Health Canada has just proposed a limit on cadmium in children’s jewelry of 130 ppm (0.013%), which is lower than the limit for lead concentrations. This limit was imposed because after a limit was established for lead, manufacturers started using cadmium instead. Several pieces of jewelry tested over the last couple of years have been almost pure cadmium, but in most cases these items remained on the market because there is currently no regulatory mechanism by which Health Canada can force them to be recalled and the sellers refused to voluntarily recall them (and yet there is still a lot of political resistance to proposed regulations that would give Health Canada the power to force a recall…).
So what’s the concern with cadmium, and is it really more toxic than lead? Read on…
Cadmium in its metal form is a silver-white metal that is very soft and malleable. It isn’t normally found as a pure metal naturally, but rather as a component of zinc ores. Canada is one of the largest producers of cadmium, primarily in Ontario, Quebec and New Brunswick, with most of it being exported. It is used in batteries, coatings, pigments, as a plastic stabilizer, and in various metal alloys, and can be found in many common consumer products. Cadmium isn’t a very large component of natural soils, and most cadmium in the environment is a result of human activity.
The main health effect from cadmium discussed in media reports is cancer, and cadmium is classified as a confirmed human carcinogen by the International Agency for Research on Cancer (their old assessment is here; it is currently being updated). The primary cancer effect from cadmium is lung cancer from occupational exposures to cadmium fumes and dust, however, which isn’t really relevant for the general population. There isn’t really any evidence of cadmium causing cancer in humans from ingestion, although there is some limited evidence in animal studies that suggests it could be associated with leukaemia, testicular cancer and prostate cancer, but only in animals with low dietary zinc intake.
The most important effect outside of occupational exposures is actually kidney damage, which has been observed both in humans and in animal studies. Health Canada currently suggests a maximum chronic cadmium intake of 1 microgram per kilogram body weight per day (μg/kg/d) from oral (ingestion) exposure. Similarly, the US Environmental Protection Agency has an oral reference dose (essentially the maximum dose which, over a lifetime of continuous exposure, is not expected to result in adverse effects) of 1 μg/kg/d from food or 0.5 μg/kg/d from water.
Everyone is exposed to some cadmium, mostly from food, although tobacco smoke can also be a major source. For most people the typical exposure doesn’t exceed these recommended limits, but it can be fairly close, particularly for young children; for example, it has been estimated that a typical Canadian toddler has an exposure of about 0.74 μg/kg/d (mainly from food). These exposure estimates do not include exposures from consumer products such as children’s jewelry, however, so even a small amount of additional exposure is considered to be a concern.
As for whether cadmium is more toxic than lead – that’s far from resolved. There’s still a lot of debate about lead toxicity, and in particular its effects on brain development in young children, with some people arguing that there may not be a “safe” dose. Neither of these substances should really be in children’s jewelry.
So, what can you do to minimize exposure? The best thing right now is just to avoid really cheap children’s jewelry, particularly anything from dollar stores (which are notorious for having unsafe products); definitely don’t let young children who might be more inclined to put it in their mouths have it.