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Environment and Brain Student Presentations > Bisphenol, PFAs, and Dyflos > Flashcards

Bisphenol, PFAs, and Dyflos Flashcards

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1
Q

What are bisphenols? (1)

Give an example of a bisphenol. (1)

A

Phenolic organic compounds (benzene with added hydroxyl group)

Bisphenol A (BPA)

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2
Q

What are bisphenols used for? (1)

Give some examples. (3)

A

Used to make plastics and resins

EXAMPLES:

  • water bottles
  • tupperware
  • baby toys
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3
Q

Where are bisphenols found in the environment? (1)

A

Air, water, and soil - due to contamination

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4
Q

Give three occupational exposures of BPA. (3)

A
  • Working in thermal paper factories
  • Synthesising BPA in factories
  • Working as a cashier (receipt paper contains BPA)
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5
Q

Give four food/drink environmental sources of BPA. (4)

A
  • Water (contaminated at source or from water bottle)
  • Canned beef
  • Canned chicken
  • Tupperware (rate of contamination increased when polycarbonate is scratched or discoloured)
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6
Q

Describe a way that foetuses and infants can be exposed to bisphenol. (2)

A

Foetus - through placenta

Infants - through breastmilk

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7
Q

Describe how urinary BPA levels affects risk of death. (1)

A

Higher urinary BPA levels = higher risk of death

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8
Q

Give eight risks to human health of bisphenol exposure. (8)

A
  • Sexual dysfunction
  • Male infertility
  • Neurodevelopmental diseases (including ADHD)
  • Anxiety/depression
  • Early puberty
  • Diabetes
  • Obesity
  • Heart disease
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9
Q

Give the relative half-life and the effects of long term exposure on BPA concentrations in human samples. (2)

A
  • Half-life = 6 hours
  • Long term exposure = steady state BPA concentrations in human samples
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10
Q

What is the LogP of bisphenol? (1)

What does this mean about its ability to accumulate in tissues? (1)

A

LogP=3.4 (lipophilic)

Can accumulate in various tissues

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11
Q

Give four ‘tissues’ that bisphenol can accumulate in. (4)

A
  • Amniotic fluid
  • Breastmilk
  • Infant urine
  • Adult serum
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12
Q

Give three reasons why prenatal exposure to BPA is particularly damaging. (3)

A
  • Immature xenobiotic metabolising system
  • Permeable BBB
  • Easier access to affect neurodevelopment and homeostasis
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13
Q

Give three general mechanisms by which bisphenol can affect the brain. (3)

A
  • Incorporates into cellular membrane
  • Changes structure and fluidity of membrane
  • Mimics hormone (oestrogen) action (binds to ERa and ERb oestrogen receptors)
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14
Q

Give four effects of bisphenol mimicking oestrogen hormone action. (4)

A
  • Inhibits adiponectin secretion from adipocytes
  • Modulation of body weight
  • Increased cell proliferation and migration
  • Can promote growth of oestrogen-dependent breast cancer cells (actions limited by tamoxifen)
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15
Q

Fill the gaps relating to bisphenol’s negative consequences on neurodevelopment. (2)

BPA concentrations in pregnancy are associated with microstructural changes in ………………….. of offspring.

It also affects children’s ability to ……………………………. This is particularly seen in females.

A

white matter tracts

internalise/externalise behaviours

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16
Q

Describe two treatments, and their effects, that may treat bisphenol exposure. (2)

A

Tualang honey (improved oestrous cycle and reduced morphological uterus abnormalities)

Taurine (reduced mitochondrial oxidative stress and improved sperm motility and viability; given before BPA exposure and is dose-dependent)

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17
Q

Describe a biological way that exposure to bisphenol can be mitigated. (2)

Suggest a problem with these methods. (1)

A
  • Oxidoreductases (eg. laccase from fungi and bacteria)
  • Catalyst which purifies water

However, high purification costs

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18
Q

Describe a non-biological way to mitigate bisphenol exposure. (2)

