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DESCRIPTION
- Boron is a natural component of many foods.
- Compounds containing boron are termed borates.
- Boric acid is colorless and odorless.
FORMS AND USES
- Boric acid is available as crystals, granules, and white powder.
- Borax is sodium borate and is widely used as a cleaning agent.
- Occupational sources include the manufacturing of glass, fire resistant materials, glazes, enamels, paints, paperboard, wood preservatives, cleaning compounds, insecticides, and herbicides.
- Household sources include medicated powders, topical astringents, antiseptic lotions, and insecticide for ants and roaches.
- In the past, it was also used as a topical home remedy for diaper rash and as an oral home remedy combined with honey for mucous membrane irritation in children.
TOXIC DOSE
- Boric acid ingestion of a few grams (1 teaspoon of 100% boric acid powder or granules) may be lethal in small children.
- Much larger doses are required in adults.
PATHOPHYSIOLOGY
- Dermal exposure is the most common route, but oral exposure results in greater toxicity.
- Severe toxicity in infants typically involves repeated exposure.
- The mechanism of toxicity is unknown.
EPIDEMIOLOGY
Death has occurred in some instances when boric acid was administered to infants orally as a home remedy.
WORKPLACE STANDARDS
- Sodium tetraborate anhydrous
- ACGIH. TLV TWA is 1 mg/m3.
- OSHA. PEL TWA is 10 mg/m3.
- Sodium tetraborate decahydrate
- ACGIH. TLV TWA is 5 mg/m3.
- OSHA. PEL TWA is 10 mg/m3.
- Sodium tetraborate pentahydrate
- ACGIH. TLV TWA is 1 mg/m3.
- OSHA. PEL TWA is 10 mg/m3.
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DIFFERENTIAL DIAGNOSIS
Other causes of nausea, vomiting, and diarrhea in combination with a skin rash primarily include infectious diseases.
SIGNS AND SYMPTOMS
Vital Signs
- Signs of dehydration are common.
- Fever is rare.
HEENT
- Mucous membrane involvement is common.
- Alopecia occurs rarely.
Dermatologic
- Localized erythema often progresses to diffuse erythema and then to generalized exfoliation.
- Exfoliation can be full thickness and indistinguishable from toxic epidermal necrolysis
Gastrointestinal
- Persistent nausea, vomiting, and diarrhea are very common.
- Vomitus and diarrhea may be bluish-green in color.
- Hematemesis and hematochezia are common.
Renal
Renal insufficiency with oliguria is common and may progress to anuric renal failure.
Fluids and Electrolytes
Dehydration with associated hypernatremia, hyperchloremia, and metabolic acidosis is common.
Neurologic
- Irritability, headache, abnormal movements, personality changes, and altered mental status are common.
- Symptoms may progress to seizures and coma.
PROCEDURES AND LABORATORY TESTS
Essential Tests
No test may be needed in asymptomatic patients.
Recommended Tests
- Serum electrolytes, BUN, and creatinine are used to assess severity and to guide supportive therapy.
- The normal serum boron concentration is less than 0.8 mg/dl. Elevated levels can confirm exposure, but do not correlate well with toxicity.
- ECG, serum acetaminophen and aspirin levels are used in overdose setting to detect occult ingestion.
- Head CT, lumbar puncture, and cultures should be performed as needed to evaluate altered mental status.
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Treatment should focus on general supportive care and correction of electrolyte abnormalities.
DECONTAMINATION
Out of Hospital
- Dermal
- If solid form, the crystals, granules, or powder are removed with a dry towel and the area is then irrigated copiously with water.
- If a solution containing boric acid is involved, irrigate the area copiously with water.
- Gastrointestinal
- Ipecac should be administered to induce emesis within 1 hour of ingestion for the alert pediatric or adult patient if health-care evaluation will be delayed.
- If vomiting has already occurred for an adult or pediatric patient, no further decontamination may be necessary.
In Hospital
- Dermal
- If solid form, the crystals, granules, or powder are removed with a dry towel and the area is then irrigated copiously with water.
- If a solution containing boric acid is involved, irrigate the area copiously with water.
- Gastrointestinal
- Ipecac should be administered to induce emesis within 1 hour of ingestion for the alert patient who is too small to have effective gastric lavage. If vomiting has already occurred, no further decontamination may be necessary.
- Gastric lavage should be performed in pediatric (tube size 24-32 French) or adult (tube size 36-42 French) patients for large ingestion presenting within 1 hour of ingestion or if serious effects are present.
- Activated charcoal is not recommended because it does not bind well with boric acid.
ANTIDOTES
There is no specific antidote to boric acid poisoning.
ADJUNCTIVE TREATMENT
- Urine output should be maintained at 1 to 2 ml/kg/h using isotonic intravenous fluid.
- Case reports suggest that hemodialysis, peritoneal dialysis, or exchange transfusion can remove borates and improve outcome.
- Sterile dressings should be applied to skin wounds.
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PATIENT MONITORING
Fluid and electrolyte status, including renal function, should be monitored.
EXPECTED COURSE AND PROGNOSIS
- Following acute ingestion, toxicity may be delayed several hours; peak toxicity occurs in 1 to 2 days.
- Following chronic ingestion, recovery is slower and more likely incomplete.
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ICD-9-CM 989Toxic effect of other substances, chiefly nonmedicinal as to source.
RECOMMENDED READING
Baker MD, Bogeina SG. Ingestion of boric acid by infants. Am J Emerg Med 1986;4:358-361.
Author: Edwin K. Kuffner
Reviewer: Richard C. Dart