Boric Acid 329
categories together in order to achieve sufficient See also: Benzene; Carbon Monoxide; Cardiovascular
statistical power for epidemiological analysis. Never- System; Distribution; Hydrogen Sulfide; Immune System;
theless, there does appear to be sufficient evidence to Kidney; Liver.
link ANLL with certain exposures to benzene.
The association between benzene exposure and le- Further Reading
ukemia has been made since the late nineteenth cen-
tury; however, the doseresponse relationship and Braunwald E, Fauci AS, Kasper DL, et al (eds.) (2001)
mechanistic explanation have been quite conten- Harrisons Principles of Internal Medicine 15th edn.
New York: McGraw-Hill.
tious. The most reliable evidence associating chronic
Brooks SM, Gochfeld M, Herzstein J, et al. (1995)
benzene exposure with AML was presented in a ret- Environmental Medicine. St. Louis, MO: Mosby.
rospective NIOSH study of rubber hydrochloride Gribaldo L (2002) Haematotoxicology: Scientific basis and
workers in Akron, OH, from 1940 to 1949. Unfor- regulatory aspects. Alternatives to Laboratory Animals
tunately, the mechanism of how benzene exposure 30(2): 111113.
leads to the development of AML is not known. The Parent-Massin D (2001) Relevance of clonogenic assays in
two most frequently discussed potential mechanisms hematotoxicology. Cell Biology and Toxicology 17(2):
8794.
of toxicity involve either a point mutation or a chro-
Sullivan JB Jr. and Krieger GR (eds.) (1992) Hazardous
mosomal deletion. The latter is considered more Materials Toxicology: Clinical Principles of Environ-
likely since neither benzene nor its metabolites are mental Health. Baltimore, MD: Williams & Wilkins.
mutagenic or teratogenic. (2nd edn., 1998).
Blue-Green Algae See Algae.
Boric Acid
Michael Wahl application as an insecticide for crawling insects such
& 2005 Elsevier Inc. All rights reserved. as roaches. In medicine, it has been used as a disin-
This article is a revision of previous print edition article by fectant and is a constituent of baby powders, anti-
Arvind K Agarwal, volume 1, pp. 182183, & 1998, Elsevier septics, diaper rash ointments, eye washes, gargles,
Inc. and a variety of other consumer products for its mild
antiseptic property.
* CHEMICAL ABSTRACTS SERVICE REGISTRY NUMBER:
CAS 10043-35-3 Background Information
* SYNONYMS: Boracic acid; Orthoboric acid; Boro-
fax; Three elephant; NCI-C36417 Boric acid exists in natural deposits as a mineral,
* CHEMICAL FORMULA: H3BO3 sassolite. It is also found in hot mineral water sourc-
es. The minerals are extracted with sulfuric acid and
crystalline boric acid is separated.
Uses
Boric acid is used as a fireproofing agent for wood, as Exposure Routes and Pathways
a preservative, and as an antiseptic. It is used in the
Accidental ingestion and subcutaneous routes are the
manufacture of glass, pottery, enamels, glazes, cos-
primary exposure pathways. The maximum work-
metics, cements, porcelain, leather, carpets, hats,
place concentration is 10 mg m 3. The maximum
soaps, artificial gems, and in tanning, printing, dye-
concentration in water used in fisheries is 0.1 mg l 1.
ing, painting, and photography. It is a constituent of
nickling baths and electric condensers, and it is used
for impregnating wicks and hardening steel. In lab-
Toxicokinetics
oratory procedures, boric acid is used in the prepa-
ration of buffer solutions. Water emulsifying and hydrophobic ointments con-
Boric acid is also used as a fungicide and as an taining boric acid liberate only small amounts within
insecticide powder. Domestic use may include its 24 h compared with a near total liberation from a
330 Boric Acid
jelly. Boric acid is readily absorbed from the gastro- Changes on the skin include an erythematous skin
intestinal tract, mucous membranes, and abraded eruption, with papules or vesicles appearing between
skin. Boric acid is excreted unchanged in urine with the fingers and on the back of the hands initially and
B50% excreted in the first 12 h and the remainder eventually becoming generalized enough to give a
excreted over a period of a few days. The half-life of boiled lobster appearance. The skin lesions may
boric acid given orally is estimated to be 21 h. The undergo bullous formation, desquamation, excoria-
fatal dose of boric acid is estimated to be B20 g in an tion, and sloughing. Hypothermia often occurs.
adult and B5 or 6 g in an infant. Renal injury can occur, usually in the form of renal
tubular necrosis, and can be demonstrated by the
presence of oliguria, albuminuria, and eventually
Mechanism of Toxicity anuria. Signs of meningeal irritation, oliguria, and
The exact mechanism of toxicity is not known. Boric circulatory collapse may be followed by death within
acid can inhibit production of adenosine triphos- 5 days. Infants and young children are more suscep-
phate, a cellular form of energy. tible to boric acid intoxication. Low levels of boric
acid ingestion may lead to dry skin and mucous
membranes, followed by the appearance of a red
Acute and Short-Term Toxicity tongue, patchy alopecia, cracked lips, and con-
(or Exposure) junctivitis. Infertility among men is possible.
Animal No major toxicological distinctions between boric
acid and its salts are recognized in human beings.
Animals have demonstrated similar toxic effects to
those seen in humans.
In Vitro Toxicity Data
Human
No mutagenic effects have been seen in Salmonella
Acute boric acid poisoning is extremely rare. Symp- typhii strains TA98 and TA100 via the preincubation
toms in extremely large doses will be similar to those method.
seen in chronic overexposure (see below).
Clinical Management
Chronic Toxicity (or Exposure) There is no specific antidote. Supportive care should
Animal be instituted for all patients with history of serious
boric acid exposure. Substantial recent ingestions
Dogs and rats were able to tolerate boric acid doses may benefit from administration of activated char-
of up to 350 ppm for 2 years. Larger doses of boric coal. Fluid and electrolyte balance, correction of
acid (1750 ppm) over a period of time have been acid/base disturbance, and control of seizures are es-
shown to cause testicular damage and sterility in rats sential to therapy. Hemodialysis has been successful-
and dogs. ly used to treat acute boric acid poisoning. Sodium
bicarbonate may be used for any metabolic acidosis.
Human
Toxicity may occur after ingestion, injection, appli-
cation to damaged skin (e.g., abrasion, burns, or See also: Cosmetics and Personal Care Products; Fed-
diaper rash), lavage, or enema. Severe systemic toxi- eral Insecticide, Fungicide, and Rodenticide Act, US;
city is most likely to occur from repeated dermal app- Nickel and Nickel Compounds.
lication to damaged skin; this has been reported
mainly in the treatment of diaper rash in young chil- Further Reading
dren. Symptoms include nausea, vomiting, bloody
diarrhea, severe colic, and abdominal pain. There Litovitz TL, Klein-Schwartz W, and Oderda GM (1988)
may be restlessness, delirium, headache, tremors, Clinical manifestations of toxicity in a series of 784 boric
acid ingestions. American Journal of Emergency Medi-
and generalized convulsions usually followed by cine 6: 209213.
weakness and coma. There is fever and tachypnea Restuccio A, Mortensen ME, and Kelley M (1992) Fatal
followed by CheyneStokes-type respirations and ingestion of boric acid in an adult. American Journal of
respiratory arrest. Emergency Medicine 10: 545547.
