Public health officials plan to knock on the doors of homes in the East Trenton neighborhood to offer testing for children, after three parks and a city school there tested positive for high lead levels recently. Trenton Mayor Reed Gusciora announced in January that the U.S. Environmental Protection Agency (EPA) found lead in Grant intermediate school and in April, three parks: Sony (also spelled Sonny) Vereen Playground, Breunig Avenue Park, and Grant Avenue Playground. The EPA is coordinating cleanup, and the city wants to test the 600 students at Grant. So far, though, only 118 of them have…