Hydrogen Cyanide

ATSDR • General Information 1 

### Hydrogen Cyanide ( HCN )

CAS 74

- 90 -8 ; UN 1 051

Synonyms include formonitrile. Aqueous solutions are referred to as hydrocyanic acid and prussic

acid.

**•** Persons whose clothing or skin is contaminated with cyanide

- containing solutions can secondarily contaminate response personnel by direct contact or through off -gassing

vapor.

**•** Hydrogen cyanide is a colorless or pale- blue liquid at room temperature. It is very volatile, readily producing flammable and toxic concentrations at room temperature. Hydrogen cyanide gas mixes well with air, and explosive mixtures are easily formed.

**•** Hydrogen cyanide has a distinctive bitter almond odor, but some individuals cannot detect it and consequently, it may not provide adequate warning of hazardous

concentrations.

**•** Hydrogen cyanide is absorbed w ell by inhalation and can produce death within minutes. Substantial absorption can occur through intact skin if vapor concentration is high or with direct contact with solutions, especially at high ambient temperatures and relative humidity. Exposure by an y route may cause systemic effects.



### Description At temperatures below 78 ° F, hydrogen cyanide is a colorless or pale

- blue liquid (hydrocyanic acid); at higher temperatures, it is a colorless gas. Hydrogen cyanide is very volatile, producing potentially lethal concentrations at room temperature. The vapor is flammable and potenti ally explosive. Hydrogen cyanide has a faint, bitter almond odor and a bitter, burning taste. It is soluble in water and is often used as a 96% aqueous solution (NIOSH 2005).



### Routes of Exposure

Inhalation Hydrogen cyanide is readily absorbed from the lungs; symptoms of poisoning begin within seconds to minutes. The odor of hydrogen cyanide is detectable at 2 –10 ppm (OSHA PEL = 10 ppm), but does not provide adequate warning of hazardous concentrations . Perception of the odor is a genetic trait (20

– 40% of the general population cannot detect hydrogen cyanide); also, rapid olfactory fatigue can occur. Hydrogen cyanide is lighter than air (HSDB 2007 ).Hydrogen Cyanide

2 General Information • ATSDR Children exposed to the same levels of hydrogen cyanide as adults may receive larger doses because they have greater lung surface area:body weight ratios and increased minute volumes:weight ratios.

Skin/Eye Contact Exposure to hydrogen cyanide can cause skin and eye irritation. More importantly, skin or eye absorption is rapid and contributes to systemic poisoning. After skin exposure, onset of symptoms may be immediate or delayed for 30

– 60 minutes. Most cases of toxicity from dermal exposure

ha ve been from industrial accidents involving partial immersion in liquid cyanide or cyanide solutions or from contact with molten cyanide salts, resulting in large surface

area burns (ATSDR 2006).

Children are more vulnerable to toxicants absorbed throu gh the skin because of their relatively larger surface area:body weight ratio.

Ingestion Ingestion of hydrogen cyanide solutions or cyanide salts can be rapi dly fatal (ATSDR 2006)

. Treatment of ingested cyanid e salts is similar to treatment of oral hydrogen cyanide poisoning because cyanide salts form hydrogen cyanide in acidic conditions.



### Sources/Uses Hydrogen cyanide is manufactured by oxidation of

ammonia

- metha ne mixtures under controlled conditions and by the catalytic decomposition of formamide. It may be generated by treating cyanide salts with acid, and it is a combustion by

- product of nitrogen

- containing materials such as wool, silk, and plastics. It is also produced by enzymatic hydrolysis of nitriles and related chemicals. Hydrogen cyanide gas is a b y

- product of coke

- oven and

blast -furnace operations (ATSDR 2006; Hartung 1994).

Hydrogen cyanide is used in fumigating; electroplating; mining; and in producing synthetic fibers, plastics, dyes, and pesticides. It also is used as an intermediate in chemical syntheses (Hartung 1994). Hydrogen cyanide may also be found in cigarette smoke (ATSDR 2006; HSDB 2007 ).



### Standards and Guidelines OSHA PEL (permissible exposure limit) (ceiling) = 10 ppm (skin) (averaged over 15 minutes) (OSHA 1999)Hydrogen Cyanide

ATSDR • General Information 3 EPA AEGL

- 1 (Acute Exposure Guideline Level

- 1) = 2.5 ppm (10- minute) to 1 ppm (8-hour) (EPA 2007).



