Chemical
Chemicals make up everything in the world. But spillages and contamination can make things like foodstuff inedible. We have problems in some areas with higher than normal levels of heavy metals accumulating in the body. Certain types of sea creatures accumulate and concentrate toxins, such as puffer fish and tetrodotoxin that accumulates from them eating certain types of bacteria, Pseudomonas and Actinomyces that they ingest, concentrating it in certain areas of the body as a defence mechanism. Some dolphins have been observed and have knowledge how to ‘nibble’ on creatures like puffer fish to give themelves a ‘drug high,’ so it appears the taking of recreational drugs is not a thing limited to humans, gorging on fermenting apples also being observed in the wild. But biological creatures have a susceptibility to phosphorus based chemicals, the organophosphorus class of chemicals, such as thiophosphonates, a well known ones being VX, Sarin and Novichok nerve agents that are acetylcholinesterase inhibitors that stop the muscles from relaxing, so people drown and constrict to death at the same time. It’s said that stocks have been destroyed, with the US and operation CHASE between 1964-68, Red Hat in 1962-2000 and movements in 1971, with agent Orange and Plutonium at Johnston Atoll, and Russia supposely doing so in 2017 with about 40,000 tonnes, but its very likely that around the world at least twice that is still stored somewhere. So we have tonnes of chemicals stored, keeping them well away from populated areas and dumped all over the world hoping that they will quickly disperse and dilute in areas like seas. But, concentrations like this have a habit of staying in one place, geologic events keeping them preserved, a problem or advantage seen in unusual environments. An example of this can be seen with clathrates, where methane, due to low temperature and high pressure at the bottom of an ocean are protected from evaporation, dissapation and chemical conversions that would normally happen if they were stored anywhere else. On heating or disruption they appear in methane bursts that break out and cause problems on the surface before they are destroyed by the seas processes. You find that stocks of such dumped, lost, or stored now ‘inert’ chemicals are assumed to just disappear and degrade over time, losing their ability to do damage through weathering and dilution, but you have a similar problems to something like the SS Richard Montgomery that broke up and sank in 1944.
The ship sank 76 years ago after unloading over 2/3rds of the 6 tonnes munitions from holds 1 and 2, and has been decaying ever since. The top of the mast to the base of the ship is about 100 feet and the remaining munitions that were mainly unfused aircraft bombs totalling about 1,400 tonnes of TNT in holds 3, 4 & 5. It’s a bit strange as hold 3 broke before unloading and flooded and the three holds total about 40% of the capacity. It sits about 70 feet of water ranging from about 60 to 80 feet. The top of the holds are probably around about 40 feet above the keel and the decks being around 15 feet above that. So the closest is probably within 5 feet at very low tide when it’s most likely to collapse. The welded steel construction means that there is about 4,000 fragmented tonnes of it above the explosives. It’s not exactly the same but consider a 14 pounder cannon has a range of 4.5 miles, but that is using propellant rather than high explosives that have a lot more power. Nobody knows the effect of deterioration but I could image a small bolt making 10 miles if it happens in a worst-case scenario, maybe as far as Eastchurch or Thorpe Bay. If the people in the area were evacuated for the day, and there was a remote controlled explosion at high tide with the blast going downwards from the deck it would probably be a lot safer. 
That said, TNT is normally a very safe compound by itself and hard to detonate, even after many years.
You wouldn’t be able to fire it off by hitting it with a hammer for instance, so if that’s all that was there, then it wouldn’t be a problem. But with large-scale metal collapse there is the possibility of a strong enough shock wave being produced by a sudden crush and compression of material, especially if another type of bomb that was not removed went off or a possibly in a superstructure collapse. In which case it’s likely, one up all up.
You also have to consider that if a chance of explosion is the reason why it’s safer to do nothing or investigate it, then there is a substantial risk of explosion and vital information is missing. If it won’t explode, then there is no explosion risk in investigating it, especially if there is the possibility it can be done remotely.
If you want the scale of the problem, the ship carries an estimated 1,400 tonnes of TNT, the bombs that the Luftwaffe usually dropped were 250kg bombs (5,600 of those), the V2 rockets that hit the UK were 1 tonne in size (1,400 of those), and Little boy that exploded 1/3rd of a mile above Hiroshima was supposed to be equivalent to about 15,300 tonnes of TNT (so Montgomery is 9% of it’s size).
If the reports are to be believed most of the 1,400 tonnes of munitions is unfused sealed TNT bombs. You could hit it with a hammer and it would not go off as the shockwave needed to ignite it wouldn’t be there, so there would be next to no chance of explosion. Even after 75 years it’s still very stable stuff even mixed with sea water. If I suspect what they fail to mention is what is also there that was in hold 3 that broke up. TNT has a power about 20,000 times that of petrol and is toxic to marine life, but only gets dangerous in a combination of sea and sun.
If there’s no chance of explosion it can be safely inspected, if it can’t be safely inspected there’s a chance of explosion. What they are worrying about is a similar thing that happened to a Polish ship Kielce in 1967 that was in much deeper water and had a much smaller cargo, causing an effect that was recorded at 4.5 on the Richter scale 3-4 miles away. There have been two similar events elsewhere in the world that have killed hundreds.
Another little known chemical is ammonium nitrate, commonly stored in large quantities as industrial fertiliser all over the world. The have been a number of disasters with this chemical, being accumulated without people really knowing what they were dealing with. ‘It’s a fertiliser, so is used in farming,’ is the thought. High explosives in any reasonable quantity is the thought of the chemist. Look up Oppau, Texas City, Tianjin and the most recent, Beirut, where it had been accumulated for profit and trade as ‘just another chemical.’ The trouble is, this is just the tip of the iceberg as far as chemicals go, many shipments that are allowed into ports turned away because of ‘this rubbish is not our rubbish, so morally should not come here, while freely and daily allowing ‘bombs’ and ‘environmental disaster risks’ into port.
