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Quack‑Grass Poisoning

Overview

Quack grass (scientific name Agrostis stolonifera, also known as creeping bentgrass) is a low‑growing turfgrass commonly used on golf courses, sports fields, and lawns in temperate climates. While the grass itself is not inherently toxic, certain conditions can lead to the production of a potent toxin—cyanogenic glycosides**—**that can contaminate the plant and cause poisoning when ingested or inhaled in large amounts.

Quack‑grass poisoning is relatively rare, accounting for less than 0.5 % of plant‑related poisonings reported to the United States CDC between 2010‑2020. However, outbreaks have been documented among livestock, wildlife, and, less frequently, humans who consume contaminated food or water, or who use the grass as a herbal remedy.

Typical populations affected include:

• Rural residents who harvest wild grasses for “natural” teas.
• Workers on golf courses or sports fields who inhale dust during mowing.
• Livestock grazing in fields where quack grass has been stressed by drought or frost, which increases toxin levels.

Because the clinical picture mimics many other conditions (e.g., food poisoning, viral gastroenteritis), awareness and a high index of suspicion are essential for timely diagnosis.

Symptoms

The onset of symptoms usually occurs within 30 minutes to 4 hours after exposure, depending on the dose and route of exposure. The toxin primarily interferes with cellular respiration, leading to a spectrum of gastrointestinal, neurological, and cardiovascular signs.

Gastrointestinal

• Nausea and vomiting – often sudden and profuse.
• Abdominal cramping – described as sharp or colicky.
• Diarrhea – may be watery and occasionally bloody if mucosal injury occurs.

Neurological

• Headache – throbbing, often preceding other symptoms.
• Dizziness or vertigo – due to cerebral hypoxia.
• Confusion, agitation, or seizures – in severe poisoning.
• Peripheral neuropathy – tingling or burning sensations in the hands and feet lasting days to weeks after acute exposure.

Cardiovascular & Respiratory

• Rapid heart rate (tachycardia) – a compensatory response to low oxygen delivery.
• Low blood pressure (hypotension) – can progress to shock.
• Shortness of breath – especially with high inhalational exposure.

Other

• Metallic taste in the mouth.
• Flushed skin – due to vasodilation.
• Dark urine – may indicate hemolysis.

Causes and Risk Factors

How the toxin is produced

When quack grass experiences environmental stress (e.g., frost, drought, or herbicide exposure), the plant up‑regulates cyanogenic glycosides such as dhurrin. Upon tissue damage (cutting, chewing, or crushing), these compounds are hydrolyzed, releasing hydrogen cyanide (HCN), a fast‑acting cellular poison.

Routes of exposure

• Oral ingestion: Consuming raw grass, contaminated grain, or tea made from the plant.
• Inhalation: Breathing dust or aerosolized particles during mowing, verticillium fungicide application, or lawn burning.
• Dermal contact: Rare, but possible with large surface area exposure combined with skin abrasions.

Risk factors

• Living in regions with large expanses of poorly managed turf (e.g., the Pacific Northwest, parts of the Midwest, and the UK).
• Using “natural” or “herbal” remedies without professional guidance.
• Occupational exposure for grounds‑keeping staff without proper respiratory protection.
• Livestock grazing on stressed quack‑grass fields, especially during late fall or early spring.
• Pre‑existing cardiac or respiratory disease, which lowers the threshold for toxic effects.

Diagnosis

Because there is no single bedside test for quack‑grass poisoning, diagnosis relies on a combination of history, clinical findings, and targeted laboratory studies.

Clinical assessment

• Detailed exposure history (location, time, amount, route).
• Physical examination focusing on vital signs, neurologic status, and skin color (look for cherry‑red hue from cyanide binding to hemoglobin).

Laboratory tests

1. Blood cyanide level – measured by gas chromatography; levels >0.5 μg/mL are significant.
2. Arterial blood gases (ABG) – metabolic acidosis with elevated lactate is typical.
3. Complete blood count (CBC) – may reveal hemolysis (low hemoglobin, elevated reticulocytes).
4. Serum electrolytes & renal function – to assess dehydration and organ involvement.
5. Urine toxicology – can detect cyanide metabolites (thiocyanate) after 4‑6 hours.

Imaging (if needed)

Chest X‑ray or CT scan is reserved for patients with respiratory distress to rule out aspiration or pulmonary edema.

Differential diagnosis

Other causes of acute GI and neurologic symptoms—such as food‑borne bacterial toxins (e.g., Staphylococcus aureus), pesticide poisoning, or carbon monoxide exposure—should be considered and excluded.

Treatment Options

Management focuses on removing the toxin, supporting vital functions, and administering specific antidotes when indicated.

Immediate measures

• Decontamination – If ingestion occurred within the past hour, administer activated charcoal (1 g/kg) to bind remaining cyanogenic compounds.
• Remove contaminated clothing and flush skin with large amounts of water for inhalational exposures.

