Geogenic contamination - Arsenic - Revision history

Gap: Protected "Geogenic contamination - Arsenic" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

2018-05-10T11:01:42Z

Protected "Geogenic contamination - Arsenic" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

Gap at 03:19, 25 September 2026

Gap: Protected "Geogenic contamination - Arsenic" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

Protected "Geogenic contamination - Arsenic" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

Gap at 03:19, 25 September 2026

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-''NOTE: Article from the Geogenic Contamination Handbook''
+''NOTE: Modified article from the Geogenic Contamination Handbook''
 == Occurrence ==
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 == Health effects ==
-[[File:Figure 2.3.jpg|thumb|left|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning ''(Terms of use - Cite original source from Handbook)'']][[File:Figure 2.4.jpg|thumb|left|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. ''(Terms of use - Cite: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007))'' ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
+[[File:Figure 2.3.jpg|thumb|right|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning ''(Terms of use - Cite original source from Handbook)'']][[File:Figure 2.4.jpg|thumb|right|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. ''(Terms of use - Cite: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007))'' ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
 The first obvious symptoms are often skin lesions (keratosis, melanosis; Fig. 2.3), but other effects can include weakness, diarrhoea, bronchitis, vascular disease and diabetes mellitus (UNICEF/Chinese Ministry of Health, 2004).
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 ==References==
 For references, please visit the page [[References - Geogenic Contamination Handbook]].

← Older revision		Revision as of 03:19, 25 September 2026
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	[[File:Figure 2.2.jpg\|600px\|thumb\|right\| Fig. 2.2 Modelled global probability of elevated geogenic arsenic concentrations in groundwater ''(Terms of use: Cite original source: Amini et al., 2008a)'']] Arsenic in drinking water is a global threat to health, potentially affecting about 140 million people in at least 70 countries worldwide (Ravenscroft et al., 2009). It is considered by some researchers to have more serious health effects than any other environmental contaminant (Smith and Steinmaus, 2009).		[[File:Figure 2.2.jpg\|600px\|thumb\|right\| Fig. 2.2 Modelled global probability of elevated geogenic arsenic concentrations in groundwater ''(Terms of use: Cite original source: Amini et al., 2008a)'']] Arsenic in drinking water is a global threat to health, potentially affecting about 140 million people in at least 70 countries worldwide (Ravenscroft et al., 2009). It is considered by some researchers to have more serious health effects than any other environmental contaminant (Smith and Steinmaus, 2009).

−	Drinking water can contain arsenic at concentrations of up to several mg/L, most commonly as the reduced species, As(III) (arsenite), or the oxidised species, As(V) (arsenate). As(III) is uncharged (H3AsO3) under ambient pH conditions, and as such, is more mobile than As(V) (H2AsO4- or HAsO42-). Under most geochemical conditions, arsenic in aquifers remains tightly bound to the sediments, and concentrations ~~of dissolved arsenic~~ in the groundwater remain low. However, ~~two geochemical conditions have been identified under which~~ elevated concentrations of arsenic can be found ~~in the groundwater~~ even when solid-phase concentrations in the sediments are unremarkable: reducing conditions in ~~young alluvial aquifers~~ and ~~arid, high pH oxidising conditions~~ in rocks ~~and~~/or sediments with ~~relatively low permeability~~ (Smedley and Kinniburgh, 2002). Figure 2.2 shows the modelled probability of the occurrence of geogenic arsenic contamination in groundwater for both of these conditions combined. Geothermal contributions and sulphide oxidation in ~~mine tailings~~ can also lead to elevated arsenic concentrations in groundwater, but these conditions tend to be more localised and have not been included in the model.	+	Under most geochemical conditions, arsenic in aquifers remains tightly bound to the sediments, and dissolved concentrations in the groundwater remain low. However, elevated concentrations of arsenic in groundwater can be found even when solid-phase concentrations in the sediments are unremarkable. (It is the 55th most abundant element in the Earth’s crust with an average content of 1.8 mg/kg). Such sediments are typically young and contain organic carbon that can be consumed by microbes. Microbes use oxygen or other oxidants present and create chemically reducing conditions in which reduced species, such as arsenic (arsenite, As(OH)3), iron (Fe(II)) and manganese (Mn(II)) predominate. Groundwater in low-permeable host rocks/sediments with chemically oxidising conditions, high pH and generally arid conditions may also be contaminated, though to a lesser degree (Smedley and Kinniburgh, 2002). Figure 2.2 shows the modelled global probability of the occurrence of geogenic arsenic contamination in groundwater for both of these conditions combined. Geothermal contributions and sulphide oxidation from sulphide minerals in host rocks can also lead to elevated arsenic concentrations in groundwater, but these conditions tend to be more localised and have not been included in the model.