### Phy sical Properties Description: Colorless gas or colorless or pale-blue liquid

Warning properties : Almond odor; inadequate warning

because rapid olfactory fatigue can occur and 20–40% of the general population cannot smell hydrogen cyanide.

Molecular weight: 27.03 daltons

Boiling point (760 mm Hg): 78 **Ε** F (25.6 ° C)

Freezing point : 8 **Ε** F ( -13.4 ° C)

Specific gravity: 0.69 (water = 1)

Vapor pressure: 630 mm Hg at 68 ° F (20 ° C)

Gas density: 0.94 (air = 1)

Water solubility : Miscible with water

Flammability: Flammable at temperatures > 0 ° F ( -18 ° C)

Flammable range : 5.6–40% (concentration in air) (ATSDR 2006)



### Incompatibilities Hydrogen cyanide reacts with amines, oxidizers, acids, sodium hydroxide, calcium hydroxide, sodium carbonate,

caustic sub stances, and ammonia. Hydrogen cyanide may polymerize at 122–140 °F (NIOSH 2005).Hydrogen Cyanide

4 Health Effects • ATSDR 

### Health Effects

**•** Hydrogen cyanide is highly toxic by all routes of exposure and may cause abrupt onset of profound CNS, cardiovascular, and respiratory effects, leading to death

within minutes.

**•** Exposure to lower concentrations of hydrogen cyanide may produce eye irritation, headache, confusion, nausea, and vomiting followed in some cases by coma and

death.

**•** Hydrogen cyanide acts as a cellular asphyxiant. By binding to mitochondrial cytochrome oxidase, it prevents the utilization of oxygen in cellular metabolism. The CNS and myocardium are particularly sensitive to the toxic effects of cyanide.



### Acute Exposure In humans, cyanide combines with the ferric ion in

mitocho ndrial cyto chrome oxidase, preventing electron transport in the cytochrome system and bringing oxidative phosphorylation and ATP production to a halt. The inhibition of oxidative metabolism puts increased demands on anaerobic glycolysis, which

results in lactic acid production and may produce

severe acid

- base imbalance. The CNS is particularly sensitive to the toxic effects of cyanide, and exposure to hydrogen cyanide generally produces symptoms within a short period of time (ATSDR 2006).

Children do not always respond to chemicals in the

same manner as adults. Different protocols for managing their care may be needed.

CNS CNS signs and symptoms usually develop rapidly. Initial symptoms are nonspecific and include excitement, dizziness, nau sea, vomiting, headache, and weakness. As poisoning progresses, drowsiness, tetanic spasm, lockjaw, convulsions, hallucinations, loss of consciousness, and coma may occur (ATSDR 2006).

Cardiovascular Abnormal heartbeat can occur in cases of severe poisoning. Slow heartbeat, intractable low blood pressure, and death may result. High blood pressure and a r apid heartbeat may be early, transient findings (ATSDR 2006).Hydrogen Cyanide

ATSDR • Health Effects 5 Respiratory After systemic poisoning begins , victims may complain of shortness of breath and chest tightness. Pulmonary findings may include rapid breathing and increased depth of respirations. As poisoning progresses, respirations become slow and gasping; a bluish skin color may or may not be pres ent. Accumulation of fluid in the lungs may develop (ATSDR 2006).

Children may be more vulnerable to gas exposure because of relatively increased minute ventilation per kg and failure to recognize the need to promptly evacuate an area when exposed.



### Metabolic An anion

- gap, metabolic acidosis occurs in severe poisoning from increased blood levels of lactic acid (ATSDR 2006).

Because of their higher metabolic rates, children may

be more vulnerable to toxic ants interfering with basic

metabolism.



### Dermal Dermal contact with hydrogen cyanide can cause skin irritation (HSDB 200 7 ).

Dermal absorption can occur, leading to systemic toxicity. Absorption occurs more readily at high

ambien t temperature and relative humidity (ATSDR 2006).

Because of their relatively larger surface area:body weight ratio, children are more vulnerable to toxicants absorbed through the skin.

