The white seeds indicate that the watermelon did not grow naturally. It should have used some kind of ripening substance or hormone. The most common ripening substance is ethylene. The sweet and fragrant taste of apples after being left for a long time is a manifestation of high ethylene content. Therefore, if you want to ripen some fruits at home, you can put apples and other fruits together. Therefore, it would be difficult to say if hormonal substances harmful to the body are used to accelerate ripening. If you are worried, you should wait until there are more watermelons before buying them.