Pencil thereby pushing a new tip to the top. Invented by Harold Grossman for Empire Pencil Company in 1967 and subsequently improved upon by Arthur D. Little for Empire from 1969 through the early 1970s; the plastic pencil was commercialised by Empire as the "EPCON" Pencil. These pencils were co-extruded, extruding a plasticised graphite mix within a wood-composite core. Residual graphite from a pencil stick is not poisonous, and graphite is harmless if consumed. Although lead has not been used for writing since antiquity, lead poisoning from pencils was not uncommon. Until the middle of the 20th century the paint used
Lead poisoning with lead in air, household dust, soil, water, and commercial products. Leaded gasoline has also been linked to increases in lead pollution. Some research has suggested a link between leaded gasoline and crime rates. Man made lead pollution has been elevated in the air for the past 2000 years. Lead pollution in the air is entirely due to human activity (mining and smelting). In adults, occupational exposure is the main cause of lead poisoning. People can be exposed when working in facilities that produce a variety of lead-containing products; these include radiation shields, ammunition, certain surgical equipment, developing dental x-ray