Marine biotoxins and climate change

I worry about food safety and so it seems do 60% of respondents in a global survey involving 150,000 people in 142 countries. However, while they are mostly concerned about the safety of the current food supply, I worry about the impact of climate change in worsening the food safety situation. We have already covered the impact of climate change on the accumulation of heavy metals and growth of moulds producing mycotoxins.

But of course there is more.

In this last blog in the series covering the food safety impact of climate change we will look at increases in the presence of marine biotoxins produced by blooms of harmful algae.

Toxins produced by some algal species

During recent decades, there has been an apparent increase in the occurrence of harmful algal blooms in many marine and coastal regions. Changes in climate may be creating a marine environment particularly suited to the growth of harmful species of algae. Two major functional groups of marine algae, or phytoplankton, are involved in causing toxic blooms – diatoms and dinoflagellates. There are also toxic cyanobacteria, sometimes called blue-green algae, that are not strictly speaking algae but very similar in action.

Certain toxins produced by these organisms are particularly dangerous to humans. A number of illnesses are caused by ingesting seafood contaminated by the toxins.

The most important harmful algae and their poisoning syndromes include diatoms from the genus Pseudo-nitzschia (amnesic shellfish poisoning), and species of dinoflagellates from the genera Alexandrium, Pyrodinium, and Gymnodinium (paralytic shellfish poisoning), Karenia (neurotoxic shellfish poisoning), Dinophysis and Prorocentrum (diarrhetic shellfish poisoning), and Gambierdiscus (ciguatera fish poisoning). There are also cyanobacteria that produce a range of toxins that can affect humans drinking or swimming in contaminated water causing a similar range of symptoms. Their toxins include microcystin, nodularin, cylindrospermopsin, anatoxin-a, anatoin-a(s), lyngbyatoxin and saxitoxins.

As the names of the syndromes imply the toxins can cause memory loss, digestive problems, seizures, lesions and skin irritations, and finally paralysis that may include the respiratory system. Indeed an impressive list.

Some of these toxins can be acutely lethal and are among the most powerful natural substances known. They affect fish, birds and mammals including humans. Because these toxins are tasteless, odourless, and heat and acid stable, normal screening and food preparation procedures will not prevent intoxication.

Increase in the growth of harmful algae

Dinoflagellate abundances have increased to the detriment of diatom populations in some marine ecosystems linked to increases in sea surface temperatures. This can have serious consequences.

As an example a calculation was performed of the impact of climate change on the length of the period of toxic blooms in Puget Sound, an important area of shellfish farming. Results suggested that by year 2100 the period of optimal growth of the toxic dinoflagellate Alexandrium catenella may potentially expand from 68 days to up to 259 days due to warmer water temperatures. This would have severe implications for regional food safety as A. catenella produces paralytic shellfish poisoning. It would totally close the area for shellfish harvesting for most of the year devastating the local economy.

Another example of a dinoflagellate known to generally favour warmer conditions is Gambierdiscus toxicus, one of the species producing ciguatoxin. Increases in ciguatera fish poisoning has been observed with elevated sea surface temperatures. Clinical signs in humans eating fish containing the toxin include gastrointestinal, neurologic, and cardiovascular signs. Gastrointestinal signs include vomiting, diarrhea, abdominal pain and cramps. Neurologic signs include itching, pain, visual blurring, weakness, depression and headache. Cardiovascular signs include arrhythmia, bradycardia, hypotension, and cardiac block.

Cyanobacteria can reproduce quickly in favourable conditions, where there is abundant sunlight, still or slow-flowing water and sufficient levels of nutrients, especially nitrogen and phosphorus. In still conditions, surface water may form a separate warm top layer in which cyanobacteria is able to access sunlight and nutrients. If these combined factors are present for several days, cyanobacteria multiply and form large blooms. The problem seems to be getting worse. Polluted farm runoff continues largely unabated, and the climate crisis is producing warmer weather and water temperatures, along with more rainfall – all conditions that feed the blooms. News reports of blooms in the USA have increased every year since 2010, when there were a total of 71 stories about outbreaks. In 2018 there were 452 reports about harmful outbreaks.

Incomplete understanding

As already mentioned above harmful algal blooms usually increase during the warm summer months. As daily temperatures continue to rise, the number of days ideal for harmful algal growth increases. As the planet’s oceans warm, coastal regions are seeing more and more algal blooms, often worsened by fertilizer and manure that runs off from farms. With toxic algal blooms becoming more potent and lasting longer, scientists are taking a closer look at their links to a changing climate. What was once considered a summertime matter is now being considered a year-round issue.

However, the extent to which regional climate change will influence harmful algal bloom dynamics is uncertain as separating the effects of climate change from natural variability remains a key scientific challenge. Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. Nonetheless there is only basic information to speculate upon in which regions or habitats harmful algae may be the most resilient or susceptible. 

We can continue to test for the presence of toxins in seafood as is currently the practice in many countries. But the potential escalation of outbreaks could easily overwhelm the system. Should we risk it? I for one worry about the future given the current trajectory of global warming.

