TOP 20 SOURCES OF HUMAN EXCESS ARSENIC EXPOSURE

#	Source	Main arsenic concern	Typical exposure route
1	Arsenic-contaminated groundwater / well water	Predominantly inorganic As(III)/As(V)	Drinking, cooking
2	Rice and rice products	Relatively high inorganic arsenic	Food
3	Occupational metal smelting	Inorganic arsenic particulates/fumes	Inhalation, ingestion
4	Mining, especially arsenic-containing ores	Inorganic arsenic in dust/water	Inhalation, ingestion
5	Contaminated soil	Inorganic arsenic	Ingestion of soil/dust
6	Arsenic-containing pesticides / historical pesticide residues	Inorganic arsenic and methylated arsenicals	Food, soil, occupational
7	CCA pressure-treated wood	Arsenic released from chromated copper arsenate	Soil/dust/contact
8	Tobacco smoke	Inorganic arsenic	Inhalation
9	Rice-based infant cereals/foods	Inorganic arsenic	Food
10	Contaminated irrigation water	Inorganic arsenic transferred to crops	Food
11	Industrial emissions / air pollution	Arsenic-containing particulates	Inhalation
12	Coal combustion	Arsenic-containing airborne particles/ash	Inhalation, ingestion
13	Burning arsenic-treated wood	Inorganic arsenic in smoke/ash	Inhalation
14	Certain occupational glass/pigment manufacturing	Arsenic compounds	Inhalation/occupational
15	Arsenic-containing industrial wastes / hazardous sites	Inorganic arsenic	Soil, dust, water
16	Certain traditional/imported remedies	Sometimes inorganic arsenic	Oral ingestion
17	Seaweed/algae	Can contain inorganic arsenic as well as organic arsenicals	Food
18	Fruit juices, particularly apple juice	Inorganic arsenic contamination	Food/drink
19	Other crops grown in arsenic-contaminated soil/water	Inorganic arsenic	Food
20	Occupational semiconductor/electronics work	Arsenic compounds, particularly specialized industrial compounds	Inhalation/occupational

1. Contaminated groundwater — particularly important

This is one of the most important sources of toxic inorganic arsenic. Naturally arsenic-rich geological formations can contaminate groundwater, and contamination can also arise from mining, industrial activity and historical agricultural chemicals. WHO identifies contaminated groundwater as the greatest public-health threat from arsenic globally.

In the United States, private wells deserve particular attention because they are not routinely monitored in the same way as regulated public water systems. ATSDR specifically recommends testing private well water for arsenic.

2. Rice

Rice is unusual among common grains because it efficiently takes up arsenic from soil and irrigation water. Flooded cultivation conditions can increase arsenic availability to rice plants. FDA considers rice and rice products a major dietary source of inorganic arsenic.

3–4. Mining and metal smelting

Mining and smelting can release arsenic into air, soil and water. Copper and lead smelting are specifically identified by ATSDR as occupational exposure settings.

5–7. Soil, historical pesticides and CCA-treated wood

Arsenic can remain in soil long after historical arsenical pesticides were applied. ATSDR notes that contaminated soil may occur around former agricultural areas, mining/smelting sites and arsenic-rich geological deposits. CCA-treated lumber was formerly widely used for residential structures and playground equipment; arsenic can migrate from the wood into surrounding soil.

8. Tobacco

Tobacco plants can accumulate arsenic from soil. Tobacco smoke therefore provides an inhalational exposure route. Historically, exposure could be higher because arsenical pesticides were used on tobacco crops.

9–10. Infant rice products and contaminated irrigation

Infant rice cereal is important because infants can receive substantial exposure relative to their body weight. FDA specifically developed an action level for inorganic arsenic in infant rice cereal.

Irrigation with arsenic-contaminated groundwater can transfer arsenic into crops and consequently into the food chain.

11–15. Industrial and combustion sources

Arsenic-containing particulate matter can arise from smelting, industrial operations, coal combustion and burning arsenic-treated wood. ATSDR identifies tobacco smoke, burning CCA-treated wood or arsenic-containing coal, and emissions from nearby smelting operations as inhalational sources.

16. Traditional/imported remedies

Some traditional, imported, homeopathic and naturopathic remedies have been found to contain inorganic arsenic. This is particularly important because the product may be intentionally consumed rather than recognized as an environmental contaminant.

17. Seaweed and seafood — important qualification

Seafood can contain very high total arsenic, but this can be misleading. Fish and shellfish predominantly contain arsenobetaine and related organic arsenicals that are much less toxic than inorganic arsenic. Seaweed can have a different arsenic profile and may contain appreciable inorganic arsenic.

18. Fruit juice

FDA has established guidance concerning inorganic arsenic in apple juice, reflecting concern about dietary exposure from contaminated food/drink.

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The most important distinction for a clinical/toxin table

If your goal is “what sources are most likely to produce biologically important excess inorganic arsenic in a human?”, I would separate the 20 sources into:

Highest-priority sources to investigate

1. Contaminated well water
2. Contaminated municipal water in affected geographic areas
3. Rice/rice products
4. Arsenic-contaminated irrigation water
5. Mining exposure
6. Metal-smelting exposure
7. Contaminated soil
8. Historical arsenical pesticides
9. CCA-treated wood/soil
10. Tobacco smoke

Important but highly dependent on circumstances
11. Coal combustion
12. Burning treated wood
13. Industrial air emissions
14. Hazardous waste sites
15. Occupational glass/pigment work
16. Semiconductor/electronics work
17. Arsenic-containing traditional remedies
18. Seaweed
19. Fruit juice
20. Other contaminated crops/animal products

This ordering is not a toxicity ranking; it separates common/highly relevant exposure pathways from sources whose importance varies greatly by occupation, geography, diet and arsenic chemical form. WHO and ATSDR both emphasize that chemical form, dose, duration and route of exposure matter greatly.

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Clinician Brief: Arsenic. May 15, 2025.
2. World Health Organization (WHO). Arsenic — Fact Sheet.
3. U.S. Food and Drug Administration (FDA). Arsenic in Food.
4. U.S. Food and Drug Administration (FDA). What You Can Do to Limit Exposure to Arsenic.
5. FDA. Supporting Document for Action Level for Inorganic Arsenic in Rice Cereals for Infants.
6. ATSDR. Toxicological Profile for Arsenic.
7. ATSDR. Toxicological Profile for Arsenic — General Population and Occupational Exposure.
8. FDA Total Diet Study. FY2018–FY2020 TDS Elements Report.
9. Arslan B, Djamgoz MBA, Akün E. Arsenic: a review on exposure pathways, accumulation, mobility and transmission into the human food chain. Reviews of Environmental Contamination and Toxicology. 2017;243:27–51.
10. Argos M, Ahsan H, Graziano JH. Arsenic and human health: epidemiologic progress and public health implications. Reviews on Environmental Health. 2012;27(4):191–195.