toxic agents I

Question 1

why study about metal toxicity?

Answer 1

because most objects contain metal and is exposed to it daily. commonly used in industrial process, present in soil (food, drinks, water pipes)

Question 2

where is lead mostly found?

Answer 2

in paints, dyes, ceramic glazed, and water pipes

Question 3

what is lead? how are people exposed to it?

Answer 3

• lead is not biodegradable, and is highly toxic to the environment (will likely stay long)
• people are exposed to hand and mouth transfer of old paint chips (children); through food and water (adult)

Question 4

what is arsenic (inorganic)?

Answer 4

• • is toxic and carcinogenic
• inorganic arsenic are more toxic than organic arsenic
• is more** rapidly absorbed** andrapidly excreted
  route of exposure: dust, skin, drinking water, food, seafood
• ex: sodium arsenate, arsenic acid, arsenic trioxide

Question 5

what are pesticides?

Answer 5

any substance used to prevent, destroy, repel or mitigate pests

Question 6

types of pesticides? (there are 4!)

Answer 6

insecticides, herbicides (weeds and wild plants), fungicides (fungi and molds), rodenticides

Question 7

treatment of pesticides?

Answer 7

atropine (muscarinic receptor antagonist) = block acetylcholine binding
or 2-PAM = dephosphorylate AchE

Question 8

treatment of lead toxicity?

Answer 8

oral chealting agent DMSA (succimer)
- can be used, but cannot reverse adverse effect on learning and behaviour

Question 9

treatment of arsenic poisoning?

Answer 9

acute: oral chelator penicillamine/ succimer
chronic: reduce exposure of arsenic

Question 10

toxicity mechanism of lead?

Answer 10

• activate G protein, cause deactivation of phospholipase C (2nd messenger) -> cause catalyzation of PIP to IP3 and DAG
• IP3 will not release stored Ca2+ but stimulate Pb2+ release to combine with calmodulin instead
• cause phosphorylation of calmodulin dependent protein kinase
• lead to abnormal enzyme activities and gene transcription

Question 11

toxicity mechanism of arsenic?

Answer 11

this will cause carcinogenicity!
oxidative DNA damage:
- can cause chromosome aberration/ interfere the cellular signaling
activation of transcription factors:
- alter the gene expression

Question 12

mechanism of pesticides?

Answer 12

will block the AChE, lead to accumulation of acetylcholine at cholinergic synapses and overstimulate the receptors

Question 13

chronic toxicity symptoms of arsenic?

Answer 13

• diffuse/ spotted hyper pigmentation = can induce skin cancer
• liver injury
• numbness in hands and feet
• weak limbs