Mycotoxins in a Changing Climate

Global climate change is an issue we should take very seriously now or it will threaten our future food supply. However, I am writing this in June 2020 in the middle of the coronavirus pandemic that is attracting all the attention. There are so far more than 6 million people affected worldwide and soon more than 400,000 deaths.

Most countries, but not all, have reacted with urgency to the acute situation with people movements severely restricted and huge amounts of money spent to support economies. More than one hundred attempts to develop vaccines agains the COVID-19 disease are under way to prevent future outbreaks.

Willingness to limit climate change lacking

We already have the “vaccines” or knowhow to prevent further escalation of the changing climate. Although climate change in the longer term will threaten food security, that is global access to food, and negatively impact food safety with the potential to cause much more pain and suffering, hunger and deaths, it is not getting the same attention as a novel acute disease.

There are many pathways through which climate related factors may impact food safety including: changes in temperature and precipitation patterns, increased frequency and intensity of extreme weather events, ocean warming, and changes in the transport pathways of complex contaminants.

Food security might be the more serious challenge as sufficient access to nutritious food is already an issue in many parts of the world, but long-term quality of life is also threatened by food contamination. We have already covered accumulation of arsenic as an example of heavy metal increases in food caused by climate change. Here we will cover aflatoxin as an example of an increased threat from a range of mycotoxins as fungal growth is influenced by climate change.

Mycotoxin threat will increase

Mycotoxins are compounds naturally produced by a large variety of fungi (moulds) that can cause acute effects, including death, along with chronic illnesses from long-term exposure, including various forms of cancer. It has been estimated that 25% of the world’s yearly crop production is already contaminated with mycotoxins. Mycotoxins are known to occur more frequently in areas with a hot and humid climate.

Aflatoxins, which have the highest acute and chronic toxicity of all mycotoxins, assume particular importance. Aflatoxin produced by Aspergillus flavus and A. parasiticus is a genotoxic carcinogen, but is also a potent acute toxin, and is widely distributed associated especially with maize, groundnuts, tree nuts, figs, dates and certain oil seeds such as cottonseed.

Aflatoxins are a group of approximately 20 related fungal metabolites. They are heat stable and difficult to destroy during processing. Thus exposure, both acute and chronic, can have significant impacts on vulnerable groups, especially babies and children. Four aflatoxins – B1, B2, G1 and G2 – are particularly dangerous to humans and animals.

Health effects of aflatoxin exposure

Outbreaks of acute aflatoxicosis were reported in Kenya in 2004 with 125 deaths resulting from consumption of aflatoxin contaminated maize with repeated events in 2005 and 2006. Most recently several deaths attributed to aflatoxins were reported during the summer of 2016 in the United Republic of Tanzania.

However, chronic effects are much more common. Hepatocellular carcinoma, or liver cancer, is the third leading cause of cancer deaths worldwide, with prevalence 16-32 times higher in developing countries than in developed countries. Of the 550,000-600,000 new cases worldwide each year, about 25,000-155,000 may be attributable to aflatoxin exposure. Most cases occur in sub-Saharan Africa, Southeast Asia, and China with largely uncontrolled aflatoxin exposure in food.

The geographical areas subject to aflatoxin growth in maize and wheat are expected to change with temperature increases – it is predicted that aflatoxin contamination and the associated food safety issues will become prevalent in Europe with a temperature increase of +2°C.

Changes in contamination patterns

Aflatoxin contamination causes significant loss for farmers, businesses, and consumers of varied susceptible crops. Climate change alters the complex communities of aflatoxin-producing fungi. This includes changes in space, time and in the quantity of aflatoxin-producers. Generally, if the temperature increases in cool or temperate climates, the respective countries may become more susceptible to aflatoxins. However, tropical countries may become too inhospitable for conventional fungal growth and mycotoxin production.

Although some regions can afford to control the environment of storage facilities to minimize post-harvest problems, this happens at high additional cost.

Many industries frequently affected by aflatoxin contamination know from experience and anecdote that fluctuations in climate impact the extent of contamination. Climate influences contamination, in part, by direct effects on the causative fungi. As climate shifts, so do the complex communities of aflatoxin-producing fungi. This includes changes in the quantity of aflatoxin-producers in the environment and alterations to fungal community structure.

Fluctuations in climate also influence predisposition of hosts to contamination by altering crop development and by affecting insects that create wounds on which aflatoxin-producers proliferate. Aflatoxin contamination is prevalent both in warm humid climates and in irrigated hot deserts. In temperate regions, contamination may be severe during drought.

Public health threat

As usual prevention is much better than late action to repair already existing damage. This is especially important in at risk regions such as parts of Africa and Asia where the risks of exposure to mycotoxins may increase under predicted climate change conditions.

The combination of future food scarcity and contamination of a larger part of the food supply has the potential of creating an explosive public health threat.

Global warming and arsenic in rice

In a series of posts we are going to look at the impact of global warming on food production and the potential for an increase in toxic compounds in our normal diet. First off is rice and higher levels of arsenic found in the rice grain when exposed to higher temperatures during cultivation.

