number of chemical structures known to us is expanding exponentially. For example, PubChem currently includes more than 115 million unique structures, and this number is growing. Even though these numbers may seem large, compared to the true size of the chemical space -more than 10 60 for structures smaller than 500 Da -these lists cover less than 0.001% of the chemical space. Furthermore, for the known structures less than 1% of them have been experimentally evaluated for their environmental and biological activity (e.g. toxicity), due to the cost and complexities associated with such measurements. Several studies have shown the negative impact of exposure to chemicals with long-term adverse health outcomes. For example, the exposure to PFAS has been shown to correlate with autoimmune problems as well as mental health issues. Therefore, to be able to safeguard environmental and human health, comprehensive mapping of the boundaries of the exposome chemical space is urgently needed.