We hope you found a new tox tidbit in Part 1 of “Toxic Hazards in the All-American Garage” about toxic alcohols and hydrocarbons, but there are still more hazards in the garage to discuss. Refresh your knowledge about lawn/garden products and caustics in this second issue.
Lawn and Garden Products
Fertilizers, herbicides, pesticides are a complicated category because some are virtually harmless and others are quite toxic. Do you know the differences to treat each accordingly?
Fertilizers typically have a low order of toxicity. They are meant to deliver nitrogen, phosphorus, and potassium and trace elements by using various compounds. Nitrogen, for example, is often provided by urea, urea-formaldehyde, or ammonium compounds. Some products contain nitrates, but they are usually not ingested in large enough quantities to cause methemoglobinemia. Symptoms may include oral, throat and GI irritation, nausea, and contact dermatitis.
Herbicides kill unwanted plants. Most modern options target a plant hormone or enzyme complex not found in animal species, which imparts selective toxicity and a wide margin of safety. The most commonly used herbicide used is glyphosate, which inhibits chlorophyll production, and so mammalian systemic toxicity is extremely rare. Ingestion of small amounts of ready-to-use and diluted products can cause a bad taste, oral irritation, and minor GI symptoms. Large ingestions, usually intentional, of concentrated solutions may cause significant symptoms due to the surfactant content, such as mucosal lesions, severe GI irritation, hypotension, and pulmonary edema.
The formulations typically contain a variety of secondary ingredients to enhance the product’s properties, such as antimicrobials to prevent mold and bacterial growth in the bottle. These are often contact sensitizers and can cause a poison-ivy-like allergic contact dermatitis, or perhaps the exaggerated sunburn effect of photosensitivity. Only directly-exposed skin will be affected. Dermal side effects do not indicate a systemic reaction.
Possible inhalation of the product from long periods of spraying, spraying overhead, or being in the path of wind-blown spray can cause a bitter taste in the mouth, irritation of the nose, rhinorrhea, stinging or tingling of the oral mucosa, and a raspy feeling in the throat. Lower respiratory tract involvement, such as asthmatic-like bronchospasm is not expected.
There are many classes of insect killers, of varying toxic potential to humans. Most approved for use in residential settings are not particularly dangerous. They include the large group of pyrethrins/pyrethroids,
such as found in Raid insecticide products, and neonicotinoids, such as imidicloprid found in Bayer Advanced products and some spot-on flea treatments.
Pyrethroids can induce mild paresthesia following dermal contact, which can be treated with topical application of vitamin E. Neonicotinoid exposure is largely asymptomatic, with rare reports of mild eye or skin irritation, and nausea.
Carbaryl and malathion are common representatives of the older classes of carbamate and organophosphate insecticides. The key difference is that the duration of carbamate-induced symptoms is much shorter, although they may temporarily be as severe as organophosphate poisoning.
The mechanism is inhibition of acetylcholinesterase, which causes a classic pattern of cholinergic symptoms in the autonomic and somatic motor systems (Table 1). However, children may present instead with coma, dyspnea, and flaccid limbs and limited muscarinic symptoms.
Small amounts of diluted solutions, usually < 1 %, can be tolerated with minimal symptoms. More than a lick or taste of concentrate or several mouthfuls of a dilute product can produce more significant symptoms.
Decontamination is an important step to treatment. Contaminated clothing should be removed, isolated, and washed before re-use. The patient should gently, but thoroughly wash skin and hair with soap and water. Atropine is the antidote for muscarinic symptoms: pinpoint pupils, moist skin in axillae, and respiratory difficulty due to secretions and/or bronchospasm. Atropine is not effective for muscle weakness or CNS effects. Diazepam is the treatment of choice for CNS symptoms.
Caustics include strong acids or bases that are used to clean barbeque grills and concrete, remove rust, and unclog drains. Depending on the concentration, tissue injury ranging from minor irritation to full thickness corrosion with necrosis and perforation can occur. Ingestion usually prompts immediate pain and vomiting. Eye exposure to a concentrated alkali requires prolonged irrigation for at least 30 minutes until the pH is 8-8.5, and an ophthalmology consult is recommended. Dermal exposures should also be flushed well with copious amounts of water, and the chemical burn treated as a thermal burn.
Hydrofluoric acid (HF), found in wheel cleaner, glass etching and brick cleaning products has toxicity beyond irritating/corrosive effects. Hydrofluoric acid dissociates and releases free fluoride ion as it moves through tissue. This causes tissue destruction and poses a risk for systemic effects if absorbed. Fluoride complexes with circulating unbound calcium, and induces other electrolyte imbalances which ultimately lead to malignant cardiac arrhythmia. Painful dermal exposure can be treated with irrigation and application of calcium gluconate gel. Systemic toxicity includes correction of calcium and electrolyte abnormalities, and the ACLS protocols for cardiac effects.
With so many products stored in one place, exposures to garage hazards can be difficult to sort out. Our advice to you is to call the Missouri Poison Center. Our specially trained nurses, pharmacists and medical toxicologist can provide you with the most up to date treatment advice.