This common, popular vegetable is often eaten raw. It is subject to damage from the fruit borer family, as in the case of brinjal. Since both tomato and brinjal have shiny skins, external application of pesticide may not be effective. Farmers therefore use what are called 'systemic insecticides'. (Systemic or system-wide, refers to something that affects as a whole.) In fact, most companies are now largely promoting systemic pesticides. These enter the entire plant through the stomata, contaminating the tomato from within. No amount of washing of the vegetable will get rid of it.
The chemicals very commonly used are called organophosphates. One graphic study from the United States showed that children of farmers who used these had smaller brains and were slow learners compared to those not exposed. Organophosphates are neural poisons.