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 == Occurrence ==
-[[File:Figure 2.2.jpg|600px|thumb|right| Fig. 2.2 Modelled global probability of elevated geogenic arsenic concentrations in groundwater (Cite original source: Amini et al., 2008a)]] Arsenic in drinking water is a global threat to health, potentially affecting about 140 million people in at least 70 countries worldwide (Ravenscroft et al., 2009). It is considered by some researchers to have more serious health effects than any other environmental contaminant (Smith and Steinmaus, 2009).
+[[File:Figure 2.2.jpg|600px|thumb|right| Fig. 2.2 Modelled global probability of elevated geogenic arsenic concentrations in groundwater ''(Terms of use: Cite original source: Amini et al., 2008a)'']] Arsenic in drinking water is a global threat to health, potentially affecting about 140 million people in at least 70 countries worldwide (Ravenscroft et al., 2009). It is considered by some researchers to have more serious health effects than any other environmental contaminant (Smith and Steinmaus, 2009).
 Drinking water can contain arsenic at concentrations of up to several mg/L, most commonly as the reduced species, As(III) (arsenite), or the oxidised species, As(V) (arsenate). As(III) is uncharged (H3AsO3) under ambient pH conditions, and as such, is more mobile than As(V) (H2AsO4- or HAsO42-). Under most geochemical conditions, arsenic in aquifers remains tightly bound to the sediments, and concentrations of dissolved arsenic in the groundwater remain low. However, two geochemical conditions have been identified under which elevated concentrations of arsenic can be found in the groundwater even when solid-phase concentrations in the sediments are unremarkable: reducing conditions in young alluvial aquifers and arid, high pH oxidising conditions in rocks and/or sediments with relatively low permeability (Smedley and Kinniburgh, 2002). Figure 2.2 shows the modelled probability of the occurrence of geogenic arsenic contamination in groundwater for both of these conditions combined. Geothermal contributions and sulphide oxidation in mine tailings can also lead to elevated arsenic concentrations in groundwater, but these conditions tend to be more localised and have not been included in the model.
@@ Line 12: / Line 12: @@
 == Health effects ==
-[[File:Figure 2.3.jpg|thumb|left|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning (Terms of use: Cite original source.)]][[File:Figure 2.4.jpg|thumb|left|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. (Cite: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007)) ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
+[[File:Figure 2.3.jpg|thumb|left|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning ''(Terms of use - Cite original source from Handbook)'']][[File:Figure 2.4.jpg|thumb|left|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. ''(Terms of use - Cite: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007))'' ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
 The first obvious symptoms are often skin lesions (keratosis, melanosis; Fig. 2.3), but other effects can include weakness, diarrhoea, bronchitis, vascular disease and diabetes mellitus (UNICEF/Chinese Ministry of Health, 2004).

