Lead hydrogen arsenate
Encyclopedia
Lead hydrogen arsenate, also called lead arsenate, acid lead arsenate or LA, chemical formula PbHAsO4, is an inorganic insecticide
used primarily against the potato beetle.
Lead arsenate was the most extensively used arsenic
al insecticide. According to the preceding reference, two (2) principal formulations of lead arsenate were marketed; basic lead arsenate (Pb5OH(AsO4)3, CASN: 1327-31-7) and acid lead arsenate (PbHAsO4, CASN: 7784-40-9).
Until 1930s-1940s, lead arsenate was frequently prepared by farmers at home, by reacting soluble lead
salts with sodium arsenate.
in Massachusetts
, as a less soluble and less toxic alternative to then-used Paris Green
. It also adhered better to the surface of the plants, further enhancing and prolonging its insecticidal effect.
Lead arsenate was widely used in Australia
, Canada
, New Zealand
, USA, England
, France
, North Africa
, and many other areas, principally against the codling moth
. It was used mainly on apple
s, but also on other fruit trees, garden crops, turfgrasses, and against mosquito
es. In combination with ammonium sulfate
, it was used in southern California
as a winter treatment on lawns to kill crab grass seed.
Lead arsenate was also used in the early part of twentieth century for controlling pests of cranberry (fireworm, cranberry girdler) in Massachusetts.
Basic lead arsenate, Pb5OH(AsO4)3, was used in some areas of California.
The search for a substitute was commenced in 1919, when it was found that its residues remain in the products despite washing their surfaces. Alternatives were found to be less effective or more toxic to plants and animals, until 1947 when DDT
was found. The use of lead arsenate in the USA continued until the mid-1960s. It was officially banned as an insecticide on August 1, 1988.
Morel mushrooms growing in old apple
orchard
s that had been treated with lead arsenate may accumulate
levels of toxic lead
and arsenic
that are unhealthy for human consumption.
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
used primarily against the potato beetle.
Chemistry
It is usually produced using the following reaction:- Pb(NO3)2(aq) +H3AsO4(aq) → PbHAsO4(s) +2HNO3(aq)
Lead arsenate was the most extensively used arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
al insecticide. According to the preceding reference, two (2) principal formulations of lead arsenate were marketed; basic lead arsenate (Pb5OH(AsO4)3, CASN: 1327-31-7) and acid lead arsenate (PbHAsO4, CASN: 7784-40-9).
Until 1930s-1940s, lead arsenate was frequently prepared by farmers at home, by reacting soluble lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
salts with sodium arsenate.
Uses
As an insecticide, it was first used against the gypsy mothGypsy moth
The gypsy moth, Lymantria dispar, is a moth in the family Lymantriidae of Eurasian origin. Originally ranging from Europe to Asia, it was introduced to North America in the late 1860s and has been expanding its range ever since...
in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
, as a less soluble and less toxic alternative to then-used Paris Green
Paris Green
Paris Green is an inorganic compound more precisely known as copper acetoarsenite. It is a highly toxic emerald-green crystalline powder that has been used as a rodenticide and insecticide, and also as a pigment, despite its toxicity. It is also used as a blue colorant for fireworks...
. It also adhered better to the surface of the plants, further enhancing and prolonging its insecticidal effect.
Lead arsenate was widely used in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, USA, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
, and many other areas, principally against the codling moth
Codling moth
The codling moth is a member of the Lepidopteran family Tortricidae. They are known as an agricultural pest, their larva being the common apple worm or maggot. It is native to Europe and was introduced to North America, where it has become one of the regular pests of apple orchards. It is found...
. It was used mainly on apple
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
s, but also on other fruit trees, garden crops, turfgrasses, and against mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
es. In combination with ammonium sulfate
Ammonium sulfate
Ammonium sulfate , 2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen as ammonium cations, and 24% sulfur as sulfate anions...
, it was used in southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
as a winter treatment on lawns to kill crab grass seed.
Lead arsenate was also used in the early part of twentieth century for controlling pests of cranberry (fireworm, cranberry girdler) in Massachusetts.
Basic lead arsenate, Pb5OH(AsO4)3, was used in some areas of California.
The search for a substitute was commenced in 1919, when it was found that its residues remain in the products despite washing their surfaces. Alternatives were found to be less effective or more toxic to plants and animals, until 1947 when DDT
DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
was found. The use of lead arsenate in the USA continued until the mid-1960s. It was officially banned as an insecticide on August 1, 1988.
Morel mushrooms growing in old apple
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
orchard
Orchard
An orchard is an intentional planting of trees or shrubs that is maintained for food production. Orchards comprise fruit or nut-producing trees which are grown for commercial production. Orchards are also sometimes a feature of large gardens, where they serve an aesthetic as well as a productive...
s that had been treated with lead arsenate may accumulate
Bioaccumulation
Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost...
levels of toxic lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
and arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
that are unhealthy for human consumption.