Ocular/Ophthalmic W hen splashed in the eye, hydrogen cyanide can cause eye irritation and swelling. Eye contact with cyanide salts has produced systemic symptoms in experimental animals (ATSDR 2006). Dilated pupils are common in severe poisoning. Transient blindness can occur, although it rarely does (HSDB, 2014).

Pot ential Sequelae Survivors of severe exposure may suffer brain damage Cases of neurologic sequelae such as personality changes, memory deficits, disturbances in voluntary muscle movements, and the appearance of involuntary movements (i.e., extrapyramidal syndromes) have been

report ed (ATSDR 2006).Hydrogen Cyanide

6 Health Effects • ATSDR 

### Chronic Exposure Chronically exposed workers may complain of headache, eye irritation, easy fatigue, chest discomfort, palpitations, loss of appetite, and nosebleeds (ATSDR 2006).

Chronic exposure may be more serious for children because of their potential longer life span.

Carcinogenicity Hydrogen cyanide has not been classified for carcinogenic effects (IARC 2007 ; IRIS 2007 ; NTP 2005), and no carcinogenic effects have been reported for hydrogen cyanide.

Reproductive and Developmental Effects No hydrogen cyanide -induced developmental effects have been reported in humans or in animals at exposure l evels that were not maternally toxic (ATSDR 2006). Mild reproductive effects of sodium cyanide have been reported in rats and mice administered the substance orally for 13 weeks (ATSDR 2006). Increased levels of thiocyanate in the

umbilical cords of fetuses whose mothers smoked compared to those whose mothers were non -smokers suggests that thiocyanate, and possibly also cyanide, can cross the placenta. No data were located pertaining to hydrogen cyanide in breast milk (ATSDR 2006).Hydrogen Cyanide

ATSDR • Prehospital Management 7 

### Prehospital Management

**•** A v ictim exposed to hydrogen cyanide gas could secondar ily contaminate a

rescuer attempting resuscitation without a respiratory barrier. Victims whose clothing or skin is contaminated with hydrogen cyanide liquid or solution can secondarily contaminate response personnel by direct contact or through off

gassing vapor. Avoid dermal contact with cyanide- contaminated victims or with gastric contents of victims who may have ingested cyanide-containing materials.

**•** Hydrogen cyanide poisoning is marked by abrupt onset of profound toxic effects that may include syncope, seizures, coma, gasping respirations, and cardiovascular collapse, causing death within minutes. These effects can occur from all routes of exposure.

**•** Vict ims exposed to hydrogen cyanide r equire supportive care and rapid administration of specific antidotes.



### Hot Zone Rescuers should be trained and appropriately attired

befor e entering the Hot Zone. If the proper equipment is not available, or if rescuers have not been trained in its use, assistance should be obtained from a local or regional HAZMAT team or other properly equipped response organization.

Rescuer Protection Hydrogen cyanide is a highly toxic systemic poison that is absorbed well by inhalation and through the

skin.

Respiratory Protection : Positive

- pressure, self

contained breathing apparatus (SCBA) is recommended in response situations that involve exposure to potentially unsafe levels of hydrogen cyanide (HSDB 2007 ).

Skin Protection : Chemical

- protective clothing against hydrogen cyanide is recommended because both hydrogen cyanide vapor and liquid can be absorbed through the skin to produce systemic toxicity.

ABC Reminders Quickly establish a patent airway, ensure adequ ate respiration and pulse. If trauma is suspected, maintain cervical immobilization manually and apply a cervical

collar and a backboard when feasible.Hydrogen Cyanide

8 Prehospital Management • ATSDR Victim Removal If victims can walk, lead them out of the Hot Zone to

the Decont amination Zone. Victims who are unable to walk may be removed on backboards or gurneys; if these are not available, carefully carry or drag victims to safety.

V ictims with chemically

- induced acute disorders may suffer from anxiety , especially children who may be separated from a parent or other adult.



### Decontamination Zone Patients exposed only to hydrogen cyanide gas who

have no e ye irritation do not need decontamination. They may be transferred immediately to the Support

Zone. Other patients will require decontamination as

described below.

Rescuer Protection If exposure levels are determined to be safe, decontamination may be conducted by personnel wearing a lower level of protection than that worn in

th e Hot Zone (described above). However, do not attempt resuscitation without a respiratory barrier.

