Pesticides application and it effects on the environment #2

For every action, there is an equal and opposite reaction.
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I guess we know what that means. Okay ..... for the sake of those who doesn't understand what that means. That's what is known as the third law of new. Am I trying to write about Physics topic..... absolutely CAPITAL NO. I will leave that to the physicist. I want to stay glued to my field. But then why will I use that assertion? Okay ,if you have been following this blog, I have been writing on some chemicals called pesticides for some time now. Many people indiscriminately employed these chemicals to increase agricultural yield, while some merely uses it to control other pest having direct impact on human.

Suffice to know that some of these pest killing chemicals have been banned by various international bodies. European Union countries instituted a ban and completely restricted the application of some of these chemicals because of such effect on bee population. USEPA information on these chemicals can be followed here. Stockholm convention banned on some pesticides can be seen here. Nigeria too, National Agency For Food and Drug Administration and Control (NAFDAC) had also came up with list of several pesticides banned for use in Nigeria. India list of banned pesticides is there in the link too.

Having said it, and with all the effort of government in the world, to ensure that the ecosystem is not pull out of shape as a result of usage of these pests killers, alot are still in the dark as to which and which pesticides to use and not to use.

Even while using moderately permitted ones, people still abuse the permitted ones thereby leading to my first sentence at the beginning of this post "action and reaction are equal and opposite". The pests killers when applied on the surroundings left a marker behind them which now acts back not only on the user, but on several innocent one left in the dark. Though pesticides metabolites have no legs, hand or wings, but they simply move by percolation into the soil, they evaporate or vaporize from hot regions and condense in a cold regions, some left over of these chemicals are also found in agricultural product.

In my previous post, 1, 2, and the most recent, 3 I have been discussing about pesticides and their side effects on human and environment. In the first and second posts, I based it on organochlorines pesticides, but post number 3 is the beginning of Organophosphates. Those pesticides discussed have either been banned completely by some countries just as I have discussed above, or are under strict control. I will therefore pick the boots where I left it so let's continue.

I will start with Parathion methyl:

This compound is part of Organophosphates, and is whitish in appearance. It is solid, but readily solvate in solvent to form a solution. The prepared form for market purpose is light brown in appearance with a pervasive smell (in Xylene). It's solubility is unpredictable in water. It is burnable liquid when present in liquid solvent. Very poisonous compound when breath in, consumed orally or in contact with skin. It has a good insecticidal properties.

Parathion methyl:By Epop - Own work, Public Domain,
In terms of structure as shown above, this compound resemble parathion-ethyl. It's one of the banned insect killer by many nation of the world, while the where it is allowed, it is placed under close watch. The IUPAC named it dimethoxy-(4-nitrophenoxy)-sulfanylidene-phosphane.(I hope that is not difficult for anyone to pronounce.)

Because of its mode of action in the body by repressing the activities of acetylcholinesterase, commonly observed signs of exposure to this compound are;

irritated eyes and skin, nausea and vomiting, abdominal pain, diarrhea, salivation, feeling weak and tired, headache, runny nose, tightness in the chest, blurry vision, pupil constriction, irregular heartbeat, muscle twitches (fasciculation), and difficulty breathing.
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Research conducted recently by a group on this substance, using Sprague-Dawley rats that are pregnant show how this compound can be deleterious to the pregnant rat . Some of the tested pregnant rat died at some time interval. The report also shows various concentration of this compound in different tissue of the female pregnant rat. Including the umbilical cord, such that it penetrates into the foetus. From the report, it may be said that pregnant women and the foetus may be at danger when exposed to this compound. Based on the report, pregnant women should stay away from having direct contact with the compound.

This pesticide because of it restraining effect on the acetylcholinesterase enzyme activities has been placed under Very Hazardous substance by the WHO, thanks to Rotterdam Convention too for labelling it as Severally Hazardous. Because of this, ban is placed on it market transaction over the globe. When allowed to be used by some country , it is under close monitor.