@@ Line 1: / Line 1: @@
 == Occurrence ==
-[[File:Figure 2.2.jpg|600px|thumb|right| Fig. 2.2 Modelled global probability of elevated geogenic arsenic concentrations in groundwater (Amini et al., 2008a)]] Arsenic in drinking water is a global threat to health, potentially affecting about 140 million people in at least 70 countries worldwide (Ravenscroft et al., 2009). It is considered by some researchers to have more serious health effects than any other environmental contaminant (Smith and Steinmaus, 2009).
+[[File:Figure 2.2.jpg|600px|thumb|right| Fig. 2.2 Modelled global probability of elevated geogenic arsenic concentrations in groundwater (Cite original source: Amini et al., 2008a)]] Arsenic in drinking water is a global threat to health, potentially affecting about 140 million people in at least 70 countries worldwide (Ravenscroft et al., 2009). It is considered by some researchers to have more serious health effects than any other environmental contaminant (Smith and Steinmaus, 2009).
 Drinking water can contain arsenic at concentrations of up to several mg/L, most commonly as the reduced species, As(III) (arsenite), or the oxidised species, As(V) (arsenate). As(III) is uncharged (H3AsO3) under ambient pH conditions, and as such, is more mobile than As(V) (H2AsO4- or HAsO42-). Under most geochemical conditions, arsenic in aquifers remains tightly bound to the sediments, and concentrations of dissolved arsenic in the groundwater remain low. However, two geochemical conditions have been identified under which elevated concentrations of arsenic can be found in the groundwater even when solid-phase concentrations in the sediments are unremarkable: reducing conditions in young alluvial aquifers and arid, high pH oxidising conditions in rocks and/or sediments with relatively low permeability (Smedley and Kinniburgh, 2002). Figure 2.2 shows the modelled probability of the occurrence of geogenic arsenic contamination in groundwater for both of these conditions combined. Geothermal contributions and sulphide oxidation in mine tailings can also lead to elevated arsenic concentrations in groundwater, but these conditions tend to be more localised and have not been included in the model.
@@ Line 11: / Line 12: @@
 == Health effects ==
-[[File:Figure 2.3.jpg|thumb|left|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning]][[File:Figure 2.4.jpg|thumb|left|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. Source: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007) ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
+[[File:Figure 2.3.jpg|thumb|left|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning (Terms of use: Cite original source.)]][[File:Figure 2.4.jpg|thumb|left|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. (Cite: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007)) ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
 The first obvious symptoms are often skin lesions (keratosis, melanosis; Fig. 2.3), but other effects can include weakness, diarrhoea, bronchitis, vascular disease and diabetes mellitus (UNICEF/Chinese Ministry of Health, 2004).

← Older revision		Revision as of 03:19, 25 September 2026
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	==References==		==References==
−	* For references, please visit the page [[References - Geogenic Contamination Handbook]].	+	For references, please visit the page [[References - Geogenic Contamination Handbook]].

← Older revision	Revision as of 11:01, 10 May 2018
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← Older revision		Revision as of 03:19, 25 September 2026
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	Because of the ongoing uncertainty about low-level effects and the difficulties involved in measuring arsenic concentrations below 10 µg/L or in reducing arsenic concentrations to this level, the WHO has set 10 µg/L as a provisional guideline value (WHO, 2011). Many countries have a less strict drinking-water standard of 50 µg/L. The disease burden at these levels can be considerable; Argos et al. (2010) found all-cause mortality levels to be 34% higher in a population exposed to 0.01–50 µg/L arsenic, compared to a control group with <10 µg/L exposure. Those exposed to 150 µg/L or more showed 68% higher all-cause mortality.		Because of the ongoing uncertainty about low-level effects and the difficulties involved in measuring arsenic concentrations below 10 µg/L or in reducing arsenic concentrations to this level, the WHO has set 10 µg/L as a provisional guideline value (WHO, 2011). Many countries have a less strict drinking-water standard of 50 µg/L. The disease burden at these levels can be considerable; Argos et al. (2010) found all-cause mortality levels to be 34% higher in a population exposed to 0.01–50 µg/L arsenic, compared to a control group with <10 µg/L exposure. Those exposed to 150 µg/L or more showed 68% higher all-cause mortality.
	There is no effective medical treatment for chronic arsenicosis, except for switching to an arsenic-free drinking-water source. However, palliative care such as application of ointments to cracked skin lesions can ease suffering. Chelation therapy is effective for short-term, acute poisoning, but not for long-term exposure.		There is no effective medical treatment for chronic arsenicosis, except for switching to an arsenic-free drinking-water source. However, palliative care such as application of ointments to cracked skin lesions can ease suffering. Chelation therapy is effective for short-term, acute poisoning, but not for long-term exposure.
		+
		+	==References==
		+	* For references, please visit the page [[References - Geogenic Contamination Handbook]].