ABC Reminders Quickly establish a patent airway, ensure adequate respiration and pulse. Stabilize the cervical spine with

a collar a nd a backboard if trauma is suspected. Administer supplemental oxygen as required. Assist ventilation with a bag -valve- mask device if necessary.

Basic Decontamination Speed is critical. For symptomatic victims, provide

treatment wi th 100% oxygen and specific antidotes as needed. Treatment should be given simultaneously with decontamination procedures. (For treatment, see
ABC Reminders, Advanced Treatment, and Antidotes below).

Victims who are able may assist with their own decontamination. Quickly remove and double -bag contaminated clothing and personal belongings.

Flush exposed skin and hair with copious amounts of

water for at least 20 minutes. Wash with soap and rinse thoroughly with water. Use caution to avoid hypothermia when decontaminating victims, particularly children or the elderly. Use blankets or

warmers as needed.Hydrogen Cyanide

ATSDR • Prehospital Management 9 Flush exposed or irritated eyes with plain water or

saline for 5 minutes. Remove contact lenses if easily removable without additional trauma to the eye. Continue eye irrigation during other basic care or transport (HSDB 2007 ). If pain or injury is evident, continue irrigation while transferring to the Support

Zone.

In cases of ingestion, do not induce emesis

. If the victim is symptomatic, immediately institute emergency life support measures including the use of a cyanide antidote ( see Antidotes below).

Provide reassurance to chemically

- contaminated

victim s during decontamination, particularly children who may suffer separation anxiety if separation from a

parent occurs.

Transfer to Support Zone As soon as basic decontamination is complete, move

the victim to t he Support Zone.



### Support Zone Be certain that victims have been decontaminated properly (see Decontamination Zone above). Victims who have undergone decontamination pose no serious risks of secondary contamination to rescuers. In s uch cases, Support Zone personnel require no s pecialized protective gear.

ABC Reminders Quickly establish a p atent airway, ensure adequate respiration and pulse. If trauma is suspected, maintain cervical immobilization manually and apply a cervical

collar and a backboard when feasible. Administer supplemental oxygen as required and establish intravenous access if necessary. Place on a cardiac

monitor.

Patients who rapidly regain consciousness and who have no ot her signs or symptoms may not require

antidotal treatment. Those who remain comatose or develop shock should be treated promptly with the antidotes in the cyanide antidote kit (see Antidotes below).

Additional Decontamination Continue irrigating exp osed skin and eyes, as appropriate.Hydrogen Cyanide

10 Prehospital Management • ATSDR In cases of ingestion, do not induce emesis

. If the patient is symptomatic, immediately institute emergency life support measures, including the use of a cyanide antidote ( see Antidotes below).

Advanced Treatment In cases of respiratory compromise

, secure airway and support respiration according to advanced life support (ALS) protocols.

Patients who are in shock or have seizures should be treated according to ALS protocols. These patients or those who have arrhythmias may be seriously acidotic; consider giving, under medical supervision, 1 mEq/kg intravenous sodium bicarbonate (HSDB 2007 ).

Antidotes When possible, treatment with cyanide antidotes should be given under medical supervision to unconscious victims who have known or strongly suspected cyanide poisoning. There are currently two cyanide antidotal kits approved by the U.S. Food and Drug Administration (FDA). Use either the standard cyanide antidotal kit tha t includes amyl nitrite perles

and intravenous infusions of sodium nitrite and sodium

thiosulfate or the recently approved cyanokit that employs intravenous infusion of hydroxocobalamin (FDA 2006; HSDB 2007 ).

Use of the standard cyanide antidotal kit includes the following: Amyl nitrite perles should be broken onto a gauze pad and held under the nose, over the Ambu

valve intake, or placed under the lip of the face mask. Inhale for 30 seconds every minute and use a new perle every 3 minutes if sodium nitrite infusions will be delayed (HSDB 2007 ). If the patient has not responded to oxygen and amyl nitrite treatment, infuse sodium nitrite intravenously as soon as possible. The usual

adult dose is 10 mL of a 3% solution (300 mg) infused

over absolutely no l ess than 5 minutes ; the average pediatric dose is 0.12 –0.33 mL/kg body weight up to

10 mL infused as above. Monitor blood pressure during sodium nitrite administration, and slow the rate of infusion if hypotension develops (HSDB 2007 ). Next, infuse sodium thiosulfate intravenously. The

usual adult dose is 50 mL of a 25% solution (12.5 g)

infused over 10 –20 minutes; the average pediatric dose

is 1.65 mL/kg of a 25% solution. Repeat one

- half ofHydrogen Cyanide

ATSDR • Prehospital Management 11 the initial dose 30 minutes later if there is an inadequate clini cal response (HSDB 2007 ).