Next on the discussion is Chlorpyrifos:

This compound is also another example of Organophosphates it's physical appearance is colourless and smell like a spoiled egg. It has a molecular formula. C₉H₁₁Cl₃NO₃PS .

Chlorpyrifos:By NEUROtiker (talk) - Own work, Public Domain,
It anhilate insects and leaves no worms behind. It's an effective control measure against pest on farm land and residences. Like every other example, it interaction with nervous system on organisms under attack is by taking preventive activities against enzyme acetylcholinesterase such that the enzyme is render useless.

It's is less hazardous on human according to WHO report. When one is over exposed to it, and amount exposed to is higher than acceptable limits, it can escalate or result to several disorder such as, neurological, body resistance against diseases , and growth.

Pregnant women are strongly advised to keep bay where this compound is use because of it deleterious effect on the mental health of the fetus. Infact, United States as a result of this, ban it's use in most residences in the in 2001.

However, it's still in use for agricultural protection purpose.

The application of this compound involve diluting the concentrate to 0.5% from the real concentrate which could be at 23% and some time at 50%. So at 0.5% it can be applied by spraying over a wide range of land mass.

WHO declared this compound to be mildly dangerous. It's LD₅₀ when ingested by mouth in laboratory animals is said to be from 32-1000 milligram per kilograms.

The LD₅₀ Skin contact and subsequent absorption on laboratory rat is higher than 2000 milligrams per kilogram, while that conducted on rabbits ranges from 1000 - 2000 milligram per kilogram.

Symptoms of severe toxicity is developed when there is an obstruction with the pathway of acetylcholine neurotransmission giving rise to several signs of problem in the neuromuscular.

Though simple symptoms such as water coming out from the eyes, more saliva ,high perspiration and some minor symptoms too could be as a result of little exposure to the compound.

However, the following symptoms could be as a result of lesser interaction with the compound ,like muscle jerk, fatigue,
blunt sight, dysentery. When the dosage leading to poisoning is on the high level, convulsion, immobility, coma, breathlessness because of lung malfunctioning do arise.

The symptoms in children is different in that they may have weaken muscle, and not muscle jerk, more secretions of saliva and not perspiration.

Let's take a quick look at Diazinon:

Diazinon:By Jü - Own work, Public Domain,
It's a colourless liquid, turning dark brown. And smells like ester. It has it's IUPAC name as O,O-Diethyl O-[4-methyl-6-(propan-2-yl)pyrimidin-2-yl] phosphorothioate, INN - Dimpylate),

It is a thiophosphoric acid ester see to kill house hold insects like cockroaches, soldier ants and many more. It is a chemical that can easily be washed off the surface because it is not absorbed into the organisms body.(Nonsystemic).It's house hold use was banned in the United States in the year 2004. Though still in use to control pest on farm land. When ingested, atropine can be use to neutralize it.
The chemical formula for Diazinon is C₁₂H₂₁N₂O₃PS

This compound is known to be highly toxic when taken by backbone animals. The general method of contact is when it is assimilated into the body, though it can be breath in too. The signs observed for poisoning is same also with other chemicals having similar function.

Atropine mentioned here is designed to neutralize poisoning of some pesticides that are refered to as nerve agent, it also reduce amount of saliva formed when surgical procedure is been perform. It can be given intravenously or intramuscularly.

Atropine:By Harbin - Own work, Public Domain,

SUMMARY

Most pest killer chemicals are banned from use by various government all over the world.
Every pest killing chemicals always leaves a trail behind.
When human being is over exposed to these chemicals and amount exposed to is higher than acceptable limits, it can escalate or result to several disorder such as, neurological, body resistance against diseases , and growth.
Special thanks to @alexdory, @greenrun and @gentleshaid for giving insight on how to write equation using Markdown. Am indebted to you all

If you find this post interesting kindly drop your comment behind and let's discuss it. You can join @steemstem on discord by clicking on discord

REFERENCES

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