Lead to that of primary lead; some refining processes may be skipped depending on the material recycled and its potential contamination. Of the sources of lead for recycling, lead–acid batteries are the most important; lead pipe, sheet, and cable sheathing are also significant. Contrary to popular belief, pencil leads in wooden pencils have never been made from lead. When the pencil originated as a wrapped graphite writing tool, the particular type of graphite used was named "plumbago" (literally, "act for lead" or "lead mockup"). Lead metal has several useful mechanical properties, including high density, low melting point, ductility, and relative inertness.
Lead poisoning affected by lead toxicity to varying degrees depending on species. Animals experience many of the same effects of lead exposure as humans do, such as abdominal pain, peripheral neuropathy, and behavioral changes such as increased aggression. Much of what is known about human lead toxicity and its effects is derived from animal studies. Animals are used to test the effects of treatments, such as chelating agents, and to provide information on the pathophysiology of lead, such as how it is absorbed and distributed in the body. Farm animals such as cows and horses as well as pet animals are also