Rice is the world’s most important foodstuff providing nutrients and energy to more than one half of the world’s population. Unfortunately, rice can also contain arsenic, which can cause multiple health conditions and diet-related cancers. In an earlier post we described possible chronic health effects of natural levels of arsenic in food and water.

Here we will cover two issues – the influence of higher global temperatures on arsenic levels in rice and types of arsenic compounds formed in soil under different environmental conditions.

Temperature dependence of arsenic accumulation

Arsenic occurs naturally in soil at different levels across the world. When farmers grow crops like rice under flooded conditions, arsenic is drawn out of the soil and into the water. As rice plants extract water through their roots to its leaves, arsenic follows as it mimics other molecules that rice plants preferentially draw out of the soil.

Now researchers at the University of Washington have found that warmer temperatures, at levels expected under most climate change projections, can lead to higher concentrations of arsenic in rice grains at ranges where they begin to have further health concerns. Arsenic concentrations in the grain more than tripled between the low- and high-temperature treatments.

However, the researchers didn’t have the means to check the type of arsenic compounds found.

Some forms of arsenic are more toxic than others.

It is important to know that not all arsenic is the same as arsenic exists in several different forms. Fish and seafood usually contain high levels of arsenic, but most of this is arsenobetaine, an organic form with little toxicity. It is the inorganic arsenic that can be found in water and rice and a range of other food commodities that has been of particular concern.

However, arsenic speciation is not easy to perform, which has created some confusion. Inorganic and methylated oxyarsenic species have been a focus of research, but thioarsenates, in which sulfur takes the place of oxygen, have largely been ignored.

Now University of Bayreuth researchers, together with scientists from Italy and China, have for the first time systematically investigated under which conditions, and to what extent, sulphur-containing arsenic compounds are formed in rice-growing soils. It turns out that the amounts of thioarsenates formed are linked to the pH-values of the soils and other environmental parameters.

Formation of thioarsenates in soil, their uptake in rice plants and their potential risks to human health urgently require further research as at least one organic sulphur-containing arsenic compound discovered in rice fields is already known to be carcinogenic.

A bad situation potentially made even worse

Arsenic is one of WHO’s 10 chemicals of major public health concern and in particular for the millions of people who rely on rice as their staple food. Young children are also at risk if rice-based products make up a large part of their diet.

Global warming has the potential to make a bad situation even worse. With an increase in global temperatures higher levels of arsenic in rice will follow and the composition of the arsenic compounds may change, for better or worse.

So please be careful in contributing to global warming.

Food fraud – milk

Food fraud is nothing new, but the intensity and frequency have been on the rise. From counterfeit extra-virgin olive oil to intentional adulteration of spices and the manufacturing of fake honey, food fraud has been estimated to be a $US40 billion a year industry. In a series of posts we will cover a range of recent issues.

Milk is the third in our series on fraudulent food

Next to prostitution, historians consider counterfeiting the world’s second oldest profession. Similar to fraudulent honey and olive oil, which we covered in previous posts, food fraud involving milk has been around for centuries and is actually to my surprise number one on the list of food tampering issues worldwide, due in particular to current cheating in the developing world.

But the Western world has had its problems too. It was common in the old German Empire to dilute milk by 50 per cent and to restore the original consistency by adding a range of substances like sugar, flour, chalk or gypsum. Spoiled or otherwise contaminated milk was sold without hesitation.

In the mid-19th century, New York’s dairy farmers increased their profits by feeding their cows with cheap waste from distilleries. This resulted in watery and blue-tinted milk that farmers mixed with starch, plaster, chalk and eggs to improve texture and colour, then diluted further with water.

Milk fraud has now spread to the developing world due to an increased demand for milk.

Increased milk consumption

Milk in its natural form has a high food value, since it is comprised of a wide variety of nutrients which are essential for proper growth and maintenance of the human body. In recent decades, there has been an upsurge in milk consumption worldwide, especially in developing countries, and it is now forming a significant part of the diet for a high proportion of the global population.

As a result of the increased demand, some unscrupulous producers are indulging in milk fraud. This malpractice has become a common problem in the developing countries, which might lack strict vigilance by food safety authorities.

One of the oldest and simplest forms of milk fraud is through the addition of variable volumes of water to artificially increase its volume for greater profit. This can substantially decrease the nutritional value of milk, and if the added water is contaminated there is a risk to human health because of potential waterborne diseases. For infants and children this may be a serious concern as they are more vulnerable, at a critical stage of growth and development and are dependent on milk products for supplies of vital nutrients. Babies fed fraudulent milk are at risk of malnutrition and even death.

Adulterants added to milk

Although the vast majority of food fraud incidents do not pose a public health risk, there have been fraud cases that have caused extensive illness. Perhaps the most widely cited, high-profile case involved the addition of melamine to milk-based products to artificially inflate protein values. In 2008, it was reported that melamine-contaminated baby formula had sickened an estimated 300,000 Chinese children with symptoms of irritability, dysuria, urination difficulties, renal colic, hematuria, or kidney stone passage. Hypertension, edema, or oliguria also occurred in more severe cases, killing a reported 6 infants. 

