The metal in jewelry is not regulated in North America the way it is in the European Union. So there isn't any oversight to protect us from sellers who misrepresent 925 (Sterling Silver) and other metals and may include toxic metals. 925, or Sterling Silver, means that 92.5% of the metal is pure silver and the remaining 7.5% is copper. Most cheap imported jewelry, which includes jewelry targeted to children, including those stamped 925 (fraudulently because it is not 925 and may in fact not contain any silver at all) contains unknown metals. When tested, alarming metals are detected and in amounts that are dangerous. Cadmium is the most harmful toxic metal and is strictly controlled in Europe. Cadmium may be used in the processing of silver but due to its toxicity, the EU allows for only .01% Cadmium in jewelry. As there are no such guidelines here, Cadmium is often found and at times in amounts that range from 500 to 3000 times the acceptable EU amount. So children in North America may be absorbing toxic levels of Cadmium through their skin or mouths.
Lead is another metal found in imported cheap jewelry, particularly children's jewelry:
Lead is a toxic metal, which doesn’t break down in the environment and accumulates in our body. High levels of lead have been found in jewelry, especially inexpensive children’s jewelry.
Exposures to lead can lead to a number of health problems, including:
joint and muscle weakness
and even death
Children 6 years old and under are most at risk because their bodies are growing quickly. Jewelry containing lead poses a particular concern because children are prone to placing jewelry in their mouths, which can result in absorption of dangerous levels of lead. Lead poisoning is blamed for the death of a four year old in Minnesota who swallowed a lead containing jewelry charm." (California Department of Toxic Substances Control. dhttps://dtsc.ca.gov)
Similarly, Nickel is often found in imported cheap jewelry. Most people have varying levels of skin sensitivity to Nickel which develops into a Nickel allergy causing contact dermatitis.
So how do we protect ourselves. Most of the problem jewelry comes from China and India. Silver from Thailand is much more reliable but the best silver comes from North America, Italy and Israel. Therefore the easiest way to avoid toxic metals is to not wear jewelry from China or India. If the country of origin is not identified, then ask the seller. A responsible jewelry seller will know where the jewelry has been made. If they do not know, then assume it is not safe. Not all jewelry from China is dangerous. One supplier that I asked where their silver came from provided the following answer:
China actually has very strict sterling silver laws and reputable factories which adhere to these laws. Our Amoracast line is manufactured in China and is superb in quality and material. In exercising due diligence, we only source from ISO certified factories which ensure employees are paid a living wage. As an extra step we assay test all our products by a third party.(Gail at Stones and Findings in Toronto, firstname.lastname@example.org). This response was re-assured me that my customers would be safe if I used chains or other jewelry components from this company in my jewelry pieces.
For the sake of your health and conscience, find a jeweller or jewelry provider that you trust and have established that they adhere to ethical, environmental and safety standards. Then you don't have to worry when you need or want to purchase jewelry for yourself or others, particularly children. Safe good jewelry for children is not cheap, but it can be reasonably priced. You may choose to purchase less jewelry in order to ensure that it is safe. Most children are not that interested in wearing jewelry, particularly if they are under 6 years old, and are wearing it to please their parents or whoever bought it for them. Just mention to friends or family that might give your child jewelry that due to safety concerns, you would prefer they not gift jewelry to your child.
In the end, your guiding principle should be: avoid children's jewelry altogether. For adult jewelry, if the price looks too good to be true (like the prices for jewelry on Wish.com for example) then it is unlikely to be safe. Be informed and err on the side of caution.