Sunday, January 7, 2018

Wild meat and botulism - update.

As I suggested in the original post, the tests on food and other samples have now shown that the poisoning of the family in New Zealand, apparently caused by Clostridium botulinum, was not caused by botulin toxin. However, no other explanation for the families symptoms is forthcoming. Conspiracy theorists are suggesting the boar had consumed 1080 poison (used for possum control) but there is no evidence for this. Many other toxins could be involved - fungal or plant toxins, or even toxins in spices brought from India by a relative of the family. Chances are we will never discover the cause in this case. However, reading the increasingly confusing reports around the case does raise concerns that more extensive testing was not conducted at the time.

A further possible explanation might be provided by a Massey University PhD student's work.  Hayley Hunt of the Institute of Veterinary, Animal and Biomedical Sciences is investigating a rare disease in hunting dogs called Go Slow. The disease affects the dogs’ ability to walk by altering the mitochondria (energy-producing structures within cells), so that their muscles are no longer able to contract.  She says the likely cause of the disease is dogs eating wild pig meat that has been poisoned when the pig eats particular plants. The identity of the plant and toxin that may be tainting the pig meat is currently unknown and may be difficult to define, as there are so many possibilities.

Raw water: Is it bullshit?

There is a new fad spreading rapidly in the US.  "Raw water" is the latest craze for health fanatics keen to spend serious money.

What is raw water?  Its proponents claim it is water as nature intended it - unfiltered and untreated, containing minerals from the water source and no chlorine.  One raw water company claims that "all other bottled, filtered, tap, and even spring waters are sterilised with ozone gas, irradiated with UV light, and passed through a submicron filter" and that "blasting water with ozone changes its molecular structure".  Clearly, there is some truth in this statement, but also a lot of nonsense.

Some water sources are indeed safe to consume untreated; others may appear to be so, but are not safe.  In August 2016, over 1000 residents of Havelock North in New Zealand became ill after consuming drinking water from two bores operated by the local council.  Investigations showed that the affected residents had been infected by Campylobacter.  This was not the first time that the bore heads had been found to be contaminated.   The outcome of an extensive investigation was that the water in the bore heads was contaminated with water from an adjoining farm pond on land that had been inundated by heavy rains.  The aquifer was not contained and when the pumps were turned on, water from the pond, probably contaminated with sheep faeces, was drawn into the town supply.  Anecdotal evidence says that the level in the pond dropped when the pumps were turned on.  An immediate response was to chlorinate all water supplied in the area, which annoyed some residents, and the two affected bores were closed.  Water was drawn from other bores in the nearby Hastings area and  the supply has been chlorinated.

I am constantly surprised by people who want to turn back the clock to a time when food and water borne diseases were common, before modern scientific and technological advances made our lives much safer.  Campaigning to ban chlorination of town water is one of those issues.  Consumption of raw milk is another one of those desires that can lead to illness.

However, I am also reminded constantly that many rural areas are not serviced by mains water and wastes are treated on site in septic tanks, then discharged to the land.  Our house on our own lifestyle farm collects water from the roof and stores it in 36,000L tanks.  There is no filtration, chemical or UV treatment.  We, like many other rural dwellers, are thereby deliberately exposing ourselves to risk, though there is no alternative other than boiling water or buying bottled water for drinking.  The only thing I can say is that since moving to the farm over 30 years ago, we have never suffered from gastrointestinal illness.

Where does this leave us?  Treated tap water is probably the safest water supply.  Experience shows that rural tank water is usually safe, though it is not sterile; provided that the tanks are protected from contamination by animals or from septic tanks, there is little to fear from drinking it.  The perceived benefits of bottled raw water may be illusory, and the marketing hype criticising filtration and ultraviolet treatment of spring waters is just plain misleading.  Those getting the most benefit from bottled raw water are the suppliers.




Tuesday, December 12, 2017

Wild meat and botulism? Confusion reigns.

Recently in New Zealand, a family became seriously ill after consuming wild boar.  Authorities have said that the meat is suspected of being contaminated with botulin toxin.  Botulin is one of the most toxic substances on the planet.

I am somewhat confused by the reports - botulin toxin is produced by Clostridium botulinum growing in very low oxygen conditions.  The toxin is heat labile, i.e. it is destroyed by heating.  Apparently, the family ate curry made with the meat, and I would have expected the toxin to be destroyed by the cooking.  The family was reported to have collapsed within minutes of consuming the meal.  I'm not going to be dogmatic about this, but the toxin acts by binding to the nerve synapses, preventing release of actyl choline and thus blocking nerve impulse transmission.  Absorption of the toxin in the gut and transport to the synapses normally takes several hours, so the reported immediate collapse of the family is surprising.   As far as I am aware, there is no information on how long the cooked curry was held before consumption.  Spores of C. botulinum are extremely heat resistant, so if the curry were kept warm for a length of time before consumption, the spores could have germinated and produced toxin, though this implies quite a long time between cooking and consumption.

Health authorities have taken samples for testing and these have been sent to Australia - the tests are not simple, and results may not be available for several weeks.  However, the family is recovering in most cases, and anti-toxin has been administered.  Normally, recovery from botulinum intoxication takes weeks or months, not days.

Meanwhile, Ruapehu District Council has issued a warning over the health and safety of hunted and home kill meat.  It is illegal to sell hunted and home killed meat, but it can be shared with family, friends and visitors.  Again, this is confusing - if it can be legally consumed in this way, then there is no safety issue; it's a matter of regulations designed to ensure that meat offered for sale has been properly processed in an approved premises.  Further confusion arises because hunted and home killed meat can be consumed on a marae for traditional activities, but commercial operations on a marae must use commercially processed meat.