A range of other inferior cheaper materials may be added to diluted milk to increase the thickness and viscosity of the milk, to maintain the composition of fat, carbohydrate, and/or protein and to increase shelf-life. They include reconstituted milk powder, urea, rice flour, salt, starch, glucose, vegetable oil, animal fat, and whey powder, or even more hazardous chemicals including formalin, hydrogen peroxide, caustic soda, and detergents.

Some of these additions have the potential to cause serious health-related problems.

Toxic effects caused by some milk adulterants

The presence of urea in milk may cause severe human health problems such as impaired vision, diarrhea, and malfunctioning of the kidneys. It may also lead to swollen limbs, irregular heartbeat, muscle cramps, chills and shivering fever, and cancers, though these are less likely with the concentrations present in the adulterated milk.

Formalin is highly toxic to humans in small amounts and is classified as a carcinogen. Its ingestion is known to cause irritation, often leading to dry skin, dermatitis, headaches, dizziness, tearing eyes, sneezing and coughing, and even the development of allergic asthma.

Hydrogen peroxide damages the gastrointestinal cells which can lead to gastritis, inflammation of the intestine, and bloody diarrhea.

Detergents have been shown to cause food poisoning and gastrointestinal complications. Some detergents also contain the toxic ingredient dioxane, which is carcinogenic in nature.

Difficult to quantify food fraud

It is not known how widespread milk fraud is as those who commit fraud want to avoid detection and do not necessarily intend to cause physical harm. Thus, most incidents go undetected since they usually do not result in a food safety risk and consumers often do not notice a quality problem.

The full scale of food fraud is not known, as the number of documented incidents may be a small fraction of the true number of incidents. However, some researchers contend that food adulteration is not necessarily more common now, but reputational repercussions are certainly more far-reaching with today’s worldwide media coverage.

Detecting food fraud relies on testing. As new tests are developed we get better at detecting frauds, but the fraudsters will always be looking for new ways to cheat those tests. 

Newer technology will help fight food fraud in the future. These include tracers and edible inks that can be used to tag foods, biomarkers, and DNA fingerprinting. 

While it might seem alarming to hear reports of fake and adulterated foods, this might actually be a good thing, because it means testing and surveillance is working.

Toothpaste danger?

toothbrushingToothpaste has been around for a very long time with historic references as far back as 377 BC. Modern toothpastes are very different though and contain a myriad of ingredients to improve their mechanical properties, appearance, or smell in order to appeal to consumers. Should we be worried?

Two caveats are needed upfront.

First one, please note the question mark in the title. I am not saying that toothpaste is dangerous, just asking the question after some recent experiences.

Second one, although toothpaste is not food, and this blog is about food, you will at least inadvertently swallow some, and some ingredients will easily be absorbed through the lining of the mouth with a 90% efficiency.

So here we go.

The best toothpaste ever

Some years back our brand of toothpaste exclaimed it was clean and fresh. We were quite happy with that, what more could you ask for? But the marketing gurus obviously thought you needed more so changed it to extra clean and fresh. That’s fine too we thought. We don’t mind having extra clean teeth.

Never satisfied the marketing gurus wanted something more so changed to extra clean and lasting fresh. Well, come on now, didn’t the freshness last before? But there’s more, now the toothpaste exclaims it is extremely clean and lasting fresh. This must be the best toothpaste ever. And this is how they describe the effects:

  • This toothpaste doesn’t just freshen your breath, it invigorates it.
  • Thanks to its micro-active foam that leaves you with a pure breath sensation that last and a feeling of clean like no other.

So what is different?

Several warnings

Curious, for once we decided to read the small print on the tube. Upfront there are several warnings:

  • “Do not swallow, be sure to spit out”
  • “Not for use by children 6 years of age and under”
  • “Do not brush more than three times a day”
  • “If irritation occurs discontinue use”

Quite a list of warnings and as it happened one of us had an “irritation” and had to stop using it. The label claimed it could possibly be an allergy to one of the ingredients.

Checking the ingredients

So what is in this toothpaste? Quite a lot as it happens, but at least no sugar it claims upfront. That’s a relief.

First on the list of ingredients is water and not much to say about that.

Second is the sugar substitute sorbitol followed much further down the list by the artificial sweetener sodium saccharin. Of course, even if there is no sugar, a sweet taste is important for palatability. Saccharin has been shown to cause bladder cancer in rats, but through a mechanism that is not available in humans. No harmful effects are expected from those two ingredients although artificial sweeteners like saccharin might influence the gut flora. This is still to be clarified.

Hydrated silica is an odourless, tasteless, white, gelatinous substance, which is chemically inert. As a fine gel it is abrasive and helps to remove plaque. It is generally considered to be safe, although it might wear down the enamel exposing the dentin underneath.

Glycerin is a colourless, odourless, viscous liquid that is sweet-tasting and non-toxic, so no problem there.

Pentasodium triphosphate is produced on a large scale as a component of many domestic and industrial products, particularly detergents. It has very low human toxicity but in volume can have negative environmental effects by supporting algal growth.

