Arsenic is the 33rd element in the periodic table. It is a semi-metal with both metal and non-metal properties. The abundance of arsenic in the Earth's crust is 0.00021% or 1.8 milligrams of arsinic for each kilogram of dirt (1.8 mg/kg). Arsenic is readily soluble in water. Ground water is able to disolve some arsenic from the soil. In addition some plants, such as rice and some fruit trees, have a high afinity for arsenic and are able to concentrate arsenic in plant tissues. Arsenic has many industrial uses including the active ingredient in some kinds of pesticides and wood perservatives, the manufacturing of electronic components and batteries, and as a metal smelting waste product.

As a result people have several routes of exposure to arsenic: accidental soil ingestion, ingestion of water with arsenic contamination, and ingestion of plants that have bioaccumulated arsenic, or chemical exposure to aresnic as a hazardous waste or in the workplace. Everyone is exposed to some arsenic, but usually at levels low enought that the body can repair the damage.

Arsenic by itself is called elemental arsenic. In nature, arsenic is usually attached to other atoms to make an arsenic containing compound. There are two kinds of arsenic containing compounds. Organic arsenic are compounds that contain carbon. Inorganic arsenic are compounds that do not contain carbon. This is important because we know inorganic arsenic is more toxic than organic arsenic. Total arsenic is a measurement of quantity of both inorganic and organic arsenic together. After measureing the amount of total arsenic in a sample of material, the arsenic is often speciated to determine how much of the total is inorganic arsenic.

Common exposure thresholds

Drinking water maximum contaminante level (MCL) is 10 parts per billion (ppb) which is the same as 0.01 parts per million (ppm) or 0.01 milligrams arsenic per liter of water (0.01 mg/L).

Arsenic in the urine is normally less than 100 micrograms of total arsenic per liter of urine (<100 μ/L).

The 4CSBC uses the National Health and Nutrition Examination Survey (NHANES) 95th percentile level as a screening threshold. Only five percent of the NHANES participants (representing the American population) have levels that exceed the 95th percentile level. Everyone else is below that level. Thus, that level is considered elevated. It may or may not be harmful. The 95th percentile screening threshold for arsenic is 53 μg/L

Health concerns

How is arsenic toxic: Arsenic interfers with a cells ability to convert sugar into energy at several different points along the process. Arsenic may also cause cells to produce excess hyrogen peroxide resulting oxidative stress. Acute expsoure to high levels (poisoning) can lead to cell death, multiple-system organ failure, and death.

Adverse Health Effects: Arsenic effects every organ or organ system in the body. The following are some of the better known adverse health effects. During pregnancy arsenic is able to cross the placental barrier into the fetus


Sources of additional information

Agency for Toxic Substances and Disease Registry (ATSDR)

Centers for Disease Control and Prevention (CDC)

U.S. Environmental Protection Agency (EPA)

Food and Drug Administration (FDA)


Last Update: May 1, 2017