"Herbicide residues" refers to small amounts of chemicals left behind after using weed-killing substances. These remnants may be present on plants or in the soil and can have lasting effects on the environment. Full definition
Some of the concerns include an increase in allergies; an increase in herbicide residues in food; a worsening of antibiotic resistance in intestinal bacteria; reproductive problems; and genetic modification causing a plant to produce an unknown toxin which might have toxic effects on the body's organs. (womenshealthandfitness.com.au)
The reality is far worse as most of these vegetable oils are highly processed and grown as GMO crops, loaded with toxic herbicide residues like Roundup. (articles.mercola.com)
More importantly is that they still contain pesticide & herbicide residues once they hit the grocery store shelves. (eatlikethepros.com)