Poisoning, either from naturally occurring or manmade chemicals, can result from ingestion, inhalation, or skin contact with the toxin. It can also be either acute (a one-time, high amount such as a drug overdose) or chronic (a smaller, amount over a long period of time, such as lead poisoning). Poison control centers in many countries can provide information on treatment and prevention of accidental poisoning from household or industrial products. There are more than 13 million known toxins, but less than 3,000 cause most incidents of poisoning. Several practices put in place since the 1950's have reduced accidental poisoning by ten-fold. These practices include the accurate labeling of potentially poisonous household compounds, and the use of monitoring devices such as carbon-monoxide detectors. One of the most successful prevention tactics is the use of child-resistant caps on containers of medicine and household products.