PEG-6 (polyethylene glycol) belongs to a group of petroleum-based compounds that are widely used in cosmetics as thickeners, solvents, softeners, and moisture-carriers. In itself not considered toxic although it can inadvertently be contaminated by other toxic compounds depending on the manufacturing process. A minority of people are allergic to PEG compounds.

Alumina or aluminium oxide is primarily used as an abrasive and thickening agent, but also functions as an anti-caking agent and absorbent. It is safe to use for cosmetic purposes. However, it must be noted that aluminum is a neurotoxin.

chemicalsSodium lauryl sulfate is a surfactant responsible for the foaming action of the toothpaste but it also interferes with the functioning of taste buds by breaking up phospholipids on the tongue. As it is further down the ingredient list the amount in the toothpaste should be fairly low but it should be noted that it has been linked to skin irritation and painful canker sores, with research suggesting that the compound should not be used in people with recurring sores. Sodium lauryl sulfate could potentially be contaminated with 1,4 dioxane, a carcinogenic byproduct.

Flavour is not further specified but might be mint as it is common in toothpaste.

Xanthan gum is a common food additive. It is an effective thickening agent and stabiliser to prevent ingredients from separating. It can cause some side effects such as flatulence and bloating in high doses, but the low amount in toothpaste should not be a problem.

Cocamidopropyl betaine is a mixture of closely related organic compounds derived from coconut oil and dimethylaminopropylamine. It is used as a surfactant and foam booster. It can be an irritant particularly if impurities like amidoamine and dimethylaminopropylamine are not tightly controlled.

Sodium citrate possesses a saline, mildly tart flavour. It is commonly used for flavour or as a preservative. The chemical has been verified to be of low concern.

Titanium dioxide is often used as a pigment, brightener, and opacifier, which is an ingredient that makes a formulation more opaque. Although not relevant for toothpaste, if in powder form and inhaled it can possibly cause cancer. However, titanium dioxide in toothpaste may become dangerous when it is nanoparticle size, an issue still to be resolved.

Carrageenan is an extract from a red seaweed commonly known as Irish Moss. It is a native to the British Isles, where it’s been used in traditional cooking for hundreds of years. Some scientists claim that it can cause a range of health effects while others claim it is perfectly safe. Although the jury is still out, amounts in toothpaste is supposedly too low to cause any health effects.

Sodium fluoride is another controversial compound. It can be toxic in high doses but the low doses ingested through toothpaste and fluoridated water can in a worst case situation cause some slight discolouration of children’s teeth. There have only ever been three reported cases of fluoride toxicity associated with the ingestion of fluoride-containing toothpaste. One involved a 45 year old woman with unusual swelling and pain in her fingers. As it happened the woman admitted to the regular ingestion of large amounts of toothpaste, consuming a tube of it every two days because she “liked the taste”. When asked to switch to a non-fluoride form of toothpaste, her  condition subsided.

Zinc chloride polishes the teeth and reduces oral odour by destroying or inhibiting the growth of microorganisms. We need zinc for healthy development, but in high doses it  might cause nausea, vomiting, diarrhea, metallic taste, kidney and stomach damage in some people. Levels in toothpaste are generally considered as safe.

Sodium hydroxide is a good example of a compound that can cause harm in high doses but is completely harmless in a diluted form.

Limonene is a chemical found in the peels of citrus fruits and in other plants. It is used to make medicine and as a flavouring. Limonene is safe in food amounts. It also appears to be safe for most people in medicinal amounts when taken by mouth for up to one year.

CI 74160 Phthalocyanine blue BN is a bright, crystalline, synthetic blue pigment. The compound is non-biodegradable, but not toxic to fish or plants. No specific dangers have been associated with this compound.

CI 74260 Phthalocyanine green G is a synthetic green pigment available in the form of a soft powder. Classified as not expected to be potentially toxic or harmful although one or more animal studies have shown toxic effects at moderate doses.

So what to do


Well I am happily continuing to use the toothpaste but with some reflections each time. I wouldn’t mind if they removed the blue and green colourings. Sure it looks nice with blue and green stripes among the white but is it really necessary. And to the whiter than white from titanium dioxide, do we need the nanoparticles?

I am happy that they have resisted putting triclosan in their toothpaste to stop bacterial growth as the zinc chloride might to the job as efficiently. But I can only hope that they have full control of their chemistry to avoid toxic byproducts being formed.

Regulators in different countries provide some controls for toothpastes but I would be surprised if there were any extensive testing of the product on the market.

On the other hand we only use about 0.3g of toothpaste per brush so exposure to any of the chemicals in the toothpaste is minimal.

Good to know!

Groundbreaking opinion on dioxin toxicity



Curtesy the European Commission

We have previously covered the group of 29 nasty chemicals collectively called dioxins and dioxin-like PCBs because of their similar mode of action.

In brief, they are toxic chemicals that persist in the environment for years and accumulate at low levels in the food chain, usually in the fatty tissues of animals.

However, different interpretations among scientific organisations of their absolute toxicity have led to some confusion.

