Imagine you want to poison a population, but you can't obviously send a poison in a single product or food because it would eventually be discovered if everyone eating or using that one product all got sick. Instead, what China does is divide a poison into multiple component parts sometimes using sophisticated genetic engineering (like crispr) to make the components last much longer than usual in the body, so that instead of the poison being contained in one food or product, it's components are contained across two or more products, which when combined in or on the body at the same time, form the poison. That way it's MUCH MUCH harder to detect because analyzing a single product would yield no obvious poison and also gives them plausible deniability ("oh, we didn't realize those two products together would be deadly or cause cancer!! we swear!"). All they have to do is spread the poison across multiple products they know the majority of the population uses such as vitamins, body creams or lotions, and a popular food or drink like soda, and boom, they can poison the majority of the population while being incredibly difficult to discover and making it INCREDIBLY DIFFICULT to prove nefarious intent without a whistleblower on the inside of their operation (inside their military basically) because they can split distribution points of the poison components across multiple different front companies within China. And even more difficult if they stagger the inclusion of the poison components in those products so they don't appear in every single shipment. That alone would make it damn near impossible without considerable resources and money to detect. Binary bio is full-on 5th generation warfare because it's both incredibly difficult to discover and even more difficult to prove responsibility. So when China said "unrestricted warfare", they weren't kidding.