Environmental Medicine Integrating a Missing Element into Medical Education (1995) / Chapter Skim
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Case Study 1: Arsenic Toxicity
Case Study 1: Arsenic Toxicity
Pages 139-163
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From page 139... ...
Arsenic is strongly associated with lung and skin cancer in humans, and may cause other cancers as well. Arsenic Toxicity This monograph is one in a series of self-instructional publications designed to increase the primary care provider's knowledge of hazardous substances in the environment and to aid in the evaluation of potentially exposed patients.
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From page 140... ...
On initial laboratory evaluation, the CBC shows slight macrocytic anemia with hematocrit 35% (normal range 40% to 52%) , and MCV 111 fL (normal range 80 to 100 fL)
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From page 141... ...
Other potential sources of arsenic exposure are the following: Natural Sources Arsenic-containing mineral ores Groundwater (especially near geothermal activity) Commerclal Products Industrial Processes Purifying industrial gases (removal of sulfur)
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From page 142... ...
More often, however, arsine forms unexpectedly when acid or other reducing substances are added to arsenic-containing compounds, such as metals in which arsenic is a low-level contaminant. In the general population, the main route of arsenic exposure is via ingestion of arsenic-containing food and water.
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From page 143... ...
Drinking water is obtained from an artesian well located on his property. What are the potential sources of arsenic exposure for the patient described in the case study?
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From page 144... ...
Green wood or pressed wood treated with copper arsenate to prevent mildew is commonly used in marine applications, patio decks, and recreational structures for children's playgrounds. Cutting this wood or erosion of the veneer may lead to arsenic exposure.
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From page 145... ...
Arsenic is excreted primarily through the kidneys. After lowlevel exposure to inorganic arsenic, most of the urinary arsenic is present as methylated metabolites.
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From page 146... ...
O Arsenic Is strongly assoclated with lung and skin cancers and may cause other cancers. O Gastrolntestinal effects are seen primarily after arsenic Ingestion, and less often after Inhalation or dermal absorptlon.
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From page 147... ...
Case reports have also linked chronic high-level arsenic exposure with hepatic angiosarcoma, a rare form of cancer. The systemic toxicity occurring in severe acute arsenic poisoning may be accompanied by acute renal tubular necrosis.
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From page 148... ...
Follow-up studies of Japanese children who chronically consumed arsenic-contaminated milk revealed an increased incidence of severe hearing loss, mental retardation, epilepsy, and other brain damage. Hearing loss as a sequelae of acute or chronic arsenic intoxication has not been confirmed by other case reports or epidemiologic studies.
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From page 149... ...
Paradoxically, cancer associated with arsenic exposure has not been produced in experimental animals. Skin Cancer An increased risk of skin cancer in humans is associated with chronic exposure to inorganic arsenic in medication, contaminated water, and the workplace.
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From page 150... ...
Epidemiologic studies indicate that a dose-response relationship exists between the level of arsenic in drinking water and the prevalence of skin cancers in the exposed population. Excessive mortality rates due to arsenic-induced skin cancer have also been observed in vineyard workers with dermal and inhalation exposure.
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From page 151... ...
The minimal lethal dose is in the range of 50 to 300 milligrams. The signs and symptoms of acute arsenic poisoning include the following: Gastrointestinal Cardiovascular and Respiratory severe abdominal pain hypotension, shock nausea and vomiting ventricular arrhythmia bloody or rice-water diarrhea pulmonary edema Neurologic light-headedness headache weakness, lethargy delirium encephalopathy convulsions coma sensorimotor peripheral neuropathy Other rhabdomyalysis garlic odor on the breath delayed appearance of Mees lines Hepatic and Renal elevated liver enzymes hematuria, oliguria, proteinuria, acute tubular necrosis, renal cortical necrosis Hematologic anemia leukopenia thrombocytopenia disseminated intravascular coagulation 12 151 ENVIRONMENTAL MEDICINE
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From page 152... ...
A delayed sensorimotor peripheral neuropathy may occur after acute arsenic poisoning. Symptoms are initially sensory and may begin 2 to 4 weeks after resolution of the first signs of intoxication resulting from ingestion (shock or gastroenteritis)
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From page 153... ...
O Anemia often accompanies skin herons In patlonts chronically poisoned by arsenic. O Lung cancer and skin cancer are parlous long-term concerne In cases of chronic arsenic exposure.
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From page 154... ...
Fish arsenic can significantly increase total urinary arsenic levels; therefore, it may be prudent to take a dietary history of the previous 48 hours or repeat the urinary arsenic test in 2 or 3 days. Human volunteers with an average pretest urinary O Early cilnical dlagnoale of arsenic toxicity 1e often dlfflcult; a key laboratory tost In recent exposures le.urlnary arsenic oxcretlon.
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From page 155... ...
Although basophilic stippling on the peripheral smear does not confirm arsenic poisoning, it is consistent with the diagnosis. Liver transaminases are frequently elevated in acute and chronic arsenic exposure and can help confirm clinical suspicion.
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From page 156... ...
Therefore, even if arsenic ingestion is only suspected, it may be valuable to give one ortwo doses of dimercaprol while awaiting confirmation since side effects usually are not noxious enough to outweigh benefits. Another potential chelating agent is dimercaptosuccinic acid (DMSA)
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From page 157... ...
If the source of arsenic exposure has not been determined, it may be inadvisable to discharge patients until the health department or other appropriate officials have inspected their environment. Unless such inspection locates and eliminates the source of exposure, the patient may be at risk for further arsenic intoxication.
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From page 158... ...
Focus Level Commend O There 1~11ttle agreement between governmental regulatlone and the recommendatlons of advisory organizatlons on the acceptable levels of arsenic In the workplace. ACGIH Air-Workplace 200 ~g/m3 NIOSH Air-Workplace 2 ~g/m3 OSHA Air-Workplace 10 ~/m3 EPA Air-Environment N/A Water 50 ppb FDA Food 0.5-2 ppm Advisory; 8-hour TWA Advisory; 15-min ceiling limit Regulabon; PEL§over 8-hour workday Under review Regulabon; maximum contaminant level in drinking water Regulabon; applies to animals treated with veterinary drugs ACGIH ~ American Conference of Govemmental Industrial Hygienists; EPA ~ Environmental Protection Agency; FDA .
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From page 159... ...
In 1986, EPA promulgated the National Emissions Standards for Hazardous Air Pollutants for three stationary source categories known to emit organic arsenic: primary copper smelters, glass manufacturing plants, and arsenic plants. However, there is currently no ambient air standard for arsenic.
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From page 160... ...
Albers JW, Rogers L, Salanga V, Greenberg HS. Acute arsenic intoxication presenting as Guillain-Barre-like syndrome.
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From page 161... ...
Special report on ingested inorganic arsenic: skin cancer; nutritional essentiality. Washington, DC: US Environmental Protection Agency, Risk Assessment Forum, 1988.
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From page 162... ...
However, given the patient's clinical presentation, exposure to toxic inorganic arsenic is likely. In this case, speciation reveals inorganic arsenic present at 1700 ~g/L, monomethyl arsenic acid at 2200 ~g/L, and dimethyl arsenic acid at 2100 ~g/L, confirming that the patient has sustained inorganic arsenic exposure.
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From page 163... ...
Hyperpigmentation typically precedes hyperkeratoses, which in turn precede dermal neoplasms. The presence of both hyperpigmentation and palmar-plantar keratoses in the patient suggests that his arsenic exposure began at least 3 years ago, before consumption of drinking water from his current well.
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