A
  • Adsorption to remove BPA from water
  • Can use activated carbon with surface modifications to increase surface area and porosity
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19
Q

Give four legislative rules surrounding the use of bisphenol. (4)

A
  • Can still be used in food contact materials however leaching limit in place
  • Ban in infant feeding bottles and packaging of baby food
  • Concentration limit for thermal paper (BPS could be a safe alternative to BPA)
  • Leeching limit for toys
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20
Q

Briefly describe two court cases surrounding bisphenol and BPA. (2)

A
  • Legal case to name BPA as ‘very high concern’ for wildlife
  • FDA failed to regulate BPA (currently ongoing court case)
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21
Q

Describe the transgenerational effects seen with BPA. (1)

A

Transgenerational effects on fertilisation and blastocyst formation (male fertility)

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22
Q

BPAF has been suggested as a safe alternative to BPA.

Does the evidence support this being a safe alternative? (2)

A

No - BPAF still reduced viability of stem cells

(More research needed for safer alternatives)

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23
Q

What are fluorine-based PFAs? (2)

A
  • Polyfluoroalkyl substances (fluorine + alkyl groups (CH3))
  • Family of 10,000 synthetic man-made chemicals
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24
Q

Name a subgroup of Fluorine-based PFAs. (1)

A

PTFEs (polytetrafluoroethylene; or Teflon)

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25
Q

Give and describe two biochemical properties of fluorine-based PFAs. (2)

Relating to biodegradability and LogP.

A
  • Forever chemicals as little evidence for biodegradation
  • LogP=1.21 (lipophilic)
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26
Q

Describe the relative stability and toxicity of PTFEs as fluorine-based PFAs. (2)

A

More stable forms of PFAs

Toxic

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27
Q

Give four uses of fluorine-based PFAs and PTFEs. (4)

A
  • Water repellent clothing
  • Firefighting foams
  • Stain resistant fabrics
  • Non-stick pans
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28
Q

Give three environmental sources of fluorine-based PFAs. (3)

A
  • Aerospace, automotive, and constructive industries
  • Consumer waste
  • Industrial processes
29
Q

Give three ‘places’ in the environment that can be contaminated by fluorine-based PFAs. (3)

A
  • Soil
  • Water
  • Air
30
Q

Give three ways that humans can be exposed to PFAs. (3)

A
  • Contaminated food/water (bioaccumulates in meat and fish)
  • Breathing vapours
  • Touching concentrated PFAs in workplace (eg. firefighting)
31
Q

True or false? Explain your answer if necessary. (1)

PFAs present in the blood of 97% of Americans, and men generally have higher serum PFA levels.
There is no significant relationship between age and serum PFA levels.

A

True

32
Q

As well as blood, give two other bodily fluids which may contain fluorine-based PFAs. (2)

A
  • Umbilical cord blood
  • Breastmilk
33
Q

Give two potential risk factors for higher blood fluorine-based PFA levels. (2)

A
  • Geographical location
  • Higher income and education?
34
Q

Give six dangers to human health of fluorine-based PFA exposure. (6)

A
  • Reproductive effects (decreased fertility)
  • Developmental defects in children
  • Increased cancer risk
  • Impaired immune system and vaccine response
  • Interference with hormones
  • Increased cholesterol
35
Q

Describe how fluorine-based PFAs travel in the blood and cross/affect the BBB. (5)

A
  • Binds to albumin in blood
  • Crosses BBB via disassembly of tight junctions or transmembrane transporters
  • Disassembly of tight junctions provokes ROS production and actin filament remodelling
  • Astrocyte hypertrophy (may be a cause or consequence of increased BBB entry)
  • Inhibition of P-gp transporter (which is an efflux transporter on BBB)
36
Q

Give three brain areas where fluorine-based PFAs may accumulate. (3)

A
  • Brainstem (medulla & pons)
  • Hippocampus
  • Hypothalamus
37
Q

Describe how fluorine-based PFAs affect the dopaminergic system. (3)

