This advice came from the Federal Ministry of Health. "Basically, people should only eat washed vegetables and fruits." This statement was from a 1980 report titled "Heavy Metal Elements in Food and on the Surface of Fruits." The report concluded: "Through careful washing, the lead content of this type of food is significantly reduced." In another issue of the "Federal Health Report," it was stated: "Through washing, the lead content in food can be reduced by 50%."
This advice was quite clever. The idea that environmental problems could be solved by "careful washing" only shows that Germans at that time were very "logical." Five years later, the newly founded environmental magazine "Öko-Test" began to refute this view: "Washing apples: useless." In a detailed study, the Bremen Institute for Environmental Research found that about half of the lead exists in the flesh under the skin and in the core, making any amount of washing useless. For Golden Delicious apples, careful washing in cold water and a quick rinse in hot water were equally effective in removing pesticide residues from the surface. Only for the rough-skinned Boskoop apples could washing with a brush minimize the amount of lead residue on the surface. For Golden Delicious apples, the most effective cleaning method is: to rub vigorously with a dry cloth until it shines.
In summary, it can be seen that due to the nature of fruit skins, pesticide residues and environmental pollutants are not easily washed off. Both substances exist on top of the cuticle and are stuck to it like wax. Therefore, washing with water is not effective. The best way to remove them is to act like those mischievous children: rub back and forth on clothes.