Moss, a simple non-vascular plant, is generally not directly deadly or poisonous to humans. This common green growth poses no acute toxic threat if ingested or touched, with no known human fatalities directly attributed to moss poisoning.
Direct Toxicity of Moss
Moss species do not contain compounds acutely poisonous to humans. Unlike some plants that produce harmful toxins, mosses lack the cellular structures to create such substances. Moss is considered non-toxic for both humans and pets. While not a common part of the human diet, moss itself is not inherently toxic, though environmental contaminants it absorbs could pose an indirect risk.
Indirect Hazards Associated With Moss
Moss can present physical hazards, primarily by creating slippery surfaces. When moss grows on hard outdoor areas like pavements, steps, decks, or roofs, it forms a slick layer, especially when wet. This significantly reduces traction, increasing the likelihood of slips and falls. Falls caused by such slippery conditions can result in a range of injuries, from minor bruises and sprains to more severe fractures or head trauma. Beyond slipping, dense moss growth can conceal underlying trip hazards. Additionally, moss on roofs traps moisture against building materials, potentially leading to decay, mold growth, and structural damage over time, which can create indirect health or safety concerns related to the building’s integrity.
Allergies and Moss
Some individuals may experience allergic reactions to moss, though this is considered rare. These reactions are typically triggered by inhaling microscopic moss spores. Common symptoms include respiratory issues such as sneezing, a runny or stuffy nose, itchy or watery eyes, wheezing, and even an exacerbation of asthma. Direct contact with moss can also lead to skin irritation or contact dermatitis for some people with sensitive skin. Allergic reactions to moss, including Spanish moss, have been reported.
Common Misconceptions About Moss
Many misconceptions surround moss. A common myth is that moss itself is inherently slippery; however, it is often the presence of algae growing alongside moss, especially when wet, that creates the most significant slip hazard. Another misunderstanding is that moss actively harms trees or other plants by acting as a parasite. Moss simply grows on surfaces and does not draw nutrients from its host, instead absorbing water and nutrients from the atmosphere. While moss can retain moisture, it is also a misconception that its presence directly indicates or causes mold growth; healthy moss and mold are rarely found together.