1. REAL CASE: 2 dead from alleged milk tea poisoning. http://news.abs-cbn.com/na
ID: 565379 • Letter: 1
Question
1. REAL CASE:
2 dead from alleged milk tea poisoning.
http://news.abs-cbn.com/nation/metro-manila/04/10/15/2-dead-alleged-milk-tea-poisoning
Review this incident.
Determine the hazard characteristics of oxalic acid.
Attach a copy of an MSDS for oxalic acid.
What was the pathway of exposure?
What are the target organ(s) in this case?
What was the root cause of this event?
2.REAL CASE:
Two explosions occurred at a petrochemical plant. One explosion occurred in 1987 and the other in 2002.
The explosions resulted in an estimated 34 tons of chemical residues being released and absorbed into the ground and polluted the ground water. The contaminated ground water was the sole source for the local water supply and provided water to 2.4 million people. The chemicals included benzene, TCE, and PCB.
Discuss the steps that you would take to conduct a risk assessment of this situation.
What information would you need to conduct this risk assessment and how would you obtain it?
3.
A tank farm at a local chemical distribution facility is leaking and is contaminating the groundwater, causing a concentration directly beneath the site of 15.0 milligrams per liter (mg/L). The groundwater is flowing at the rate of 0.20 meters per day toward a public drinking water well one kilometer away. Preliminary measurements indicate that the chemical is subject to degradation in the aquifer with a half -life of 10 years. To be conservative, assume the pollutant does not disperse within the aquifer, but merely flows along with it. The public well pumps 100,000 gallons of water per day, delivered to 50,000 customers.
Estimate the steady-state pollutant concentration expected at the well.
Explanation / Answer
1. Hazard characteristics of oxalic acid:
(i) If oxalic acid is exposed to eyes, it will cause eye burns. This may result in corneal injury.
(ii) If oxalic acid is exposed to skin, it will cause severe skin irritation, and may cause hypocalcemia. Gangrene has occurred in the hands of people working with oxalic acid solutions without rubber gloves. The skin lesions are characterized by cracking of the skin and the development of slow-healing ulcers. The skin may be bluish in color, and the nails brittle and yellow.
(iii) If you inhale oxalic acid vapors, it will cause irritation of the respiratory tract, protein in the urine, nosebleed, ulceration of the mucous membranes, headache, nervousness, cough, vomiting, emaciation, back pain (due to kidney injury), and weakness.
Pathway of exposure: The conjugate base of oxalic acid (H2C2O4) is the hydrogen oxalate (HC2O4-) ion, and its conjugate base (oxalate, i.e. C2O42-) is a competitive inhibitor of the lactate dehydrogenase (LDH) enzyme. LDH catalyzes the conversion of pyruvate to lactic acid (the end product of the fermentation/anaerobic process) oxidizing the coenzyme NADH to NAD+ and H+ concurrently. Restoring NAD+ levels is essential to the continuation of anaerobic energy metabolism through glycolysis. Otherwise, it leads to death.
The target organs, in the given case, are kidneys and brain.
The root cause is the contamination of milk tea by oxalic acid, which causes kidney damage.
You can go through the following link for MSDS in case of any further doubts.
https://uwaterloo.ca/giga-to-nanoelectronics-centre/sites/ca.giga-to-nanoelectronics-centre/files/uploads/files/oxalicacid_0.pdf
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