Harmonisation needed

In an attempt to develop a better understanding of the risks to human and animal health conferred by dioxins and dioxin-like compounds, the European Food Safety Authority initiated a groundbreaking review of the available scientific literature and exposure information. In an exhaustive opinion published in November 2018, EFSA’s Panel on Contaminants in the Food Chain concluded that such environmental pollutants, although only present at low levels in food and feed, pose a considerable health concern.

Accordingly, the Panel set a new tolerable weekly intake (TWI) for dioxins and dioxin-like PCBs in food of 2 picograms per kilogram of body weight, an incredibly low limit reflecting their severe toxicity.

The new TWI is seven-times lower than the previous EU tolerable intake set by the European Commission’s former Scientific Committee on Food in 2001. The change is based on the availability of new epidemiological human and experimental animal data on the toxicity of these substances and more refined modelling techniques for predicting levels in the human body over time.

Current protection not sufficient

eating_meatThe new TWI is protective against effects on semen quality, the most sensitive adverse health effect, as well as a lower sex ratio of sons to daughters, higher levels of thyroid-stimulating hormone in new-borns and developmental enamel defects on teeth.

Worryingly, data from European countries indicate an exceedance of the new tolerable intake level with the main contributors being fatty fish, cheese and livestock meat.

Average and high exposures were, respectively, up to five and 15 times the new TWI in all age groups.

Should you take action?

As there are little or no acute health effects from consuming single foods containing dioxins and dioxin-like PCBs, it’s more a matter of cumulative chronic effects outside the direct control of individual consumers.

Although the presence of these compounds in food and feed has declined in the last 30 years thanks to the efforts of public authorities and industry, a further concerted effort is needed to bring current exposure to safe levels.

Thus, continued vigilance is important, particularly in light of the new proposed TWI. As this is not always the case and testing of food is expensive, some pressure from consumer groups could be beneficial.

Tea in the News

tea jugTea is the second most consumed beverage on earth after water. The daily cup of tea has many positive associations. Winding down (thought to be due to the relaxing presence of the amino acid L-theanine), or winding up (thanks to caffeine’s influence).

Several health benefits have been attributed to tea, especially green tea consumption. There are claims that green tea has the potential to fight cancer and heart disease, that it can lower cholesterol, burn fat, prevent diabetes and stroke, and stave off dementia. Pretty impressive stuff, but probably far from the real truth. Sure the catechins in tea act as free radical scavengers and might prevent DNA damage. However, it is more likely that the theory that drinking green tea is good for memory is true. Researchers have actually shown that epigallocatechin-3 gallate, a key property of green tea, can affect the generation of brain cells, providing benefits for memory and spatial learning.

So should you drink more tea?

Time to be a little careful as recent research has uncovered a connection of a less pleasant kind – the possibility of pesticides and other carcinogenic chemicals in your tea. Independent lab testing in 2018 by CBC News Canada found that many tea brands contain pesticides over levels permitted in that country.

CBC tested 10 samples of black and green teas including Canada’s most popular brands: Lipton, Red Rose, Tetley and Twinings. Other popular brands tested included No Name, Uncle Lee’s Legends of China, King Cole and Signal. Half of the teas tested contained pesticide residues above the allowable limits in Canada. And eight of the 10 brands tested contained multiple chemicals, with one brand containing residues of 22 different pesticides.

In a way this is nothing new. In 2012, Greenpeace found  that every one of 18 tea samples from nine Chinese tea manufacturers contained a mixture of at least three different kinds of pesticides. In total, as many as 29 different pesticides were detected. Six of the samples contained more than 10 different kinds of pesticides. Pesticides banned in China for use on tea plants and tea leaves were found on 12 samples from eight different tea companies.

Indian tea didn’t fare much better. About 94 per cent of 49 Indian tea brands tested by Greenpeace in 2014 contained pesticide residues, and 59 per cent contained at least one pesticide above the Maximum Residue Level (MRL) set by the EU. Similar to the Chinese teas, 68 per cent of the pesticides discovered in the teas weren’t registered for use in tea cultivation.

Recent European Union pesticide report

Tea plantsFew samples were used for the ad hoc testing above, which could have biased the results. A more comprehensive report from the 2016 testing of pesticide residues in food in the European Union was published in 2018 by the European Food Safety Authority. Although pesticide levels exceeding the MRL amounted to only 3.9 per cent in total, for some products, including tea, the levels were much higher. Of 1016 tea samples tested, 36 per cent contained no detectable pesticides at all, while 24 per cent contained pesticide residue levels exceeding the European Union MRL.

Anthraquinone was one of the substances detected in the European testing. In recent years, issues have emerged with regard to the MRL of anthraquinone, which is set at the analytical detection limit of 0.02mg/kg for food, including tea leaves. In many cases, anthraquinone has not even been used as a pesticide on tea plants. The tea becomes contaminated during drying or packaging, or by smoke caused by tea drying.

Should you be worried about pesticides in tea?

The simple answer is not necessarily, but to understand the issue we need to delve a bit deeper into the setting of MRLs.

The MRL is the highest amount of an agricultural or veterinary chemical residue that is legally allowed in a food product. Levels are set based on how much of the chemical is needed to control pests and/or diseases. The product’s chemistry, metabolism, analytical methodology and residue trial data are also assessed.

