Monocrotophos: A Deadly Insecticide

A recent incident in India has left 23 children dead as a result of cooking oil contaminated with monocrotophos. Being as this was a free meal by government, aimed to keep 120 million children well fed and nourished, this turns some heads.

This molecule has been used as an insecticide, but has since been banned in Canada and the US, along with a number of other countries. They have failed to keep a ban on such pesticides due to the issue of having to feed so many hungry mouths, and needing a high crop output. In the countries where it is still legally used as a pesticide it is required to dilute it to 16% by volume of water. But in this case there was no dilution, indicating that there was direct contact with the poison after the oil processing.

This then becomes a question of who is responsible for insuring this doesn't happen again? One option is to enforce the correct usage and safety for this material, but considering the large illiteracy of the population, and difficulty in setting up an enforcement task, this poses much difficulty.

My opinion in how to prevent something like this from happening again is to enforce limitations on the manufacturer of the insecticide, the ones who enticed the Indian government into lifting the ban with their low price point. To either enforce a ban on synthesizing the compound all together, or to impose a concentration restriction, making the manufacturer dilute before the product is sold

The Chemistry of Cement

Cement, the binder used to hold objects together, most commonly used in concrete and mortar.  The chemistry of cement can be thought of as a deconstruction of a chemical, only to reconstruct the same chemical, but in a different shape. This molecule that we will be looking at is Calcium Carbonate, a component of seashells, and limestone. To start the process of creating cement, the CaCO₃ must be broken down into Calcium oxide through heating it at 825°C, in a process called lime calcination, possessing the equation CaCO₃ → CaO + CO₂. This Calcium oxide exists in a light powdery form, capable of being transported easily to wherever needs to be cemented. Once the cement is ready to be made, the CaO is mixed with water to produce Calcium Hydroxide, Ca(OH)₂, in the equation CaO + H₂O → Ca(OH)₂. This watery paste is ready to be placed into the mould to set. In the setting process, the Calcium Hydroxide returns to it's original state of Calcium Carbonate, through a slow process of combining with the carbon dioxide within the air in the chemical equation Ca(OH)₂ + CO₂ → CaCO₃ + H₂O.

Mushroom Coral as a Sunscreen

In an episode of Man vs. Wild that I was watching, a Mushroom Coral's mucus was used as a sunscreen, so me as a chemist interested in cosmetics, I wanted to know what photoprotecting chemicals were in this mucus.  The coral Fungia fungites and a couple other species gained this ability to protect themselves because they would grow in shallow water of the Adaman Sea where a lot of UV radiation penetrates through the clear water.  First looking at this ability one would expect the coral to synthesize these molecules, but it turns out that the culprits are tiny symbiotic dinoflagellates. In a paper from 1999 by Brown¹ studying the makeup of the mucus required for photoprotection, they look at the concentration of xanthophylls in the mucus, the primary photoprotector. Their study looked at how the concentrations of xanthophylls varried throughout the day, and showed that it is best to harvest the mucus at noon when the xanthophylls are at their peak concentration.

So finally to the chemistry of all of this. The molecule shown above is called diatoxanthin, which is a type of xanthophylls, and this is the molecule mostly responsible for filtering out the harmful rays.  So how does this happen? Well molecules and atoms absorb light one way or another through absorbing the photons, resulting in electron excitation, and in this case, the molecule absorbs in the UV portion of the electromagnetic spectrum. So what happens after the diatoxanthin molecules become excited? Well biology has found a solution for that, which has been named the Xanthophyll Cycle. It's job is to convert all the used up diatoxanthin back into diatoxanthin.

References:
1. Fitt, W. K., R. P. Dunne, S. W. Gibb, D. G. Cummings, I. Ambarsari, B. E. Brown, and M. E. Warner. "Diurnal Changes in Photochemical Efficiency and Xanthophyll Concentrations in Shallow Water Reef Corals : Evidence for Photoinhibition and Photoprotection." Coral Reefs (1999): 99-105.

4-Methylimidizole, a Pepsi Additive

Recently the news has been discussing Pepsi's additive 4-methylimidizole in the caramel colouring of their popular drinks, with the fact that the Centre for Environmental Health has deemed it unsafe. Now should you go into your fridge right now and toss all of your Pepsi into the garbage? No. Although a study that was performed in 2007 gave results showing that 4-methylimidizole has carcinogenic properties in mice and rats, keep in mind that this is at an extremely high dose (115mg/kg of body weight) and the dosage that a normal consumer will receive showed no effects.

So why is this molecule in Pepsi in the first place? It comes with the additive caramel colour, which is produced by a separate manufacturer and is listed as Caramel Colour on the ingredients list.  This molecule is made as a product of the Maillard Reaction, the browning of food, and in this case being the reaction to produce the caramel colour. But the problem with their method in producing the caramel colour is that they use a method with a higher concentration of ammonia, which incidentally ends up producing more 4-methylimidizole than other methods. Since this has come out, the US caramel colour manufacturers have changed their recipe to adhere to the people's reaction, lowering the overall concentration of 4-methylimidizole.  This has yet to change the formulation in other parts of the world though.