Both my mother and father had Alzheimers. They didn't have their lawn treated. I treated it a few times only after they went to a nursing home. Be sure to have the MSDS sheet for your products. Be sure to point out that urea is a product found in urine in every human being and animal on earth. Potassium, too. Be sure to contact you fertilizer dealer for their experts. They will put you in touch with the manufacturer which can provide more data. Be sure to mention that all pesticides sold in the US are tested by laboratories for hundreds of hours in every way possible. Several generations of rates at very high levels.