Use of the Cyano kit includes the following: I nfuse hyd roxocobalamin (5 g) intravenously over

15 minutes. Depending on the severity of poisoning and the clinical response, a second dose of 5 g may be

administered over 15 minute s to 2 hours (based on patient condition). The recommended diluent is 0.9% sodium chloride. Some drugs are incompatible with hydroxocobalamin, in which case

, a separate intravenous line may be necessary (Drugs.com 2007).

Transport to Medical Facility Only decontaminated patients or patients not requiring decontamination should be transported to a medical facility. “Body bags” are not recommended.

Report to the base station and the receiving medical facility the condition of the p atient, treatment given, and estimated time of arrival at the medical facility.

If a cyanide

- containing solution has been ingested, prepare the ambulance in case the victim vomits. Have ready several towels and open plastic bags to quickly clean up and isolate vomitus.



### Multi-Casualty Triage Consult with the base station physician or the regional poison control center for advice regarding triage of multiple victims.

Patients with evidence of significant hydrogen cyanide

expo sure, and all patients with oral exposure to hydrogen cyanide and t hose with potentially hazardous dermal exposure

, should be transported to a medical facility for evaluation.

Patients who have only brief inhalation exposure and mild or transient sym ptoms may be discharged from the scene after their names, addresses, and telephone numbers are recorded. They should be advised to seek medical care promptly if symptoms develop or recur (see Patient Information Sheet below).Hydrogen Cyanide

12 Emergency Department Management • ATSDR 

### Emer gency Department Management

**•** Hospital personnel in an enclosed area can be secondarily contaminated by vapor off-gassing from heavily soaked clothing or skin, or from vomitus. Avoid dermal contact with cyanide- con taminated patients or with gastric contents of patients who may have ingested cyanide-containing materials. Patients do not pose secondary contamination risks after contaminated clothing is removed and

the skin is washed.

**•** H ydrogen cyanide poisoning is mar ked by abrupt onset of profound health effects that may include syncope, seizures, coma, gasping respirations, and cardiovascular collapse, causing death within minutes.

**•** Patients exposed to hydrogen cyanide can survive with supportive care and rapid administration of specific antidotes.



### Decontamination Area Previously decontaminated patients and patients exposed only to hydrogen cyanide gas and have no skin or eye irritation may be transferred immediately to

the Critical Care Area. Oth er patients require

decontamination as described below.

ED personnel should don butyl rubber gloves and aprons before treating patients who have been exposed to hydrogen cyanide liquid or solutions. Hydrogen cyanide readily penetrates most rubbers and barrier fabrics or creams, but butyl rubber provides good skin protection for a short period of time.

Be aware that use of protective equipment by the provider may cause anxiety, particularly in children, resulting in decreased compliance with further management efforts.

Because of their relatively larger surface area:body weight ratio, children are more vulnerable to toxicants absorbed through the skin.

ABC Reminders Evaluate and support airway, breathing, and circulation according to ALS protocols.

Patients who are comatose, hypotensive, or have seizures or cardiac dysrhythmias should be treated in the conventional manner. If not previouslyHydrogen Cyanide

administered, give sodium bicarbonate intravenously to these patients (HSDB 2007 ). Further bicarbonate therapy should be guided by ABG measurements.

Basic Decontamination Patients who are able may assist with their own

decontamination. Remove and double -bag contaminated clothing and personal belongings.

Sp eed is critical. If the patient is symptomatic, immediately institute emergency life support measures, including the use of a cyanide antidote kit ( see Antidotes in the Prehospital Management

section above ).

