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Nanotoxikologie (Subject) / Teil 6 (Lesson)

Klausurvorbereitung

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  • What questions have to be answered to define an exposure scenario? Please give 3 examples! - Who is exposed (consumer or worker)? - By what (a cream, a spray or by a meal)? - How (Dermal, oral, inhalative)? - Doing what? - How long can the exposure take (5 min, 6h or life time)?- Information on the product (i.e. conc. of NM, formulation etc.)
  • To measure release of metal NPs often ICP-MS is used. Please briefly explain this technique. NP are ionized in a plasma (ionized argon) at a temperature of 5000°C → ions are conducted from the plasma via sampler and skimmer into the vacuum-system of the MS → the ion beam is separated into isotopes of different masses
  • a) Please explain the difference between “hazard” and “risk”! b) Can you explain the risk and hazard of CNT? a) Hazard:  •A negative health effect that is induced by a biological, chemical or physical agens.  Risk:  •Describes the probability of health impairment  (this is of course related to a certain amount/ dose of a given substance), i.e. obtained by combining information on HAZARD & EXPOSURE b) CMT are very hazardous, but also very stable = low risk
  • Why is it useful in in silico toxicology for the development of a mathematical model to divide the dataset in a training and a validation set? What is the validation set used for? training set: you present your data from your "gold standard" and train your model, by pairing the input with expected output (fitting the model) => the validation set is used to estimate prediction error for model selection
  • The abbreviation QSAR means what? Quantitative Structure Activity Relationships => physikochemical Descriptors needed
  • What is the difference between a NOAEL and a BMDL. Explain advantages & disadvantages of each approach! => Benchmark dose level => uses a low, but measurable change in response Disadvantages:   - more difficult to use (compared to NOAEL approach) - more time consuming Advantages:    - less dependent from the choice of the tested doses - shape of the dose-response curve is taken into consideration - BMD between different studies don’t vary that much
  • What kind of uncertainty factors are used “by default”? •Uncertainties resulting from inter-species variation => Data from animal studies are applied to estimate effects on humans  •Uncertainties resulting from intra-species variation => Different individuals may respond differently
  • A company wants to produce a cosmetic product containing vitamine C encapsulated into micelles (size approx. 50 nm in diameter)? Will this be regarded as a nanomaterial? Explain. it is a nanoproduct, but per definition micelles are not regarded as nanomaterial => the vitamines are not staying in nanoscale
  • The following scenario should be assumed: A company wants to manufacture a cream containing Nano-SiO2. You have the following data: 1)  The cream should contain 10% (w/w) SiO2. 2)  SiO2 NP should have a mean diameter of 25 nm. 3)  You have no data on the uptake through the skin 4)  Assume that 10 g of the cream is used daily 5)  Concerning possible toxicity you have found a NOAEL of 200 mg/kg body weight (for systemic toxicity) a) Perform a risk assessment. What is your conclusion for this product: is it safe or is there a risk? Please explain. Please also explain how this scenario would change when: b) Using different concentration of Nano-SiO2 (e.g. only 0.5% or 1%) c) Having data for skin penetration a) NP are 1-100nm and biopersitent we don't have any data about the systemic uptake => 100% uptake as a precautionary risk assumption 10g of the cream are taken up daily → 10% SiO2 = 1g → NOAEL 200mg/kg BW (animal) => 2mg/kg BW (human) → average human is about 70kg = 140mg/d → a small risk b) the risk would be smaller, due to the lower uptaken amounts of SiO2 c) then a closer risk assumption can be done => would be lower than 100% uptake, so the TDI would be higher
  • a) Please explain how to calculate the ADI of TiO2 with a NOAEL of 200 mg/kg BW! b) Why do we need uncertainty factors? c) Why is the uncertainty factor for worker lower, than for the humans in general? a) NOAEL : 10 = interspecies variability :10 => intraspecies variability so the ADI would be 200mg/kg/100 = 2mg/kg BW b) to account uncertainties respectively to compensate them c) the deviation of age is lower as for the humans in general
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  • a) What is meant by the ALARA principle? As Low As Reasonably Achievable = ALARA principle Goal: minimization of exposure, without having any threshold
  • a) What is the main difference between the regulations of textiles and cosmetics? b) What is the main postulation of the cosmetic regulation? c) Which authority is dealing with cosmetic regulations? a) they're no specific regulations for textiles unllike they're for cosmetics b) they must be biopersistent and insoluble c) scientific committee on consumer safety = SCSS

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