It seems to me that the toxicology report must be made available before conclusions can be drawn on the cause of this disaster for the family, and that reporters and regulators should be very careful to get their facts straight before publishing statements that can confuse the public further.

Friday, November 17, 2017

More food scare mongering

I recently read an article in New Zealand Farmer entitled "The stomach-churning truth about what's in synthetic food".  The writer, Jon Morgan was writing an opinion piece and quoted an article by a British food writer, Joanna Blythman.

She had apparently investigated the ingredients in the "Impossible Burger", which has been launched in the US.  The ingredients can be found in many foods already consumed widely in New Zealand and other countries.

She was upset that the major ingredient by weight was water, suggesting that "no quality product uses it as a bulk ingredient".  I had a look in our food cupboard and refrigerator, and found many processed foods with water listed as the main ingredient.  Practically any food manufactured in which powders, such as milk powder, are incorporated will require water to rehydrate the dry ingredients.  (What does she think is the major component of a beef steak cut from a cattle beast?)

She then got stuck into some of the other dry ingredients - textured wheat protein, potato protein and soya protein isolate, claiming that these were produced using high-tech. chemical and physical processes veiled in secrecy.  The konjac and xanthan gums used in food manufacture were described as industrial hydrocolloids, the latter used in oil drilling muds.  In my opinion, this reference is totally irrelevant - there are many materials found in foods that are also used in unrelated industrial processes, such as starch used in paper coating.

The ingredient that caused Joanna the most heartache appeared to be soy leghemoglobin, which is a protein produced in genetically modified Pichia pastoris and which imparts a meat-like flavour profile onto plant-based foods.  I found a number of scientific studies that tested its safety for consumption at up to 0.8% in ground beef analogues.

Overall, I came to the conclusion that this was just another scare mongering beat up of modern food technology.  It is worth noting that Sir Peter Gluckman, the New Zealand Prime Minister's Chief Science Advisor, has stated that synthetic foods will have a major impact in 10 to 15 years, and that great strides are being made in the commercialisation of synthetic milk and meat.

I also tried to find information on Joanna Blythman's qualifications to comment on the safety of foods.  All I can find is that she graduated from City, University of London.  City is focused on business and the professions, so I can only assume that she has no food or science qualifications (if she does have some, then perhaps I am doing her an injustice) but at the moment, it appears that she is yet another journalist who has set up to criticise the food industry.

Sunday, October 8, 2017

Toxic shellfish - again

Once again, the collection of shellfish from a coastal area of New Zealand is subject to a warning from the Ministry for Primary Industries.  This time the affected area is most of the Taranaki coastline.

Tests on shellfish show that levels of Paralytic Shellfish Poisoning (PSP) toxins are above the safe limit of 0.8 mg/kg set by MPI. Unfortunately, the toxins are not destroyed by cooking, so the only advice is not to collect and eat the shellfish.

I have written about PSP before, so, rather than reiterate the warnings and background, here is the link to the earlier post.

Monday, June 19, 2017

Would you eat transgenic food?

Many readers will immediately respond to the title of this post with a resounding "NO".

Don't be so hasty!

Looking close to home, we find that our own bodies contain many foreign genes.  It is estimated that around 8% of the human genome consists of fragments of endogenous retroviruses - about 100,000 of them.  Not all of these fragments are "junk" (a term the popular press is rather keen on).  A number of viral genes have been co-opted for our own purposes, in gene regulation, production of transfer RNA and ribosomal RNA.  One viral gene is critical to the formation of the placenta.  

On this basis, I'm not too surprised to read a piece of research* that shows that some of our vegetable crops are naturally transgenic.  Cultivated sweet potatoes contain the transfer DNA sequences from a bacterium called Agrobacterium.  This genus naturally infects the roots of certain plants, causing a nodule or hairy roots.  This T-DNA is not present in the wild type sweet potatoes, implying that one or more traits carried on this piece of DNA were selected for during the domestication of the sweet potato.

The authors of the paper point out that sweet potatoes have been consumed for millennia, and that this "may change the paradigm governing the “unnatural” status of transgenic crops."

If we look further, in my opinion, it is almost certain that we will find other bacterial or viral genes in our fruits and vegetables.


* The article is technical, but you can find it online

The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop



www.pnas.org/cgi/doi/10.1073/pnas.1419685112 

I originally published this article in 2015 on the NZIFST blogspot:  http://nzifst.blogspot.co.nz

Friday, June 9, 2017

Hand washing is REALLY important

According to a post on Stuff, a worker at a Silver Fern Farms meat plant in New Zealand lost her job for not washing her hands.

At first sight, this may appear to be a draconian decision, but the company had written procedures in place, stating that if a worker touched dropped meat, they should wash their hands before handling other meat being prepared for packaging.  Meat that has fallen onto the floor can be contaminated by many different bacteria and by other organic material.  Handling this fallen meat and the area around the dropped meat table could contaminate the worker's hands and hence other meat being packaged.

If the worker had been properly inducted into the plant, she would have been made aware of the requirement to wash hands after retrieving meat from the floor and transferring it to the dropped meat table.

The real problem is that the company has a meat export licence that almost certainly has stringent hygiene requirements incorporated.  Thus failing to observe the written procedures in relation to dropped meat could have put the licence, and the livelihoods of all other workers at the plant, at risk.