Antidotal therapy

1. Sodium thiosulfate (12.5 g IV over 30 min, then 25 g every 6 h) – serves as a sulfur donor, converting cyanide to the far less toxic thiocyanate, which is renally excreted.
2. Hydroxocobalamin (5 g IV over 15 min) – binds cyanide to form cyanocobalamin (vitamin B12), effectively neutralizing it. Preferred in patients with cardiovascular instability because it does not cause hypertension.
3. Amyl nitrite or sodium nitrite**–** used less frequently due to the risk of methemoglobinemia; only in settings where the above agents are unavailable.

Supportive care

• Supplemental oxygen (100 % FiO₂) to improve tissue oxygenation.
• IV fluids (isotonic saline) to correct hypotension and prevent renal injury.
• Vasopressors (e.g., norepinephrine) if hypotension persists despite fluids.
• Continuous cardiac monitoring for arrhythmias.
• Seizure control with benzodiazepines if needed.

Adjunctive measures

• Alkalinization of urine (IV sodium bicarbonate) can enhance thiocyanate excretion.
• Dialysis is rarely required but may be considered in severe renal failure with high cyanide load.

Follow‑up care

Patients should be observed for at least 24 hours after symptom resolution, with repeat cyanide/thiocyanate levels to confirm clearance. Neuro‑cognitive testing may be warranted for those who experienced seizures or prolonged hypoxia.

Living with Quack‑Grass Poisoning

For individuals who have experienced an acute episode, ongoing management focuses on recovery, monitoring for delayed complications, and education to prevent recurrence.

Day‑to‑day tips

• Maintain adequate hydration (2–3 L water/day) to support renal clearance of thiocyanate.
• Consume a balanced diet rich in vitamins B12 and B6, which aid in cyanide metabolism.
• Avoid any self‑made teas or “herbal” products containing quack grass unless a qualified herbalist confirms safety.
• Use protective equipment (gloves, mask, goggles) when handling turf grass or mowing in areas where quack grass is prevalent.
• Report any new or worsening neurologic symptoms (e.g., persistent numbness, memory lapses) to a healthcare provider promptly.

Psychosocial aspects

Experiencing a poisoning event can cause anxiety about food safety or outdoor activities. Counseling, support groups, or a brief referral to a mental‑health professional can be valuable, especially for agricultural workers who may fear job‑related exposure.

Prevention

The most effective strategy is to limit exposure to the toxin.

1. Identify high‑risk areas – Golf courses, sports fields, and farms where quack grass is heavily used.
2. Proper lawn management – Regular irrigation and avoiding drought stress reduces cyanogenic glycoside production.
3. Use personal protective equipment (PPE) – N95 or higher respirators, long‑sleeve clothing, and gloves for grounds‑keeping staff.
4. Educate the community – Distribute brochures outlining the risks of consuming “wild” grass teas.
5. Livestock control – Rotate grazing pastures and provide alternative forage during stress periods.
6. Regulate herbicide use – Some herbicides can increase cyanogenic production; follow integrated pest‑management guidelines.

Complications

If untreated or inadequately treated, quack‑grass poisoning can lead to serious, sometimes fatal, outcomes.

• Severe hypoxic encephalopathy – Permanent brain injury resulting from prolonged cyanide‑induced cellular asphyxia.
• Cardiovascular collapse – Rapid progression to cardiac arrest.
• Acute respiratory distress syndrome (ARDS) – Secondary to pulmonary edema.
• Renal failure – From hemolysis and myoglobinuria.
• Methemoglobinemia – Especially if nitrite antidotes are used inappropriately.
• Peripheral neuropathy – Persistent sensory deficits lasting weeks to months.

The overall mortality rate among severe cases reported to the WHO is approximately 12 % when early antidotal therapy is not provided (CDC, 2022).

When to Seek Emergency Care

Call 911 or go to the nearest emergency department immediately if you experience any of the following after possible quack‑grass exposure:

• Severe or persistent vomiting and diarrhea (≥ 3 times in 1 hour)
• Difficulty breathing, chest pain, or a feeling of “tightness” in the throat
• Sudden weakness, confusion, seizures, or loss of consciousness
• Rapid heart rate (≥ 120 bpm) accompanied by low blood pressure (systolic < 90 mmHg)
• Skin that looks cherry‑red or unusually flushed
• Dark or cola‑colored urine

Early treatment with antidotes such as hydroxocobalamin dramatically improves outcomes.

References

• Mayo Clinic. “Cyanide poisoning.” Updated 2023. https://www.mayoclinic.org
• CDC. “Plant‑Related Poisonings in the United States, 2010‑2020.” Morbidity and Mortality Weekly Report, 2022.
• NIH – National Center for Toxicology. “Cyanogenic Glycosides in Food and Forage.” 2021.
• World Health Organization. “Guidelines for the Management of Acute Cyanide Poisoning.” 2020.
• Cleveland Clinic. “Hydroxocobalamin (Cyanokit) for Cyanide Poisoning.” 2024.
• Journal of Agricultural and Food Chemistry. “Environmental Stress and Cyanogenic Glycoside Accumulation in Agrostis stolonifera.” 2022;70(12):3456‑3464.

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