Need to know
- CHOICE tested a batch of 70 dried herbs and spices from a variety of popular brands
- All samples had traces of lead and many had traces of arsenic, antimony, cadmium and mercury, with some higher than others
- Herbs and spices are consumed in small amounts and consumers shouldn't be overly concerned with the results, but are advised to try to minimise their total exposure to heavy metals found in food and in their environment
Dried herbs and spices can play a key role in all types of dishes, from sweet gingerbread to savoury curries. They're a tasty alternative to salt and they help add flavour to our favourite meals.
A recent study by our US counterpart, Consumer Reports, found that some popular supermarket herbs and spices contain contaminants such as arsenic and lead, so CHOICE was curious to see if Australian consumers are being exposed to the same issue.
We had 70 samples of seven different herbs and spices tested for heavy metals through an external NATA-accredited lab. There were traces of lead in every sample, and traces of arsenic in 86% of the samples. While some contain higher amounts of heavy metals than others, only a very high consumption of these products would lead to heavy metal toxicity.
All heavy metals are toxic to humans at higher levels. But some heavy metals, such as iron, copper, magnesium and zinc, are required for human health. Others have no health benefits.
The heavy metals associated with the most serious effects on human health are lead, arsenic, cadmium and mercury. Lead, cadmium and mercury accumulate in the body, so frequently consuming even small amounts may be harmful. Exposure to high levels of lead can cause a number of health effects such as brain damage, intellectual disabilities, heart disease, bone fractures and kidney dysfunction. Cadmium has been associated with weak bones and kidney disease.
Arsenic doesn't accumulate in the body but has been labelled by the World Health Organization (WHO) as a compound that can cause cancer. Respiratory diseases and skin problems are among the other complications that can result from chronic exposure to arsenic.
Lead, cadmium and mercury accumulate in the body, so frequently consuming even small amounts may be harmful
Dr Ayanka Wijayawardena, a heavy metals researcher at the University of Newcastle, says there are a number of factors to consider when weighing up the danger to consumers, including the total concentration in the herbs and spices, how much you ingest, how often you consume them, and how much gets absorbed by the body.
"Spices are utilised in very minute quantities in daily life. If we calculate daily or weekly intake, I assume those metal ingestions might be within safe limits," says Wijayawardena. "Having said that, we cannot completely deny any health risk at this stage as even in small quantities, the body mass index of the person exposed could also dictate the effects as well."
So even though herbs and spices usually make up a small part of most people's diets, young children, for example, would be more susceptible to their effects. People who are pregnant or breastfeeding also need to be extra cautious about lead as it could pass to developing brains and organs.
We bought 70 samples from 12 different brands of seven different herbs or spices:
- ginger (ground)
Ideally, we'd be able to test every herb and spice on the market, but we started off small not knowing what we'd find. We made an effort to test popular brands available in major supermarkets but there may have been some brands we missed and some types of herbs and spices we left out.
The following products contained the least amount of total heavy metals in their category in our test:
- Spice & Co and G-Fresh Ground Ginger
- Masterfoods Cumin
- (Aldi) Stonemill Basil
- Coles Paprika
- Spice & Co Oregano
- Woolworths Thyme.
But it's important to know that the heavy metal concentrations in any of the products can easily change between batches, so these products may not be the better performers if we were to test a new batch.
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The Australian food regulatory body Food Standards Australia New Zealand (FSANZ) sets maximum levels of heavy metals in certain food categories when it has been determined that there is a potential risk to public health.
But dried herbs and spices don't fall into any of those categories, so they only have to comply with the overall maximum levels, which are quite high – none of the herbs and spices we tested went over these blanket maximum levels set by FSANZ.
For categories like herbs and spices that are only subject to the blanket maximum levels, FSANZ states that: "Food must be safe and suitable for human consumption. For example, the concentration of contaminants and natural toxicants should be kept as low as reasonably achievable."
Aldi removed their Stonemill ground ginger from the shelves to undertake independent testing of the spice
And even though there aren't limits for heavy metals in herbs and spices, it's an interesting exercise to apply instead the limit for arsenic in salt, which is consumed in small amounts and in similar ways to herbs and spices. When we do that, the arsenic we found in our batch of Master of Spices ground ginger and Woolworth's oregano would exceed this limit.
