How to trust the data provided in a blockchain focused on process chain control?

For example, in the food industry I saw several cases that want to track the entire food production process. How can one trust the information they aggregate?

For example, I say that my wheat has this chemicals and nothing else, that I do not supply it with any agro-toxins. How do I validate that this is true? I would have to provide a scientific study, and I would have to trust the laboratory not to lie in the results?

This applied beyond the food industry, how can you be certain that what you are supplying is valid? Example I want to store something important that has to be valid and not falsified. How can we avoid that our blockchain or our contract becomes an accumulation of falsified things?

Thank you very much!