Sept 16, 2016: Back to School – What are the dangers of borax slime and homemade salt dough?

Arts and crafts are a staple of young children’s education, encouraging imagination and creativity. The best teachers go the extra mile and bring in supplies for their students to make their own take home craft. Many times these crafts contain substances that could be potentially toxic with ingestion.

Boric acid is an inorganic acid found in many household products including some pesticides, laundry soaps, and contact lens solutions. It is used as a main ingredient in home-made recipes for silly slime. The mechanism of toxicity is not well described in the literature with dermal exposure and acute ingestion limited to irritation without caustic injury. Acute ingestions can cause nausea, vomiting, and diarrhea, similar to gastroenteritis, but are typically well tolerated. More serious exposures occur with chronic exposure over several days. Patients with chronic exposures present with nausea, vomiting (characteristic blue-green hue), and diarrhea. After initial symptoms, an erythroderma delayed by one to two days post ingestion occurs, and is often confused for toxic epidermal necrolysis. More serious symptoms include CNS agitation, seizures, coma, hepatotoxicity, acute kidney injury, and cardiovascular collapse. Treatment is symptomatic and supportive once the offending agent has been stopped.

Home-made play dough is a popular craft, often described as safer for children on common social media sites. These recipes call for ½ to 2 cups of table salt per dough. In an abstract published in Clinical Toxicology for the 2016 North American Congress of Clinical Toxicology, the authors selected three of the most popular and reposted recipes for home-made play dough to make in their lab. The results are as follows:


Amount of Table Salt Required


Weight of Table Salt (grams)

Weight of the Final Product (grams)

Percentage of Dough Estimated to be Table Salt

Table Salt per Tablespoon of Dough


Recipe A

0.33 Cup

101.5 g

471.0 g


3.93 g

Recipe B

0.5 Cup

163.3 g

512.5 g


5.71 g

Recipe C

1.5 Cups

474.1 g

1589.1 g


5.36 g

Table 1: Calculations of table salt per tablespoon of dough

The authors conclude that one tablespoon of dough from recipe B and C would put a 10 kg child in the toxic range for table salt ingestion (5 to 10 grams) increasing the risk for confusion, lethargy, and seizures from hypernatremia.

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This question prepared by: Nena Bowman, PharmD, SPI (Specialist in Poison Information) Tennessee Poison Center



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