@@ Line 11: / Line 11: @@
 == Health effects ==
-[[File:Figure 2.3.jpg|thumb|400px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
+[[File:Figure 2.3.jpg|thumb|left|450px|Fig. 2.3 Skin lesions (keratosis, melanosis) indicating arsenic poisoning]][[File:Figure 2.4.jpg|thumb|left|450px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. Source: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007) ]]Arsenic causes a wide range of adverse health effects. The acute toxicity of As(III) is somewhat greater than that of As(V), but because As(V) is reduced to As(III) in the body, the two species can be considered equally toxic.
 The first obvious symptoms are often skin lesions (keratosis, melanosis; Fig. 2.3), but other effects can include weakness, diarrhoea, bronchitis, vascular disease and diabetes mellitus (UNICEF/Chinese Ministry of Health, 2004).
 The main health concerns, however, are cancers of the skin or internal organs. In particular, arsenic-related lung and bladder cancers can cause heavy mortality (Argos et al., 2010; Sohel et al., 2009). More recently, arsenic exposure has been linked to cardiac effects such as myocardial infarction (heart attacks) (Yuan et al., 2007). Cardiac risks are elevated within short exposure periods, while cancers can take decades to develop, even long after arsenic exposure has stopped (Fig. 2.4). In addition, arsenic is linked with a range of impacts on children, including reduced birth weight, infant mortality and impaired cognitive development (Smith and Steinmaus, 2009).
-[[File:Figure 2.4.jpg|thumb|400px|Fig. 2.4 Latency of cancer and heart disease in northern Chile. Drinking water contained approximately 800 µg/L arsenic from 1958–1971, after which an arsenic removal plant greatly reduced exposure. Source: Redrawn by Ravenscroft et al. (2009) after Yuan et al. (2007) ]]Because of the ongoing uncertainty about low-level effects and the difficulties involved in measuring arsenic concentrations below 10 µg/L or in reducing arsenic concentrations to this level, the WHO has set 10 µg/L as a provisional guideline value (WHO, 2011). Many countries have a less strict drinking-water standard of 50 µg/L. The disease burden at these levels can be considerable; Argos et al. (2010) found all-cause mortality levels to be 34% higher in a population exposed to 0.01–50 µg/L arsenic, compared to a control group with <10 µg/L exposure. Those exposed to 150 µg/L or more showed 68% higher all-cause mortality.
+Because of the ongoing uncertainty about low-level effects and the difficulties involved in measuring arsenic concentrations below 10 µg/L or in reducing arsenic concentrations to this level, the WHO has set 10 µg/L as a provisional guideline value (WHO, 2011). Many countries have a less strict drinking-water standard of 50 µg/L. The disease burden at these levels can be considerable; Argos et al. (2010) found all-cause mortality levels to be 34% higher in a population exposed to 0.01–50 µg/L arsenic, compared to a control group with <10 µg/L exposure. Those exposed to 150 µg/L or more showed 68% higher all-cause mortality.
 There is no effective medical treatment for chronic arsenicosis, except for switching to an arsenic-free drinking-water source. However, palliative care such as application of ointments to cracked skin lesions can ease suffering. Chelation therapy is effective for short-term, acute poisoning, but not for long-term exposure.