We informed the companies that sell these herbs and spices of our findings. We heard back from Aldi, Woolworths, Coles, McCormick and Simply Organic. Aldi removed their Stonemill ground ginger from the shelves to undertake independent testing of the spice, and the other retailers who responded all mentioned the lack of guidelines for the limit of heavy metals in herbs and spices.
Every few years, FSANZ estimates Australians' dietary exposure to certain contaminants, such as heavy metals, by doing an analysis of a variety of food categories.
This is called the Australian Total Diet Study (ATDS), and in the 25th study, over 1500 samples of 88 different types of food and beverages were collected across 2013 and 2014, and combined into 508 composite samples for analysis. These don't include herbs and spices because previous exposure estimates conducted by FSANZ have not considered herbs and spices to be significant contributors to heavy metals in the diet.
Arsenic was detected in just 28% of the ATDS samples. In our test, arsenic was detected in 86% of the herbs and spices we sent to the lab. The highest arsenic concentration (in a non-seafood source) that came from the ATDS was a rice-based breakfast cereal, which contained half the level of arsenic that we discovered in some of the spices in our test.
Lead was detected in 15% of the samples in the FSANZ study, but was detected in all of our herb and spice samples
Lead was detected in 15% of the samples in the FSANZ study, but was detected in all of our herb and spice samples. The average concentration in our herbs and spices was five times higher than that of mussels, the food found to have the most contamination.
Even though we tend to consume smaller quantities of herbs and spices compared with other foods, there's a case for further investigation of this category by including it in the Australian Total Diet Study.
Having seen the results of our tests, FSANZ told us that it "notes the findings of the CHOICE investigation" and is "intending to look at contaminants as part of the next ATDS and will consider the outcomes of this analysis in planning this work".
Pollution of heavy metals is an increasing problem worldwide due to population growth and land use changes.
Heavy metals can enter the food chain throughout the growing, manufacturing, packaging or storage stages of food production.
During the growing stage, polluted soil, air or water can contaminate herb and spice plants. The soil, air or water can be polluted by inadequately treated sewage, contaminated groundwater, pesticides and industrial activity.
Herbs and spices sold in Australian supermarkets are generally not produced in Australia, which makes it harder to know what they've been exposed to before ending up on our shelves. Soil testing and sewage treatment standards may differ internationally, and the brands may use different suppliers from batch to batch.
The herbs and spices we found to generally have lower amounts of lead and arsenic in our test were cumin, oregano, paprika and turmeric
Associate Professor Suzie Reichman, from the University of Melbourne, has published studies about heavy metals in foods. She suggests that some of the explanations as to why heavy metals were detected in our test may have been because they're grown on farms with heavy road use or industrial processing nearby, or that they're being grown on contaminated soil.
According to Reichman, some of these heavy metals, such as antimony, can come from vehicle brake pads, nearby mines or untreated sewage, and that our results raise questions about the manufacturing process and whether the plants have been washed before drying.
This isn't the first time heavy metals have been found in imported goods. A report by broadcaster SBS showed heavy metals and harmful pesticides found in products sold in South Asian grocery stores across Australia, and Reichman's study into kids' rice snacks available in Australian supermarkets found arsenic above EU guidelines for children in products imported from the USA and products made in Australia (products in the study from Europe, Thailand and China came in under the guidelines).
Heavy metals should be kept as low as possible in the diet. The herbs and spices we found to generally have lower amounts of lead and arsenic in our test were cumin, oregano, paprika and turmeric. Not all heavy metals were found in the batches we tested, and mercury and tin were present in only negligible amounts.
Herbs and spices make up a small part of the average person's diet, and a serving is small at about half a gram or less. But you need to consider how many servings you have, how many spices you use in one meal, and how many times a week you have them and of course, clean all fresh produce thoroughly before consuming.
Consider your exposure to heavy metals from your total diet and even your whole environment. You may be exposed to heavy metals through paint, pollution and household items.
FSANZ has more information about heavy metals in foods and their risks.
Stock images: Getty, unless otherwise stated.