If the patient’s clothing is wet with hydrog en cyanide solution, quickly remove contaminated clothing while flushing exposed skin and hair with plain water for 2

– 3 minutes (preferably under a shower), then wash twice with mild soap (HSDB 2007 ). Use caution to avoid hypothermia when decontaminating v ictims, particularly children or the elderly. Use blankets or

warmers as needed.

Irrigate exposed eyes for at least 5 minutes. Remove contact lenses if easily removable without additional trauma to the eye. Continue irrigation while transporting the pa tient to the Critical Care Area.

In cases of ingestion, do not induce emesis . If the victim is alert, asymptomatic, and has a gag reflex,

consider administering a slurry of activated charcoal at a dose of 1 g/kg (infant, child, and adult dose) (HSDB

2007 ). Because cyanide absorption from the gut is rapid, the effectiveness of activated charcoal will depend on how quickly after ingestion it can be

administered. Consider gastric lavage if the patient is conscious and it can be performed shortly after inge stion. Isolate gastric washings and vomitus; they may off

- gas hydrogen cyanide (HSDB 2007 ).



### Critical Care Area Be certain that appropriate decontamination has been carried out (see Decontamination Area above).

ATSDR • Emergency Department Management 13Hydrogen Cyanide

14 Emergency Department Management • ATSDR ABC Reminders Evaluate and support airway, breathing, and circulation

as in ABC Reminders above under Decontamination

Zone . Establish intravenous access in seriously ill patients if this has not been done previously. Continuously monitor cardiac rhythm.

Patients who are in shock or have seizures should be treated according to ALS protocols. These patients or those who have dysrhythmias may be seriously acidotic; consider giving 1 mEq/kg intravenous sodium bicarbonate (HSDB 2007 ).

Inhalation Exposure Inhalation is the primary route of exposure to hydrogen cyanide. Refer to Antidotes and Other Treatments below for appropriate clinical treatment of systemic

effects.

Skin Exposure If the skin contacted h ydrogen cyanide liquid or cyanide solutions, chemical burns may occur; treat as thermal burns. Watch for signs or symptoms of systemic toxicity, which may be delayed in onset for up to 1 hour.

Eye Exposure Continue irrigation for a t least 15 minutes. Test visual acuity. Examine the eyes for corneal damage and treat appropriately. Immediately consult an ophtha l mologist for patients who have corneal injuries.

Ingestion Exposure Do not induce emesis

. If the vic tim is symptomatic, immediately institute emergency life support measures including the use of a cyanide antidote kit ( see Antidotes in the Prehospital Management

section above ). If the victim is alert, asymptomatic, has a gag reflex, and it has not been done previously,

consider perform ing gastric lavage

.

V omitus or gastric washings should be isolated (e.g., by attaching the lavage tube to isolated wall suction or another closed container).Hydrogen Cyanide

ATSDR • Emergency Department Management 15 Antidotes and Other Treatments Patien ts who have signs or symptoms of significant systemic toxicity should be evaluated for antidotal

treatment. There are currently two cyanide antidotal kits approved by the U.S. FDA. Use either the cyanide antidotal kit that includes amyl nitrite perles and

intravenous infusions of sodium nitrite and sodium

thiosulfate or the recently approved cyanokit that employs intravenous infusion of hydroxocobalamin ( FDA 2006; HSDB 200 7). For instructions on us e of cyanide antidotal kits, see Antidotes in the Prehospita l Management section above.

The efficacy of hyperbaric oxygen in cyanide poisoning is unproven. It has been reported to be useful

in severe cases of smoke inhalation combined with exposure to hydrogen cyanide and carbon monoxide (HSDB 2007 ).

Laborato ry Tests The diagnosis of acute cyanide toxicity is primarily a clinical one (based on rapid onset of CNS toxicity and cardiorespiratory collapse). Specific tests for the presence of cyanide in blood and urine may be useful in confirming exposure, but have limited usefulness in

acute treatment decisions. Routine laboratory studies for all exposed patients include CBC, blood glucose, and electrolyte determinations. Additional studies for patients exposed to hydrogen cyanide include ECG monitoring, determinations of serum lactate and urinary thiocyanate, chest radiography, and pulse oximetry (or ABG measurements) (Hall and Rumack 1998). S ome pulse oximeters may give spurious results in the presence of hemoglobin species other than oxyhemoglobin and deoxyhemoglobin.

