Substance The primary hazard associated with giant hogweed lies in its sap, which contains furocoumarins or psoralens[1]. These phototoxic compounds are found throughout the plant, with the highest concentrations notably present in its fruits, leaves, and stem[1].
Importantly, the sap can retain its toxicity on
exposed clothing for several hours after contact[1].
The concentration of these phototoxic compounds in giant hogweed
is highest during the months of June, July, and August, aligning
with periods of increased outdoor human activity[1].
Common Name Giant hogweed (Heracleum mantegazzianum) is a highly invasive flowering weed
Massive Size: A towering
monocarpic perennial, reaching 3–5.5 meters tall with large leaves and white
umbrella-shaped flowers.
[1][2]
Origin & Spread: Native
to the Caucasus, introduced to the UK in the 19th century, and later
spread across Europe, the U.S. (1917), and Canada (1949).
[1][2]
Invasive Status: Listed as
an invasive alien species of Union concern; ranked 22nd among Europe’s top 149
invasive species.
[2]
Habitat Range: Thrives in
diverse areas—riversides, roadsides, fields, and even seashores—due to high
adaptability.
[1][2]
Czech Distribution Example:In
the Czech Republic, 84.7% grow in fields, 13.7% in forests, and just 1.6% in
urban areas.
[2]
Involving System Contact with giant
hogweed sap primarily affects the following systems:
●
Skin: Leading to
a severe inflammatory reaction known as photophytodermatitis[1][2]. This is a non-immunologic form of dermatitis[1].[3]
●
Eyes: Direct eye
contact with the sap can result in blindness[1][2].
●
Respiratory
System: Inhalation of plant traces may cause obstructive pulmonary symptoms[1].
Presentations
Photophytodermatitis is triggered when UVA light activates furocoumarins
(psoralens) in the plant sap, producing reactive oxygen species and DNA
intercalation, leading to cell death and impaired healing [2]. Symptoms may
begin within 15 minutes of exposure, with visible signs like erythema and
edema typically appearing after 24 hours and peaking at 72 hours [1][2].
Skin injury ranges from mild redness to full-thickness chemical
burns requiring debridement and grafting [1][2][4]. Severity
increases with greater sap contact, sun exposure, humidity, heat, infection,
and lack of protective clothing. Long-term hyperpigmentation can persist for
weeks [1].
Photodistribution
and Case Example:
The rash mainly appears on sun-exposed skin [2]. A 27-year-old landscaper
trimming tall giant hogweed without protection developed severe blistering on
his arms and neck, including large bullae (3–4 cm) and marked edema; his
coworkers had milder reactions [1].
Antidote/Treatment
Effective management of giant hogweed exposure
involves immediate action and symptomatic treatment:
●
Immediate
Response: Upon contact with giant hogweed, it is crucial to immediately avoid any further UV exposure[1]. The affected area should be thoroughly rinsed with soap and water[1][2]. It is imperative to avoid UV radiation for
at least 48 hours following exposure[1].
●
Topical
Treatment: For mild reddening or erythema, a topical steroid can be applied
to the affected area[1].
●
Pain
Management: Pain can be alleviated by using a nonsteroidal anti-inflammatory drug[1].
●
Blister Management:
○
Small blisters can be carefully punctured and
drained[1].
○
However, for large blisters, extensive
epidermal-dermal separation, or large areas of detached epidermis, the
recommendation is to simply cleanse and dress the affected area without
puncturing[1].
●
Systemic
Treatment: In cases of moderate to severe inflammation, an oral steroid may be prescribed. For
instance, a patient was successfully treated with oral prednisone 70 mg daily
(1 mg/kg/d), with the dosage gradually decreased by 10 mg every three days
until the course was complete[1].
●
Surgical
Intervention: Full-thickness
chemical burns may necessitate surgical
debridement and skin grafting[1].[5]
●
Post-Treatment
Care: To manage open areas, mupirocin ointment can be
applied, while petroleum jelly is recommended for intact skin[1]. Patients are also advised to practice strict photoprotection for both the
immediate and long-term future[1].
Disposition
The prognosis for giant hogweed phytophotodermatitis,
with appropriate treatment, can be favorable. In one clinical case, the severe
phytophotodermatitis dramatically improved within several days, with complete
resolution observed in one week. Postinflammatory hyperpigmentation, a
common sequela, resolved after several weeks[1].
However, the broader implications of giant hogweed
extend beyond individual health outcomes, encompassing significant economic and
public health impacts across regions[1][2].
Public
Health Impacts:
●
The large size and "charismatic"
nature of the plant make it particularly dangerous for unsuspecting visitors
or tourists, contributing to the risk of injury. Dense populations can
physically impede access to valued amenity areas and reduce visibility along
roadsides[2].
Management
and Prevention Strategies:
Due to the phototoxicity of giant hogweed sap,
control requires trained personnel with protective gear [1]. The plant is extremely invasive, producing up to 50,000 seeds per plant with a ~90% germination rate,
making eradication long-term and resource-intensive [2].
Misidentification with native plants like Angelica or wild parsnip complicates
detection [2]. In high-traffic areas,
authorities may need to restrict public
access to reduce human contact risk [2].
Although
giant hogweed’s spread in North America has
been relatively slow, European cases show that delayed action
can lead to exponential invasion, escalating
both health and economic impacts [1]. Early detection and
rapid response are essential for cost-effective control.
Regions bordering known invasion zones (e.g., Kentucky, Missouri, Tennessee)
and underreported areas (e.g., New Hampshire) should stay vigilant to prevent
widespread establishment [2].
References
- Cuddington
K, Sobek-Swant S, Drake J, Lee W, Brook M. Risks of giant hogweed
(Heracleum mantegazzianum) range increase in North America. Biol
Invasions. 2022;24:299–314.
- Flanagan
KE, Blankenship K, Houk L. Botanical Briefs: Phytophotodermatitis Caused
by Giant Hogweed (Heracleum mantegazzianum). Cutis. 2021;108:251-253.
- Lagey
K, Duinslaeger L, Vanderkelen A. Burns induced by plants. Burns. 1995 Nov;21(7):542-3.
doi: 10.1016/0305-4179(95)00026-8. PMID: 8540985.
- .Chan
JC, Sullivan PJ, O'Sullivan MJ, Eadie PA. Full thickness burn caused by
exposure to giant hogweed: delayed presentation, histological features and
surgical management. J Plast Reconstr Aesthet Surg. 2011 Jan;64(1):128-30.
doi: 10.1016/j.bjps.2010.03.030. Epub 2010 Apr 15. PMID: 20399165.
- Baker
BG, Bedford J, Kanitkar S. Keeping pace with the media; Giant Hogweed
burns - A case series and comprehensive review. Burns. 2017
Aug;43(5):933-938. doi: 10.1016/j.burns.2016.10.018. Epub 2016 Dec 29. PMID: 28041748
