Issues With Toxicology

SUBJECT NAME : ISSUES WITH TOXICOLOGY
            SUBJECT CODE  :DNEH1342

Toxicology

Overlapping,discipline with chemistry,biology,medicine and pharmacology, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating exposures to toxins and toxicants.

Issues With Toxicology

Kyshtym  Disaster

The Kyshtym Disaster was a radioactive contamination accident that occurred on 29 September 1957 at Mayak, a plutonium production site in Russia for nuclear weapons and nuclear fuel reprocessing plant of the Soviet Union. 

It measured as a Level 6 disaster on the International Nuclear Event Scale (INES),making it the third-most serious nuclear accident ever recorded, behind the Fukushima Daiichi nuclear disaster and the Chernobyl disaster (both Level 7 on the INES). The event occurred in Ozyorsk, Chelyabinsk Oblast, a closed city built around the Mayak plant, and spread hot particles over more than 20,000 square miles (52,000 km2), where at least 270,000 people lived.

Map of the East Urals Radioactive Trace (EURT): area contaminated by the Kyshtym disaster

Since Ozyorsk/Mayak (named Chelyabinsk-40, then Chelyabinsk-65, until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town.

Kyshtym Disaster Caused by

• Kyshtym disaster was a consequence of the failure to repair a malfunctioning cooling system in a buried tank where liquid reactor waste was stored. 

• For more than a year the tank’s contents grew steadily hotter from radioactive decay, reaching a temperature of about 660 °F (350 °C) by September 29, 1957, when the tank exploded with a force equivalent to at least 70 tons of TNT. 

• The nonnuclear explosion blew off the tank’s one-metre-thick concrete lid and sent a plume of radioactive fallout, including large quantities of long-lasting cesium-137 and strontium-90, into the air. 

• About two-fifths as much radioactivity was released at Kyshtym as was later released at Chernobyl. 

• The plume drifted hundreds of miles, generally northeast, through a region that had hundreds of thousands of inhabitants, but authorities were slow to order evacuation.

Effects on the Population

Because of the accident, food intervention limits regarding the content of radionuclides in food was implemented to protect the public from dangerous radiation exposure. Milk existed as a primary source of contamination of the human diet, comprising up to 50% of ingested radioactivity.

Reference

https://en.wikipedia.org/wiki/Toxicology

https://en.m.wikipedia.org/wiki/Kyshtym_disaster

http://www.environmentandsociety.org/arcadia/nuclear-disaster-kyshtym-1957-and-politics-cold-war

https://www.britannica.com/event/Kyshtym-disaster

http://large.stanford.edu/courses/2015/ph241/chang2/

Bhopal Tragedy

What is Bhopal Gas Tragedy?

• The Bhopal Gas Tragedy (commonly referred to as Bhopal disaster) was a gas leak incident in India, considered one of the world's worst industrial catastrophes.

• It occurred on the night of 2nd-3rd December 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh.

• A leak of methyl isocyanate (MIC) gas and other chemicals from the plant resulted in the exposure of hundreds of thousands of people. 

After effects of Bhopal Tragedy

Though the Bhopal gas tragedy took place close to 29 years ago, the city is still experiencing the effects of the gas leak. Around 3700 people died almost immediately following the incident in December 1984. The immediate cause of death was due to choking, circulatory collapse and pulmonary oedema (filling up of fluid in the lungs). Further post mortem reports revealed that people died not only of suffocation but also because the toxins had caused swelling in the brain, leading to disorientation and finally death, due to collapse of the nervous system. Other conditions include degeneration of the liver, and kidneys and rotting of the intestines. The stillbirth rate was 300% and neonatal mortality (death as an infant) was about 200% right after the tragedy.

Since then clinical studies have shown that the survivors have still been suffering from debilitating conditions such as pulmonary fibrosis, bronchial asthma, chronic obstructive pulmonary disease (COPD), emphysema, recurrent chest infections, keratopathy and corneal opacities. They also showed that the following generations were suffering from respiratory, neurologic, psychiatric and ophthalmic symptoms.