Limits are set using internationally recognised methods and national scientific data and are well below the level that could pose health and safety risks to consumers. MRLs help enforcement agencies monitor whether an agvet chemical has been used as directed to control pests and diseases in food production.

Unfortunately, allowable maximum residue levels, that fuzzy line of safe use defined by governments, varies greatly from country to country.

Thus, pesticide residues in tea has been a major non-tariff trade barrier affecting tea trade globally as pointed out by the Food and Agriculture Organisation of the United Nations (FAO). The problem was due mostly to certain default MRLs set at analytical detection limits, like for anthraquinone, and not according to agricultural practice or human toxicity.

As a matter of fact the European Union use a default MRL set at the detection limit for at least 6 other pesticides used on tea in some countries.

FAO pointed out that the only way to tackle this problem would be to help fix realistic MRLs which would be acceptable to all stakeholders in order to ensure food safety as well as smooth tea trade globally.

Not sure yet?

Organic tea 2You might question if we really want any toxins in our tea? Well, like any agricultural food product, tea leaves can be contaminated with agri-chemicals that are used to control pests and diseases. This is an irrefutable fact.

The solution? If you’re health conscious and a big tea drinker, paying a bit more for certified organic loose-leaf teas, and infusing it in an old-fashioned pot or stainless steel infuser, would probably be your best bet.

For the rest of us we can be assured that using only 2g of tea leaves for a cup of tea will pose no major health hazard.

Still it would be good if the tea producing countries could get their act together and sharpen their agricultural practices.


Ignoring responsibility at your peril

oil_(Illuminati Owl)

Oils aren’t always what they say (Photo: Illuminati Owl)

The agri-food industry is no innocent bystander. Maximising sales and profit is more important than looking after their customers. They cleverly invent crops tolerant to their own herbicides through genetic engineering so they can sell both seeds and encourage the spread of questionable poisons. They add sugar to many of their products for children so that people will crave sweet foods throughout life. They cheat on extra virgin oil because they can and reap the profit. They replace beef in processed beef products with cheaper horse meat to gain an upper hand. The lists goes on and on.

And rightly the public is upset. This is reflected by the many news items published by the popular press condemning the latest cheat by industry.

But what about consumer responsibility?

Acrylamide is a good example as it is formed during heating of food as we have previously pointed out. Evidence from animal studies have shown that acrylamide and its metabolite glycidamide are genotoxic and carcinogenic: they damage DNA and cause cancer. While evidence from human studies on the impact of acrylamide in the diet is inconclusive, scientists agree that acrylamide in food has the potential to cause cancer in humans as well and it would be prudent to reduce exposure.


Go easy with the toaster (Photo: DonoVan Govan)

Thus, in early 2017, the UK Food Standards Agency issued consumer recommendations on how to minimise the formation of acrylamide during home cooking by avoiding singeing their toast or leaving roast potatoes to char in the oven.

Acrylamide is a natural by-product of heating and has been present in our food since fire started to be used for food preparation. It is formed by a reaction between amino acids and sugars when foods are heated at high temperatures (over 120°C) during frying, roasting or baking. It can thus be found in a wide range of foods including roasted potatoes and root vegetables, chips, crisps, toast, cakes, biscuits, cereals and coffee.

The formation of acrylamide can be reduced by some simple measures as pointed out by the Food Standards Agency. Aim for a golden yellow colour or lighter when frying, baking, toasting or roasting starchy foods like potatoes, root vegetables and bread. Carefully follow cooking instructions on the pack when frying or oven-cooking packaged food products such as chips, roast potatoes and parsnips. Don’t store raw potatoes in the fridge as it may lead to the formation of more free sugars in the potatoes that can increase overall acrylamide levels.

Parts of the popular press objected

All sensible and practical recommendations. You would have thought that the popular press would support such a consumer initiative. But you would be wrong. Rather, parts of the press attacked the Food Standards Agency for being alarmist. Critics of the advice were quick to point out that animal studies linking acrylamide to cancer have used doses far above the average daily consumption in humans so that extrapolating the results is questionable – even assuming the effect is comparable across species.


Acrylamide is a genotoxic carcinogen.

But genotoxic carcinogens don’t follow the minimum threshold concentration rule below which they are not dangerous at all. With chemicals that damage DNA it’s a linear dose response, so even the smallest dose contributes to the risk. There is no threshold dose for the effect. And to add to the problem it is almost impossible to prove in epidemiological studies that acrylamide is a human carcinogen as its presence is too common to find a group that is not exposed at all.

Therefore, the united verdict of organisations like the International Agency for Research on Cancer, the World Health Organisation, the European Food Safety Authority (EFSA) and UK scientific advisory committees is that acrylamide has the potential to cause human cancer by interacting with the genetic material in cells. In 2015, EFSA published their risk assessment of acrylamide in food confirming that acrylamide levels found in food potentially increases the risk of cancer for all age groups. This means that acrylamide might contribute to our lifetime risk of developing cancer; although it is not possible to estimate how big this contribution may be.