The levels of mercury that cause little or no effect in humans is said to be equivalent to 1 can of light tuna a day for a 200lb (90.7kg) man.
A small tin that is details weighs about 98g. So, at about 120ppb for light tuna that works out to a recommendation of about 0.1 ppb.
A safe dose equivalent that the health authorities allow for is about 3.3ppm for body weight, so a 100kg person should only take in about 0.033 grams in total of mercury per week or 0.005 grams daily. Pregnant women should only take in about 0.016 grams per week or 0.0024 grams daily.
So, the equivalence is probably somewhere over 33 of such tins a week to take you to the maximum limit.
But is this the true figure for its effect? Mercury can be accumulated, but over a year you probably get the maximum that the body will permit. The factors commonly used are those that cause immediate noticeable effects, not ones that may happen and result over a number of years of exposure, the active levels for this maybe being considerably less. Consider that lead in petrol was used for 80 years, up to about the year 2000 before the statistical evidence showed a provable direct link to problems in children, and evidence on the harmful effects of smoking actively suppressed by tobacco companies who sponsored dubious health studies that minimised the risks.
Light tuna is about 120ppb, multiplication factor 1
Skipjack Tuna is about 145ppb, multiplication factor 1.21
Albacore Tuna is about 350ppb of mercury, multiplication factor 2.92
Frozen Tuna steaks about 384ppb, multiplication factor 3.2
Shrimp about 12ppb, multiplication factor 0.1
Bluefin Tuna sushi about 1000ppb, multiplication factor 8.33
Basically, the bigger the fish, the more mercury it can absorb.
Health authority recommended consumptions include, Deep sea perch or catfish, a maximum of 150 gram serving a week and shark, swordfish and marlin a maximum of 150 gram serving a fortnight.
Cadmium is another accumulative poison that has been found in the environment that a normal person may ingest is about 1 part per million, chronic exposure being around about 25ppm.
Aluminium may also have an adverse effect, being linked to dementia type symptoms when water treatment goes wrong, so there may be a link to actual dementia in its use. Aluminium salts are commonly added at low level to make it ‘sparkling,’ and other chemicals such as orthophosphates, to stop the water eating away lead pipes and added lead overhead to water, many older pipes throughout the world still being constructed of those, lead being likely responsible for irreversible cognitive problems in childhood. This is why lead was removed from most petrol’s.
Some areas have high levels of arsenic in the soils and growing home vegetables is discouraged.
Then we come to things called polyfluoroalkyl substances or PFA’s for short. These are often call ‘forever chemicals’ because of their inability to be broken down in the environment, which may lead to a concentration at some point. The main PFA’s are perfluorohexanesulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluoroheptanoic acid (PFHpA) and perfluorobutanesulfonic acid (PFBS). They are found in non-stick cookware, candy wrappers, water resistant fibres, stain resistant cleaning materials, pizza boxes and cosmetics and balms, and some fire-retardant foams. Teflon is a PFA (PTFE) that has a direct contact with heat and food that was discovered in 1938 and came into widespread use in the 1960’s. In use in other areas since the 1950’s, many people animals and fish have levels of PFA’s in them because of the widespread use, because of their ability not to break down easily, but the concern is that they can break down easily where they shouldn’t and interfere with natural processes in the body. The carbon fluorine bond is one of the strongest in chemistry, but has been linked to all kinds of diseases, such as cancer of the kidneys, testes, thyroid disease, colitis, high cholesterol, colitis, low fertility, poor immune system, interfering with natural hormones, growth, behaviour and learning in infants and children, although no definitive link has ever been proven so far. The idea is that they don’t seem to break down easily, so they must be doing something, not just staying inert. The fact that the lifestyles are pretty poor doesn’t seem to be included in the equation. Eat junk food, high in fat and sugar, alcohol, smoke, drive big cars to school, do little exercise and surround yourself with all kinds of radiations, got to be the semi-inert plastic that does it. I remember an original plan to put plastic in food as a replacement for low fibre content, a sort of polyfilla over the cracks of poor nutrition standards. As for the artificial and chemical conconction of healthy spreads over butter, don’t go there.
A similar chemical is found in nature, trifluoracetic acid (TFA, HOOC-CF3), but is a short chain combination compared to the PFA long chain structure, and it’s likely that many of the PFA’s will break down into this compound eventually.
So, this has led a massive reduction before any of the evidence is in or proven by some government organisations, the limit for perfluorooctanoic acid (PFOA) being re-set at 4 parts per quadrillion from 70 parts per trillion. Due to the prevalence of the compound, virtually all rain water in the world is now over this limit, the average person being over the new limit by about 10,000 times, so humans, animals or fish should be treated as a chemical biohazard under the legislation. It’s best not to approach them without some kind of protective equipment such as a full biohazard suit. As for using a non-stick frying pan, this is definitely out as the inference is that you will be dead within days.
Animals have fairly tolerant systems that allow for all kinds of contaminations, much of the levels of these not overtly contributing to damage or interference, but the modern idealogy of 0% pollution for everything means that lack of exposure may have the effect of not prolonging life, but shortening it, things that would normally tension and stress being removed, allowing for a much lower activity level and protection.
It’s a funny principle, but quite often those with an abject fear of things and avoiding them end up living shorter lives on average, if they can be called lives, the very things they use to prolong their lives, more likely causing the things that end up shortening their lives, and the very laws that are poorly thought out and implemented, ending up in disasters of their own making. Cause and effect, a change in environment changing your evolution, not necessarily for the better.