Years later, the effects of the gas leak are still seen, the year 2002 a report published by the Fact-Finding Mission on Bhopal found a number of toxins, including mercury, lead, trichlorobenzene, dichloromethane and chloroform in the breast milk of nursing mothers.

Studies have found that exposure to methyl isocyanate leads to toxicity of the immune system, and alters the DNA of a person, leading to chromosomal instability. Babies born to pregnant woman exposed to MIC in the first trimester of pregnancy, showed symptoms of persistent immune system hyper-responsiveness (responses that are not in line with the amount of irritant present) .There has been a drastic increase in the number of babies born with physical as well as mental deformities. Children are born without arms or legs and are often unable to speak or care for themselves. 

Reference

https://en.m.wikipedia.org/wiki/Bhopal-disaster

https://www.britannica.com/event/Bhopal-disaster

https://www.quora.com/What-were-the-after-effects-of-Bhopal-gas-tragedy

http://www.nbcnews.com/id/37551856/ns/world_news-south_and_central_asia/t/guilty-bhopal-tragedy-killed/#.XHTmjqIzbIU

The Gulf of Mexico Dead Zone

Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water.

An oxygen-starved hypoxic zone – commonly called a dead zone – shown in red, forms each summer in the Gulf of Mexico. Fish and shellfish either leave the oxygen-depleted waters or die, resulting in losses to commercial and sports fisheries. Image via NOAA

Dead Zone caused

The dead zone is caused by nutrient enrichment from the Mississippi River, particularly nitrogen and phosphorous. Watersheds within the Mississippi River Basin drain much of the United States, from Montana to Pennsylvania and extending southward along the Mississippi River. 

Most of the nitrogen input comes from major farming states in the Mississippi River Valley, including Minnesota, Iowa, Illinois, Wisconsin, Missouri, Tennessee, Arkansas, Mississippi, and Louisiana. Nitrogen and phosphorous enter the river through upstream runoff of fertilizers, soil erosion, animal wastes, and sewage. In a natural system, these nutrients aren't significant factors in algae growth because they are depleted in the soil by plants.

However, with anthropogenically increased nitrogen and phosphorus input, algae growth is no longer limited. 

Consequently, algal blooms develop, the food chain is altered, and dissolved oxygen in the area is depleted. The size of the dead zone fluctuates seasonally, as it is exacerbated by farming practices. It is also affected by weather events such as flooding and hurricanes.

WHAT IS BEING DONE ABOUT THE DEAD ZONE?

• The Conservancy is working with farmers to promote more effective and efficient use of fertilizers

• The reconnection of rivers to their floodplains not only helps to mitigate floods, but filter excess nutrients from the water
• Legislation like the RESTORE Act and Farm Bill plays critical role in protecting the country's natural resources.

It's time for us to take a fresh look at the way we manage large rivers and the gulfs and bays into which they flow. We've seen that dams and levees alone will not solve problems like floods and their impact in the Gulf. By managing nutrients more efficiently in farm fields and by restoring wetlands and riparian systems to capture nutrients and reduce runoff, the Conservancy'sMississippi River Program and Gulf of Mexico Initiative are working with farmers and other partners to slow or even reduce the growth of the Gulf’s dead zone and its effects throughout the region.

Reference

https://en.wikipedia.org/wiki/Dead_zone_(ecology)

https://serc.carleton.edu/microbelife/topics/deadzone/index.html

https://earthsky.org/earth/gulf-of-mexico-2018-dead-zone-forecast

https://www.google.com/search?q=gulf+of+mexico+dead+zone&rlz=1C1CHBF_enMY787MY801&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi9-4aBp9ngAhUBo48KHfRoAdkQ_AUIDigB&biw=1093&bih=461#imgrc=zhuLyG3giumj2M