Slime is a popular non-Newtonian fluid toy, captivating users with its unique, malleable texture. This compound, often a staple in homes and classrooms, offers an engaging sensory experience. Its widespread use, particularly among young children, raises questions about the safety of its ingredients and long-term handling. Understanding the chemical components, potential contaminants, and physical risks is important for determining if the toy is safe for home play.
The Chemical Safety Concern: Boron Compounds
The unique texture of slime is achieved through a chemical reaction requiring a polymer activator, typically a boron compound like sodium borate (Borax) or boric acid. This activator causes the long chains of polyvinyl acetate (PVA) in glue to cross-link, forming the characteristic gel. Using high concentrations of borax powder, particularly in homemade recipes, poses a hazard.
Boron compounds can cause irritation to the skin, eyes, and respiratory system upon direct exposure. Dermatitis and chemical burns have been reported when recipes contained high, undiluted amounts of the activator. Ingestion presents a serious toxicity risk, potentially leading to symptoms like vomiting, nausea, and diarrhea.
Regulatory bodies have established strict limits on soluble boron migration from children’s toys. The European Union’s Toy Safety Directive sets the limit for boron migration in sticky toy material at 300 milligrams per kilogram (mg/kg). Many commercial and unregulated slimes have been found to exceed this safety threshold, sometimes by more than 12 times. Excessive exposure to high levels of boron is linked to reproductive health concerns in long-term, high-dose scenarios.
Toxicity Risks from Colorants and Additives
Beyond the primary activator, secondary ingredients used to enhance the toy’s appeal can introduce additional chemical hazards. Unregulated or non-food-grade colorants, pigments, and dyes, particularly those used in imported or craft-based slimes, may contain toxic heavy metals. These metals, such as lead and cadmium, are sometimes present in low-quality coloring agents and can pose a systemic toxicity risk if the slime is accidentally ingested.
Other chemical components that are frequently present include preservatives like methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT). These chemicals are used to extend the product’s shelf life but are known contact allergens and skin sensitizers. Exposure to high concentrations of these isothiazolinone preservatives can lead to allergic contact dermatitis, causing skin irritation and rashes.
Physical hazards are also introduced by popular add-ins like foam balls, plastic beads, and glitter. While glitter is a microplastic that is generally non-toxic, small, hard, or round components can pose a significant choking hazard, especially to children under three years old. Ingestion of larger items or materials like water-absorbing gel beads, which are sometimes mistaken for a slime additive, can lead to dangerous intestinal blockages as they expand inside the body.
Understanding Microbial Contamination
Slime’s composition of water, glue, and various organic additives makes it an ideal environment for microbial growth. This moist, sticky, and nutrient-rich environment encourages the colonization of bacteria and mold. The risk of contamination increases significantly when the product is handled frequently, left exposed to the air, or stored in a non-airtight container.
Tests have shown that some commercial slimes contain alarmingly high levels of total microbial counts, in some cases exceeding recommended limits by thousands of times. The presence of excessive bacteria, including potentially harmful types like Enterobacteriaceae, can lead to hygiene-related health issues. Handling highly contaminated slime may increase the likelihood of skin infections, particularly if the user has cuts or abrasions on their hands. Furthermore, the growth of mold or certain bacteria can trigger allergic reactions in sensitive individuals, leading to skin and respiratory symptoms.
Guidelines for Safe Slime Play
To minimize the risks associated with this popular toy, strict supervision is recommended, especially for children under the age of six, to prevent accidental ingestion of the slime or its small additives. Establishing a routine of thorough handwashing both before and immediately after playing with the compound is necessary to limit the transfer of chemicals and microbes.
For pre-made products, only purchase slimes that display clear labeling indicating compliance with established safety standards. Consumers in the EU should look for products that meet the Toy Safety Directive limits for boron migration.
Homemade slime can be made safer by substituting pure borax powder with alternatives like contact lens solution combined with baking soda, which uses a lower, more controlled amount of the borate compound. Other borax-free recipes using cornstarch, shaving cream, or psyllium husk can eliminate the boron risk entirely. All slimes should be stored in an airtight container to slow down microbial growth, and any product that develops a foul odor or visible mold should be immediately discarded.