Calcium arsenate

Structural formula
General
Surname	Calcium arsenate
other names	Calcium orthoarsenate; Calcareous arsenic; arsenic calcium; Calcium arsenate;
Molecular formula	Ca 3 (AsO 4 ) 2
Brief description	colorless and odorless powder
External identifiers / databases
EC number	231-904-5
ECHA InfoCard	100.029.003
PubChem	24501
Wikidata	Q412645
properties
Molar mass	398.07 g mol −1
Physical state	firmly
density	3.62 g cm −3
Melting point	1455 ° C
boiling point	decomposes when heated
solubility	very heavy in water (130 mg l −1 )
safety instructions
H and P phrases	H: 301-331-350-410
	P: 261-281-301 + 310-321-405-501
Authorization procedure under REACH	particularly worrying : carcinogenic ( CMR )
MAK	DFG : none, as it is carcinogenic; Switzerland: 0.1 mg m −3 (based on arsenic, measured as inhalable dust );
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Calcium arsenate, or calcareous arsenic, was an important insecticide from 1918 to the 1960s . In the USA it was mainly used against the cotton boll beetle in cotton cultivation. In Germany, lime arsenic was mainly used in viticulture, but this use was banned in 1942 after numerous cases of poisoning.

history

United States

In 1918, calcium arsenate was discovered by entomologists at the Bureau of Entomology , a division of the US Department of Agriculture , for use against the cotton boll weevil ( Anthonomus grandis , English "boll weevil"). They had observed that the adult beetle covered its water needs with dew drops . The dew was poisoned by applying finely powdered calcium arsenate early in the morning. Most of the hibernating beetles were killed by initial treatment in spring, and further dusting kept the cotton boll beetle below the economic damage threshold . According to another source, calcium arsenate was used because during the First World War the prices of lead rose so much that the previously used lead hydrogen arsenate became too expensive. This method of chemical control was promoted by the Bureau of Entomology and quickly adopted by farmers. While only 50,000 pounds (about 23 tons) of calcium arsenate were sold in the USA in 1918, it was already ten million pounds (about 4,540 tons) in 1920 . Consumption then continued to rise, for example one of the first agricultural aviation companies applied the insecticide in 1927 on an area of over 2000 km² of cotton fields.

Calcium arsenate production in the USA
1931	1935	1937	1953	1957	1959
11,850 t	19,640 t	16,784 t	7,260 t	3,293 t	8,835 t

Germany

In Germany, arsenic-containing pesticides were not used until 1920 after they were included in the first list of pesticides by the Biological Reichsanstalt für Agriculture and Forestry . The main area of application was the control of the grape moth . In 1936, the Reichsliste of the tested preparations of the German Plant Protection Service contained, besides Schweinfurt green preparations, ten calcium arsenic sprays and six calcium arsenic dusts for pest control in viticulture. The first cases of arsenic poisoning occurred in 1925 at the Kaiserstuhl , and in 1929 the agricultural trade association recognized this poisoning as an occupational disease. By spring 1934 94 cases had been recognized, 66 of which had occurred in the Kaiserstuhl. It was initially assumed that this poisoning occurred primarily when calcareous arsenic dusts were applied. The use of arsenic-containing insecticides on the Moselle did not emerge until 1925; in 1930, their use was widespread there too. From 1938 onwards, cases of arsenic poisoning increased on the Moselle. In March 1940, the employers' liability insurance association recognized 589 cases of arsenic damage, and statistics were no longer published during the war. The number of cases of poisoning was estimated at around 800 to 1,000 in 1942. The cause was finally recognized as the pomace wine made by the winemakers as a house drink for their own use, which contained between 2 and 8.9 mg arsenic / l. The arsenic exposure lasted an average of 12 to 14 years, according to one estimate, a winemaker ingested around 53 g As ₂ O ₃ over this time , 47 g of which was attributed to the consumption of house drinks and only 6 g to the direct intake during the application . After an arsenic-free insecticide was successfully tested, the use of arsenic-containing agents in viticulture was banned by a law of November 26, 1942. Other uses of arsenic-containing pesticides were only banned in the Federal Republic of Germany in 1974.

toxicology

The acute oral LD ₅₀ for the rat is 20 mg / kg body weight.

Ecotoxicology

Water-soluble arsenic compounds like calcium arsenate can also damage plants. The leaves of stone fruit species are particularly sensitive. Calcium arsenate is dangerous for bees and highly toxic for fish. Inorganic arsenic compounds remain in the soil for a long time.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on calcium arsenate in the GESTIS substance database of the IFA , accessed on February 22, 2017(JavaScript required) .
↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry arsenic compounds, with the exception of those named in this appendix in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Entry in the SVHC list of the European Chemicals Agency , accessed on July 17, 2014.
↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 7778-44-1 or calcium arsenate ), accessed on October 24, 2016.
↑ ^a ^b ^c Thomas R. Dunlap: DDT: Scientists, Citizens and Public Policy . Princeton University Press, 1981, ISBN 0-691-04680-8
↑ Francis J. Peryea: Historical use of lead arsenate insecticides, Resulting soil contamination and implications for soil remediation ( Memento of 7 December 2008 at the Internet Archive ). Proceedings, 16th World Congress of Soil Science (CD Rom), Montpellier, France, 20. – 26. Aug 1998
^ Paul Claus: Arsenic for pest control in viticulture 1904-1942 . Writings on wine history, No. 58, Wiesbaden 1981, ISSN 0302-0967
↑ ^a ^b Werner Perkow: Active substances in pesticides and pesticides . 2nd edition, Paul Parey publishing house

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on calcium arsenate in the GESTIS substance database of the IFA , accessed on February 22, 2017(JavaScript required) .

[CLP_100.240.769-2] Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry arsenic compounds, with the exception of those named in this appendix in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[SVHC-3] Entry in the SVHC list of the European Chemicals Agency , accessed on July 17, 2014.

[4] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 7778-44-1 or calcium arsenate ), accessed on October 24, 2016.

[Dunlap-5] Thomas R. Dunlap: DDT: Scientists, Citizens and Public Policy . Princeton University Press, 1981, ISBN 0-691-04680-8

[Peryea-6] Francis J. Peryea: Historical use of lead arsenate insecticides, Resulting soil contamination and implications for soil remediation ( Memento of 7 December 2008 at the Internet Archive ). Proceedings, 16th World Congress of Soil Science (CD Rom), Montpellier, France, 20. – 26. Aug 1998

[Claus-7] Paul Claus: Arsenic for pest control in viticulture 1904-1942 . Writings on wine history, No. 58, Wiesbaden 1981, ISSN 0302-0967

[Perkow-8] Werner Perkow: Active substances in pesticides and pesticides . 2nd edition, Paul Parey publishing house