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Showing posts with label arsenic. Show all posts
Showing posts with label arsenic. Show all posts

Tuesday, 27 October 2015

Meat and tobacco: the difference between risk and strength of evidence

Comparing smoking to bacon in terms of risk of cancer is extremely misleading, despite the strength of evidence being similar.

Vegetarians are probably breathing a sigh of relief today as headlines are warning us that processed and cured meats cause cancer. But the way this message has been framed in the media is extremely misleading.

Comparing meat to tobacco, as most news organisations who’ve chosen to report this have done, makes it seem like a bacon sandwich might be just as harmful as a cigarette. This is absolutely not the case.

A bacon sandwich

The headlines are referring to the news that the World Health Organisation has classified cured and processed meats (bacon, salami, sausages, ham) as group 1 carcinogens, because there is a causal link between consuming these meats and bowel cancer. This group also includes tobacco, alcohol, arsenic and asbestos, all known to cause certain cancers.

But just because all these things cause cancer, doesn’t mean they’re all as risky as each other. A substance can increase your risk of cancer a small amount, or, like tobacco, a huge amount. Comparing them like for like is just really confusing to anyone trying to work out how to lead a healthy life.

The risk of lung cancer from smoking is extremely high. Of all cases of lung cancer (44,488 new cases in the UK in 2012), evidence suggests that 86% of these are caused by tobacco. And lung cancer isn’t the only type of cancer caused by smoking. CRUK estimate that 19% of all cancers are caused by smoking. Another way of looking at this is that if smoking was completely eliminated, there would be 64,500 fewer cases of cancer in the UK per year.

In contrast, the recent evidence that suggests a causal link between processed meat and bowel cancer estimates that 21% of bowel cancers (which occurs at slightly lower rates than lung cancer – 41,600 new cases in 2011) were caused by eating processed and red meat. If all such meat was eliminated entirely from our diet, they estimate that 8,800 cases of cancer would be prevented in the UK per year.

All this simplistic reporting ignores a variety of other factors – the amount you consume, for example, is likely to affect your risk a great deal. And that’s not to mention addiction – however much you crave a bacon sandwich at times, it doesn’t contain nicotine.

The WHO have deemed the strength of evidence that processed meats cause cancer to be equivalent to that showing that smoking causes cancer. This means that if you eat a lot of red or processed meats you are increasing your risk of cancer. But to compare it to something as lethal as smoking is confusing and dangerous.

For more information visit:-

Friday, 16 January 2015

Arsenic


Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in conjunction with sulphur and metals, and also as a pure elemental crystal. Arsenic is a metalloid. It can exist in various allotropes, although only the grey form has important use in industry.
 
Arsenic atoms can assume several different bonding patterns which are the basis of its allotropes, each of which has a different colour; metallic grey, yellow and black arsenic. Interestingly, using a hammer to bang on arsenide minerals releases a garlic-like odour, which is the result of toxic fumes created by the oxidation of arsenic to arsenic trioxide.

Arsenic is notoriously poisonous to multicellular life, although a few species of bacteria are able to use arsenic compounds as respiratory metabolites. Arsenic contamination of groundwater is a problem that affects millions of people across the world.
Historically, Arsenic was commonly used as a rodent poison in English households, and it was also a convenient murder weapon, particularly amongst the ruling classes as you may have read in various novels and non-fiction books. However, Victorian England used arsenic in a number of ways; it was incorporated into wallpaper to prevent the growth of mould during the dark, damp English winters, it was used as the green colouring in paints, candies and candles, and as a preservative in lace.

The main use of metallic arsenic is for alloying with lead. Lead components in car batteries are strengthened by the presence of a very small percentage of arsenic.

Widespread arsenic contamination of groundwater has led to a massive epidemic of arsenic poisoning in Bangladesh and neighbouring countries. It is estimated that approximately 57 million people in the Bengal basin are drinking groundwater with arsenic concentrations elevated above the World Health Organization's standard of 10 parts per billion (ppb).

More recently arsenic has been in the news for being found in rice.  Rice holds higher levels of arsenic than other grains and acts as one of nature’s “great scavengers of metallic compounds.” Unlike, millet or polenta, rice planted in arsenic-contaminated fields acts as a vacuum for the toxin.

Rice from different countries contain differing levels of arsenic.  It's recommended that rice is washed before cooking and rinsed afterwards to lessen the effects.

Currently, the FDA in America doesn't have safety levels for arsenic in rice. They've cautioned against making state-by-state or country-by country comparisons in Inorganic Arsenic levels for rice, citing the varying factors that can influence arsenic concentrations, such as soil composition, fertilizers, seasonal variability, and water-use practices.


Evidence-based public health advocates also recommend that, given the lack of regulation or labelling for arsenic in the U.S., children should eat no more than 1 to 1.5 servings per week of rice and should not drink rice milk as part of their daily diet before age 5. They also offer recommendations for adults and infants on how to limit arsenic exposure from rice, drinking water, and fruit juice.

A 2014 World Health Organization advisory conference will consider limits of 200–300 ppb for rice.  The proposed new EU recommendations will limit 200 parts of arsenic per billion for adults and just 100 ppb for children and babies.

For more information visit:-
http://en.wikipedia.org/wiki/Arsenic
http://www.theguardian.com/science/punctuated-equilibrium/2011/oct/14/1
https://time.com/3592399/arsenic-rice/
http://www.dailymail.co.uk/news/article-2817542/More-half-rice-products-exceed-new-EU-limits-ARSENIC.html