Enviro Tox Of Hg

Question 1

Natural sources of hg?

Answer 1

Geological deposits–found as HgS ore, also high affinity to coal
Weathering of rock
Volcanic eruptions

Question 2

Anthropogenic sources of Hg?

Answer 2

Fossil fuel combustion for power and heating
Metal production
Gold extraction (small and large scale)
Cement production
Chlor-alkali chemical industry
Waste incineration
Dental amalgam

Question 3

What is the grasshopper effect?

Answer 3

Winds and hot air carry volatile Hg to the poles

Question 4

What is arctic Hg depletion?

Answer 4

Hg 0 and sunlight = Hg2+ –> SRB or IRB convert Hg2+ to methyl mercury

Question 5

Toxicity factors of Hg

Answer 5

Route of exposure
Age–fetus most susceptible
Dose and duration
Health of person

Question 6

What enviro route of exposure is most common in humans?

Answer 6

MeHg via fish–>wide bodily distribution

Question 7

Pharmacokinetics of MeHg?

Answer 7

• reaches bodily equilibrium in 4 days
• distributes to brain, liver, kidneys, fetus, bone marrow, breast milk, peripheral nerves
• transported into brain via LAT1 transporter–MeHg looks like L-Met

Question 8

Current treat,want for MeHg?

Answer 8

Lots of L-met to outcompete entrance into brain

Question 9

MeHg MoA?

Answer 9

Loves thiols--inhibits enzymes
Disregulates glutamate
Depletes anti-ox (loves thiols)
Interacts with Se
Increases ROS

Question 10

Minamata disease, MeHg symptoms

Answer 10

Congential disease!!!

• delayed developmental achievement – speech, motor functions
• -severe cerebral impairment–mental retardation, palsy

Question 11

What were post natal minamTa disease symptoms ?

Answer 11

• parasthesia (mouth, hands, feet)
• sensory, auditory disturbances
• concentric visual field restriction
• tinnitus, deafness
• dysarthria (trouble speaking)
• ataxia, tremors
• death

Question 12

How did floods from hydropower reservoirs enhance methylation of Hg?

Answer 12

• decreased pH
• anoxic waters
• nutrient/Hg influx
• happy bacteria–> SRB IRB thrive in anoxic conditions