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"Poisonous" does not mean deadly. Some manifestations of toxicity are subtle. The dose, as always, determines if a plant is safe source of nutrients or a toxic hazard.

Lead Poisoning

This page provides information on lead poisioning in humans as well as domestic animal populations. Sections include sources of lead in houses and barns, environmental contamination and some of its' causes, toxic levels in children and animals, symptoms of toxicity and links to related sites of information.

With the relatively recent restrictions on the use of lead based paints, one of the largest sources of lead poisioning has been greatly reduced. These paints are still present in houses, garages, barns, on fences and furniture. The prevalence of lead in the world around us is still a significant health hazard, especially to certain "at risk" portions of human and animal populations. Although adults are susceptible to lead poisoning, children and newborns are most susceptible because of lower tolerance levels and the tendency to introduce foreign objects into the body.

Sources In the Home

  • Lead-Based Paint-Present on many surfaces in homes not recently rebuilt or remodeled
  • Lead Pipes-More common in older homes
  • Lead Solder -On pipes and water heaters
  • Enameled or Ceramic Pots and Dishware-Improper glazing can leech lead into foods
  • Paper Wrappings-Holiday paper and party decorations (10g/kg)
  • Food Packages-Polythene plastic bags, flour bags(20mg/kg),cardboard boxes with dyes (50mg/kg)
  • Candy Packaging-Candy bar wrappers(7g/kg), Colored sports trading cards packaged with gum(88mg/kg)

Although lead paint chips are still the most common source of acute lead poisoning, candy wrappers and food packaging are of particular concern because they are in direct contact with immediately consumed items. It is important to keep these items from being consumed, chewed or licked.

Pathways of lead from the environment to man, and body disposition of lead.

Environmental Contamination

  • Mining-All types of mining industries, especially strip mining can cause lead and other minerals to leech into ground water, soil and even into the air as dust particles.
  • Steel Industry-Any company that produces steel or uses steel in production can contribute to the bioaccumulation of lead in soil, water and air.
  • Crop Enhancers-Many crop yields are increased with the use of fertilizers, fungicides and herbicides that contain appreciable amounts of lead (e.g. lead arsenate)
  • Automobiles-Lead is added to some gasoline as an anti-knock agent and lead is emitted in motor vehicle exhaust.
  • Batteries-Improper disposal of batteries from automobiles, electric vehicles and emergency lighting systems>
  • Rogue Metal-Parts of Farm Machinery, Mining Machinery, Food Processing Equipment or other metal objects that can break and leave pieces or shavings where they may leech into food or the environment.

Toxic Levels In Children

The blood concentrations and classes of poisoning are adapted from CDC literature "Preventing Lead Poisoning in Young Children" published in October 1991.

Toxic Levels In Animals

  • Cattle-Intakes of greater then 6 mg/kg body weight can lead to chronic poisoning and intakes greater than 10 mg/kg BW may cause acute lead poisoning.
  • Sheep-Generally occurs only in lambs and symptoms of poisoning appear at intakes greater than 4.5 mg/kg BW.
  • Pigs, Goats and Rabbits-More resistant than sheep or cows. Very minor signs of poisoning occur at intakes of 60 mg/kg BW. This is equal to blood concentrations of 130 micrograms per dl.
  • Horses-Respiratory "roaring" occurs at intakes of 6.4 mg/kg BW. Signs of anemia occur at intakes of 7.4 mg/kg.
  • Birds-Poultry can withstand dietary intakes of 100 mg/kg feed with no symptoms. Levels of 500 mg/kg induced serious poisoning.
  • Dogs and Cats-Nervous symptoms of poisoning appear at intakes of 5 mg/kg BW/day.

Symptoms of Toxicity

The general symptoms of lead poisoning are universal although more information is available on poisoning in humans. The first symptoms of lead toxicity are very general and nonspecific. These include nausea, sluggishness, vomiting, painful gastrointestinal irritation, diarrhea, loss of appetite, colic, weakness and dehydration. These symptoms are common to many disorders and can often lead to inaccurate diagnosis.

Some symptoms more specific to human poisoning include discoloration of the lips and skin attributed mild secondary anemia, a lead line on the gums, developmental disorders, sterility and abortion. There have also been some prelimiunary reports indicating that chronic lead poisoning can also lead to chronic nephritis and premature development of arteriosclerosis.

More severe cases of poisoning can produce symptoms including convulsions,"wrist drop" or external limb paralysis, coma and ultimately death.


National Lead Information Center (800) LEAD-FYI Great source of information including pamphlet "Lead Poisoning and Your Children"

U.S. EPA-Office of Pollution Prevention and Topics