The Eastern Red Cedar (Juniperus virginiana) is a common North American tree used in landscaping, aromatic wood products, and essential oil extraction. Its wide distribution and strong, insect-repellent scent often raise questions about its safety for humans and animals. Whether the plant is toxic depends on the form of the cedar and the route of exposure, such as contact, inhalation, or ingestion. Determining the level of risk requires understanding the source and concentration of the plant’s natural chemicals.
Identifying the Toxic Compounds
The toxicity of Eastern Red Cedar stems primarily from volatile oils present in the wood, berries, and leaves. These aromatic compounds are complex mixtures of terpenes, which give the cedar its characteristic smell. Two notable compounds are thujone and cedrene. Thujone is a known neurotoxin found particularly in the leaves and essential oil. Cedrene and cedrol (its alcohol form) are irritants responsible for the wood’s insect-repelling properties. These compounds are released in concentrated form during oil extraction or when the wood is processed into sawdust.
Human Exposure and Symptoms
Human exposure typically occurs through three pathways, each causing different symptoms.
Skin Contact
Direct skin contact with the wood or concentrated essential oils can trigger contact dermatitis. This allergic reaction often appears as a red, itchy rash, sometimes with small bumps or blisters.
Inhalation
Inhalation of airborne particles is common for woodworkers or those exposed to high concentrations of pollen. Breathing in fine dust from processing the wood can cause respiratory irritation, manifesting as coughing or exacerbating asthma symptoms. The pollen, often associated with “cedar fever,” can also trigger allergic reactions like nasal congestion, sneezing, and wheezing.
Ingestion
Ingestion of the plant, especially the highly concentrated essential oil, poses the most severe risk. Ingesting large amounts of the oil can lead to serious toxicity symptoms, including severe gastrointestinal distress, vomiting, convulsions, and potential neurological damage due to thujone. Consuming large quantities of raw berries or leaves may result in mild symptoms like diarrhea.
Risks to Household Pets and Livestock
Eastern Red Cedar poses a mild to moderate toxicity risk to household pets, such as dogs and cats, primarily through ingestion. If a pet chews on wood chips or consumes the small, blue, berry-like cones, the volatile oils can cause gastrointestinal upset. Symptoms typically include vomiting, diarrhea, and lethargy; a veterinarian should be consulted if large amounts are consumed.
Livestock Risks
The risk is heightened for livestock, particularly horses housed near where the tree grows. Ingestion of the plant material by horses can be serious due to the thujone, which is toxic to the nervous system. While horses usually avoid the plant, consumption may lead to neurological problems like ataxia (loss of muscle coordination). Consumption of large quantities of Juniperus foliage by grazing animals may lead to severe digestive issues or reproductive problems, as observed in cattle. Preventing access to the plant is the most effective safety measure for all grazing livestock.