Time for action

With that united front I suggest that you better follow the recommendations issued by the UK Food Standards Agency. I know that you feel safer when driving your own car compared to flying, although the probability of an accident is much higher on the road. I know that it is so much easier to blame the food industry for all ills, rather than take some responsibility for your own food handling.

Maybe it’s time for some action!

Smoke might not be so hot


The good news about smoke and fire

We have previously mentioned the potential harmful effects of smoke-induced compounds formed during barbecuing or smoking of food. Now new findings point to a developmental edge for humans.

A genetic mutation may have helped modern humans adapt to smoke exposure from fires. This might have produced an evolutionary advantage over competitors like Neanderthals as modern humans are the only primates that carry this genetic mutation.

No fire without smoke

There is evidence that both humans and Neanderthals used fire. Our ancestors were likely using fire at least a million years ago, and maybe even two million years ago. Fire would have played an important role for cooking, protection and heating. Cooking with fire allowed our ancestors to incorporate a broader range of foods in the diets by softening roots and tubers and help increase the digestibility of other foods. Fire also provided warmth, and has long been used for landscape burning and as part of hunting and gathering.

But no fire without smoke (or is it the opposite?). And smoke-derived toxins like dioxins and polycyclic aromatic hydrocarbons can lead to respiratory infections and, for expectant mothers, exposure to these toxins can increase the chance of low birth weight and infant mortality. Even worse, they can increase the risk of cancer and lead to cell death at high concentrations.

Increased tolerance to smoke-induced toxins


Exclusive mutation that protects humans (Illustration: MagneticHyena)

The mutation may have offered ancient humans a potentially increased tolerance to toxic materials produced by fires. Although you want your body to be able to detoxify the compounds, doing it too rapidly might overload the system and cause cell death. It is all about differences in the aryl hydrocarbon receptor that regulates the body’s response to smoke-derived toxins. The mutation in the receptor is located in the middle of the ligand-binding domain and is found in all present-day humans. Ligands are small molecules that attach to receptor proteins in certain areas in much the same way that keys fit into locks.

By inhaling smoke and eating charcoal-broiled meat Neanderthals were exposed to large amounts of smoke-derived toxins they metabolised too quickly, while humans would exhibit decreased toxicity because they metabolised these compounds more slowly. Thus, our tolerance allowed us to pick up other bad habits like smoking cigarettes.

But remember that the mutation is not giving us a free-out-of-jail card. Although we are at a great advantage compared to Neanderthals, having the mutation made a hundred-fold to as much as a thousand-fold difference, there is still quite a considerable risk remaining. So go easy with the barbecuing and don’t adopt the bad smoking habit.

Lead – up to no good


Lead in petrol an earlier culprit in lead poisoning.

Lead has been used for thousands of years because it is widespread, easy to extract, and easy to work with. It is highly malleable and easily meltable. Equally, lead poisoning has been documented since ancient Rome, ancient Greece and ancient China. It is thus clear that, ingested or inhaled, lead is poisonous to animals and humans. Still we were foolish enough to add it to petrol starting in the 1920s and use lead pigments particularly in white but also in yellow, orange, and red paint to spread its occurrence even further.

We have lived with the consequences ever since. Lead poisoning typically results from ingestion of food or water contaminated with lead, but may also occur after accidental ingestion of contaminated soil, dust, or lead-based paint. It is a neurotoxin that accumulates both in soft tissues and the bones, damaging the nervous system and causing brain disorders. Lead has been shown many times to permanently reduce the cognitive capacity of children at extremely low levels of exposure. Lead exposure in early childhood has also been linked to violent crime.

But there is more

As if that was not enough, new research has shown that early life exposure can alter the composition of the gut microbiota (remember one of my favourite topics), increasing the chances for obesity in adulthood. So far at least in mice. Lead was added to the drinking water of female mice prior to breeding through nursing their young. The lead levels used  were designed to be within past and present human population exposure levels. Thus the lowest dose used of 5 µg/dL is the same as the current US blood lead action level, while the higher dose mirrored exposure levels during the 1960s and 1970s to be able to evaluate both current and historically relevant lead levels.

Once weaned, the offspring were raised to adulthood without additional exposure, and then tested for lead effects acquired from their mothers. The guts of both males and females exposed to lead had all of the similar complexity in microbiota as those not exposed. The differences were in the balance of the different groups of microorganisms. Due to differences in their gut microbiota, adult male mice exposed to lead during gestation and lactation were 11 percent heavier than those not exposed. But not females, although the researchers speculate that females might have shown effects on obesity if they had followed them longer.

Although improving, it is not over yet


Lead exposure linked to obesity in mice.

So now we have obesity added to the long list of potential harm caused by lead contamination. Fortunately, by the mid-1980s, a significant shift in lead end-use patterns had taken place with lead use phased out from petrol in many countries and banned from paint, but still remaining in some grades of aviation fuel, and in some developing countries.

Although the situation has improved, it is not over yet. Lead may be introduced to foods from the use of lead containing pottery or lead crystalware. Another source is water from lead containing pipes. And wild game that has been shot with lead pellets. Not to forget some odd Chinese herbs found to contain high lead levels.

So vigilance is still needed.