Pollution and toxicity

Question 1

what’s the deal with pollution? what’s the deal with pollutants?

Answer 1

• pollution is the change in the environment producing a condition that’s harmful to living things
  eg: DDTs was a case of pollution
• pollutants are any substance or material that causes harm to organisms

Question 2

what’s the deal with ppb, ppm, pph, ppt? How’s it calculated?

Answer 2

PPM- Parts per million
PPB- parts per billion
PPH- parts per hundred
PPT- parts per trillion

formula= amount of substance/amount of solution Xbillon/hundred/trillion

Question 3

what’s the deal with toxicity?

Answer 3

the ability of a chemical to cause harm to an organism.

• acute toxicity: serious symptoms after one exposure to the chemical.
  eg: methyl isocyanate
• chronic toxicity: diagnosed when symptoms appear only after the chemical has accumulated to a certain level after many many exposures
  eg: lead

Question 4

What’s the deal with LD50?

Answer 4

stands for Lethal Dose 50. The dose which kills 50% of the population it is applied to. It takes into account the organisms that are more resistant to the chemical’s toxic effects.

Question 5

what’s the deal with clostridium botulinum bacterium?

Answer 5

• “botulism” is a fatal illness mainly linked to preserved foods not exposed enough to high temperatures in the preservation process. “botulinum” came from sausages, and later the bacteria was identified and named clostridium botulinum bacterium.
• These bacterias produce the most toxic chemical known called the botulinum toxin A
• it’s LD50 is 0.00000003(ppm)

Question 6

what are the ways chemicals enter our bodies? What’s the most harmful?

Answer 6

1) ingestion- most likely to cause more harm
2) inhale- most likely to cause more harm
3) skin- contact of skin, less likely because cell walls to prevent chemicals from entering freely

Question 7

What has to happen before a drug/chemical becomes available? Why is it important? Why should we question toxicity values? What’s an example that demonstrates this?

Answer 7

testing to approve of daily use. People find the waiting period unnecessary and inconvenient.
3 reasons why it’s important:
1) the dose depends on different people. Eg: A dose that makes someone fatally ill might only cause slight discomfort in another
2) there are different ways the chemical enters our systems and the toxicity depends on that too
3) we can’t completely rely on published toxicity values for humans because they are based on accidental exposure cases(we don’t test on humans).

we should question the toxicity values because we assume that the way lab animals react to the substance is how humans would react to it.
eg: in the 1950s-1960s- many babies were born with missing limbs or very short limbs. The reason being: thalidomide was advertised as a sleeping pill, and many women used this substance. They later found that in rats, the dose could be as high as 4000 ppm with no ill effects, but in pregnant women, a dose of 0.5ppm would produce babies with missing limbs.

Question 8

Acceptable risk?

Answer 8

a risk we accept as normal

eg: the risk of walking is a sprained ankle yet we still walk

Question 9

EVERY chemical has the potential to be harmful, what does it depend on?

Answer 9

if using the chemical is more beneficial than harmful.

Question 10

what are most toxins made from? what for?

Answer 10

• Some of the deadliest toxins are made from plants and animals. They use it to discourage predators and eliminate competitors.
• Most of the toxins are natural.
• the most dangerous man-made toxin is dioxin( less dangerous than botulinum toxin A)