In severe poisonings, venous blood is oxygenated and has a bright red color. Elevated venous PO2 and venous percent O2 saturation occurs, narrowing the gap between arterial and central venous PO2 or percent O2 saturation (Hall and Rumack 1998).

After treatment with nitrites, serum methemoglobin levels may be monitored. Whole blood cyanide tests generally require several hours and cannot be used to guide emergency treatment. However, blood cyanide levels may be useful in documenting exposure (Hall and Rumack 1998; Kruszyna et al. 1993).Hydrogen Cyanide

16 Emergency Department Management • ATSDR MRI studies may be useful in identifying the location

and extent of brain injury in patients with cyanide

induced Parkinsonian syndrome.



### Disposition and Follow- up Consider hospitalizing patients who have histories of significant exposure and are symptomatic. Whenever

infusions from a cyanide antidote kit are used, the patient should be admitted to the intensive care unit (Hall and Rumack 1998).

Delayed Effects Patients who have ingested hydrogen cyanide solutions or patients who have direct skin or eye contact should be observed in the Emergency Department for at least 4 to 6 hours (Hall and Rumack 1998).

Patient Release Patients who remain asymptomatic 4 to 6 hours after exposure may be discharged with instructions to seek medical care promptly if symptoms develop (see the Hydrogen Cyanide—Patient Information Sheet below).

Follow-up Obtain t he name of the patient’s primary care physician so that the hospital can send a copy of the ED visit to the patient’s doctor.

Survivors of a serious exposure should be evaluated for ischemic damage to the brain and heart. Patients who have serious systemic cyanide poisoning may be at risk for CNS sequelae including Parkinsonian

- like syndromes; they should be monitored for several weeks to months (Hall and Rumack 1998).

Patients who have corneal injuries should be

reexamined wit hin 24 hours.



### Reporting If a work

- related incident has occurred, you may be legally required to file a report; contact your state or local health department.

Other persons may still be at risk in the setting where

this incident occurred. If the incident occurred in the workplace, discussing it with company personnel may prevent future incidents. If a public health risk exists, notify your state or local health department or other public agency. When appropriate, inform patients that they may request an evaluation of their workplace fromHydrogen Cyanide

ATSDR • Emergency Department Management 17 OSHA or NIOSH. See Appendices III and IV for a list of agencies that may be of assistance.Hydrogen Cyanide

18 Patient Information Sheet • ATSDR 

### Hydrogen Cyanide

Patient Information Sheet

This handout provides information and follow

- up instructions for persons who have been exposed to hydrogen cyanide.

What is hydrogen cyanide? At room temperature, hydrogen cyanide is a volatile, colorless

- to

- blue liquid (also called hydrocyanic acid). It rapidly becomes a gas that can produce death in minutes if breathed. Hydrogen cyanide is used in making fibers, plastics, dyes, pesticides, and other chemicals, and as a fumigant to kill rats. It is also used in electroplating metals and in developing photographic film. Low cyanide levels can be measured in cigarette smoke.

What immediate health effects can be caused by exposure to hydrogen cyanide? Breathing small amounts of hydrogen cyanide may cause headache, dizziness, weakness, nausea, and vomiting. Larger amounts may cause gasping, irregular heartbeats, seizures, fainting, and even rapid death. Generally, the more serious the exposure, the more severe the symptoms. Similar symptoms may be produced when solutions of hydrogen cyanide are ingested or come in contact

with the skin.

Can hydrogen cyanide poisoning be treated? The treatment for cyanide poisoning includes breathing pure oxygen, and in the case of serious symptoms, treatment with specific cyanide antidotes. Persons with serious symptoms will need to be hospitalized.

Are any future health effects likely to occur? A single small exposure from which a person recovers quickly is not likely to cause delayed or long- term effects. After a serious exposure, a patient may have brain or heart damage.

What tests can be done if a person h as been exposed to hydrogen cyanide? Specific tests for the presence of cyanide in blood and urine may be useful in confirming exposure,

but have limited usefulness in acute treatment decisions . If a severe exposure has occurred, blood and urine analyses a nd other tests may show whether the brain or heart has been injured. Testing is not needed in every case.

