[4] If arsenic poisoning occurs over a brief period of time, symptoms may include vomiting, abdominal pain, encephalopathy, and watery diarrhea that contains blood.

[7] Ingesting large amounts of arsenic can cause symptoms similar to food poisoning, with abdominal pain, nausea, vomiting, and diarrhea starting within hours.

Symptoms include gastrointestinal distress, headache, weakness, difficulty breathing, kidney and liver dysfunction, and the destruction of red blood cells.

[8][11] Repeated arsenic exposure also increases the risk for developing several cancers, particularly of the skin, lung, liver, bladder, prostate, and blood vessels.

[8][11] The most common arsenic-induced skin cancer is squamous cell carcinoma in situ which typically occurs 2 to 20 years after arsenic exposure.

Based on these data, the European Commission (2000) estimated that in relation to food, cigarette smoking, water, and soil, air contributes less than 1% of total arsenic exposure.

[39] Low potassium levels in the cells increases the risk of experiencing a life-threatening heart rhythm problem from arsenic trioxide.

Inorganic arsenic trioxide found in ground water particularly affects voltage-gated potassium channels,[40] disrupting cellular electrolytic function resulting in neurological disturbances, cardiovascular episodes such as prolonged QT interval, neutropenia, high blood pressure,[41] central nervous system dysfunction, anemia, and death.

[49] Dimethylarsinic acid, DMA(V), caused DNA single strand breaks resulting from inhibition of repair enzymes at levels of 5 to 100 mM in human epithelial type II cells.

In a rat animal model, urine levels of 8-hydroxy-2'-deoxyguanosine (as a biomarker of DNA damage byreactive oxygen species) were measured after treatment with DMA(V).

[63] An experiment by Zhong et al. (2001) with arsenite-exposed human lung A549, kidney UOK123, UOK109 and UOK121 cells isolated eight different DNA fragments by methylation-sensitive arbitrarily primed polymerase chain reactions.

[62][75][76] Arsenic, especially +3 As, binds to single, but with higher affinity to vicinal sulfhydryl groups, thus reacts with a variety of proteins and inhibits their activity.

[79] The remaining unbound arsenic (≤ 10%) accumulates in cells, which over time may lead to skin, bladder, kidney, liver, lung, and prostate cancers.

[71] Other forms of arsenic toxicity in humans have been observed in blood, bone marrow, cardiac, central nervous system, gastrointestinal, gonadal, kidney, liver, pancreatic, and skin tissues.

[81][84] Germolec et al. (1996) found an increased cytokine expression and cell proliferation in skin biopsies from individuals chronically exposed to arsenic-contaminated drinking water.

[87] As the contradicting findings and connected mechanistic hypotheses indicate, there is a difference in acute and chronic effects of arsenic on signal transduction which is not clearly understood yet.

[citation needed] Studies have demonstrated that the oxidative stress generated by arsenic may disrupt the signal transduction pathways of the nuclear transcriptional factors PPARs, AP-1, and NF-κB,[71][87][88] as well as the pro-inflammatory cytokines IL-8 and TNF-α.

[71][89][94][96][97] Epidemiological studies have suggested a correlation between chronic consumption of drinking water contaminated with arsenic and the incidence of type 2 diabetes.

[71] Arsenic may be measured in blood or urine to monitor excessive environmental or occupational exposure, confirm a diagnosis of poisoning in hospitalized victims or to assist in the forensic investigation in a case of fatal over dosage.

The current biological exposure index for U.S. workers of 35 μg/L total urinary arsenic may easily be exceeded by a healthy person eating a seafood meal.

The highly focused and intense beams study small spots on biological samples allowing analysis to micro level along with the chemical speciation.

[citation needed] During the Victorian era (late 19th century) in the United States, U.S. newspapers advertised "arsenic complexion wafers" that promised to remove facial blemishes such as moles and pimples.

[108]: 21  It was also a common murder technique in the 19th century in domestic violence situations, such as the case of Rebecca Copin, who attempted to poison her husband by "putting arsenic in his coffee".

Forensic studies have determined that the Guangxu Emperor (d. 1908) was murdered by arsenic, most likely ordered by the Empress Dowager Cixi or Generalissimo Yuan Shikai.

Likewise, in ancient Korea, and particularly in the Joseon Dynasty, arsenic-sulfur compounds had been used as a major ingredient of sayak (사약; 賜藥), which was a poison cocktail used in capital punishment of high-profile political figures and members of the royal family.

[110] Due to social and political prominence of the condemned, many of these events were well-documented, often in the Annals of Joseon Dynasty; they are sometimes portrayed in historical television miniseries because of their dramatic nature.

MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies.

[115] In some other countries, when developing national drinking water standards based on the guideline values, it is necessary to take account of a variety of geographical, socio-economic, dietary and other conditions affecting potential exposure.

The Environmental Protection Agency, for example, has estimated the total national annualized cost of treatment, monitoring, reporting, record keeping, and administration to enforce the MCL rule to be approximately $181 million.

[120] Studies have shown that ingesting arsenic through groundwater during pregnancy poses dangers to the pregnant woman including, but not limited to abdominal pain, vomiting, diarrhea, skin pigmentation changes, and cancer.