Where can more information about hydrogen cyanide be found? More information about hydrogen cyanide can be obtained from your regional poison control center; your state, county, or local health department; the Agency for Toxic Substances and Disease Registry (ATSDR); your doctor; or a clinic in your area that specializes in occupational and environmental health. If the exposure happened at work, you ma y wish to discuss it w ith your employer, the Occupational Safety and Health Administration (OSHA), or the National Institute for Occupational Safety and Health (NIOSH). Ask the person who gave you this form for help in locating these telephone numbers.Hydrogen Cyanide

ATSDR • Patient Informa tion Sheet 19 

### Follow

- up Instructions

Keep this page and take it with you to your next appointment. Follow only the instructions checked

below.

[ ] Call your doctor or the Emergency Department if you develop any unusual signs or symptoms

within the next 24 hours, especially:

**•** difficulty breathing, shortness of breath, or chest pain

**•** confusion or fainting

**•** increased pain or a discharge from your eyes

**•** increased redness, pain, or a pus-like discharge in the area of a skin burn

[ ] No follow-up appointment is necessary unless you develop any of the symptoms listed above. [ ] Call for an appointment with Dr. ______________ in the practice of ______________________. When you call for your appointment, please say that you were treated in the Emergency Departm ent at _______________ Hospital by _____________________________ and were advised to be seen again in __________ days. [ ] Return to the Emergency Department/_______________ Clinic on (date) _______________ at

_________________________ AM/PM for a follow -up examination. [ ] Do not perform vigorous physical activities for 1 to 2 days. [ ] You may resume everyday activities including driving and operating machinery. [ ] Do not return to work for

_____ days. [ ] You may return to work on a limited basis. See instructions below. [ ] Avoid exposure to cigarette smoke for 72 hours; smoke may worsen the condition of your lungs. [ ] Avoid drinking alcoholic beverages for at least 24 hours; alcohol may worsen injury to your

stomach or have other effects. [ ] Avoid taking the following medications: _____________________________________________ [ ] You may continue taking the following medication(s) that your doctor(s) prescribed for you:

________________________________________________________________________________

________________________________________________________________________________ [ ] Other instructions: ______________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

**•** Provide the Emergency Department with the name and the number of your primary care physician so that the ED can send him or her a record of your emergency department visit.

**•** You or your physician can get more information on t he chemical by contacting: ____________________________or _______________________, or by checking out the following Internet Web sites: ________________________________________________;

____________________________________________________________________________.

Signature of patient ________________________________ Date ___________________________

Signature of physician ______________________________ Date ___________________________Hydrogen Cyanide

20 References • ATSDR 

### Refe rences

AIHA. 1994. Emergency response planning guidelines: Hydrogen cyanide. Fairfax, VA: American Industrial Hygiene Association.

ATSDR. 2006. Toxicological profile for cyanide (update ). U.S. Department of Health and Human

Service s. Agency for Toxic Substances and Disease Registry.

Drugs.com. 2007. Drug information online: Cyanokit injection. http://www.drugs.com/pro/cyanokit.html

. October 11, 2007.

EPA. 2007. Hydrogen cyanid e results. Acute Exposure Guideline Levels (AEGLs). U.S. Environmental Protection Agency. http://www.epa.gov/opptintr/aegl/pubs/results6.htm . January 12,

2007.

FDA. 2006. FDA news: FDA ap proves drug to treat cyanide poisoning. U.S. Food and Drug

Administration. http://www.fda.gov/bbs/topics/NEWS/2006/NEW01531.html

. October 11, 2007.

Hall AH, Rumack BH. 1998. Cyanide and related compounds. In: Haddad LM, Winchester JF, ed s. Clinical management of poisoning and drug overdose. 2nd ed. Philadelphia, PA: W.B. Saunders Company, 899-905.

Hartung R. 1994. Cyanides and nitriles. In: Clayton GD, Clayton FE, ed. Patty's industrial hygiene and toxicology. New York, NY: John Wiley & Sons, Inc., 3119-3127.

HSDB. 2007. Hydrogen cyanide. Hazardous Substances D ata Bank. National Library of Medicine. http://toxnet.nlm.nih .gov/cgi- bin/sis/htmlgen?HSDB . October 11, 2007.

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