A
  • Accumulate in brainstem which is rich in DA neurones
  • Reduced TH and neurofilament heavy markers
  • May lead to Parkinson’s disease
38
Q

Describe how fluorine-based PFAs impact gating properties and ion channels in the brain. (4)

A
  • Induce Ca release in neurones (maybe via L-type VGCCs)
  • Calcium signalling pathway disruption
  • Changes neuronal structure, signalling, cell death, and ROS
  • Long-term risks of Alzheimer’s
39
Q

Describe how fluorine-based PFAs are linked to ADHD and behavioural issues. (3)

A
  • Hyperactivity/hypoactivity/locomotor deficits in mice
  • Childhood exposure increases behavioural problems and executive dysfunction
  • ADHD treatment pathway impacted by PFAs
40
Q

This is not a question, but a statement.

A

Fluorine-based PFAs impact OATs and OATPS (which impact renal clearance and reabsorption).

BCRP, MRP1, and MRP4 are also inhibited.

41
Q

What are treatments for fluorine-based PFA exposure targeted at? (1)

A

Removing fluorine-based PFAs and PTFE from water systems

42
Q

Give two ways that fluorine-based PFAs may be removed from water systems. (2)

A
  • Oxidation/reduction to break C-F bond via pseudomonas (PFAs)
  • Remove fluorine using magnesium complex (PTFE)
43
Q

Give three legislations/regulatory methods which aim to reduce fluorine-based PFAs exposure. (3)

A
  • Registration, Evaluation, Authorisation, and Restriction of Chemicals (REACH) regulations proposed to change and include 10,000 PFAs
  • Germany, Denmark, Norway, and Sweden submitted proposal to ban PFAs
  • Some banned in USA
44
Q

Give two future ways that fluorine-based PFA exposure may be mitigated. (2)

Suggest a reason why it is so difficult to mitigate fluorine-based PFA exposure. (1)

A
  • 12 Fluor mop made of fluorine and silica to remove PFAs from ground water
  • Bio-based and fluorine-free alternatives (electrospun; nanofibres; silica-based coatings; short-chain PFAs)

Fluorine-based PFAs may be too important to industry to be completely removed.

45
Q

What are phosphate-based dyflos? (1)

A

Chemical compounds which contain phosphate groups in their molecular structure.

46
Q

Give three general properties of phosphate-based dyflos. (3)

A
  • High thermal stability
  • High solubility
  • Low toxicity
47
Q

Give three general uses for phosphate-based dyflos. (3)

A
  • Plasticiser
  • Flame retardant
  • Agriculture
48
Q

Describe how phosphate-based dyflos are used as a plasticiser. (2)

A
  • Reduce intermolecular forces between polymer chains
  • Enhance flexibility; toughness; and processability of plastics and synthetic materials
49
Q

Describe how phosphate-based dyflos are used as a flame retardant. (4)

A
  • Phosphorous compounds form a protective layer of char
  • Or release phosphorous containing gases
  • These inhibit combustion and spread of flames
  • May be used with textiles; plastics; and foams to improve fire safety
50
Q

Give five ways that phosphate-based dyflos are used in agriculture. (5)

A
  • Flame retardants for agricultural buildings
  • Plasticisers for agricultural products
  • Adjuvants or surfactants in pesticides (however resistance means more required to have effect)
  • Soil conditioners to improve structure, enhance nutrient retention, and promote microbial activity
  • Microbial inhibitors in fertilisers, pesticides, and animal feed additives
51
Q

Give four ways that phosphate-based dyflos can enter the environment. (4)

A
  • Industrial spillage/waste/fumes
  • Agricultural runoff
  • Surface water, soil, and air pollution
  • Contamination of habitats and food chains
52
Q

Give five occupational risks/exposures to phosphate-based dyflos. (5)

A
  • Agricultural workers
  • Chemical manufacturing (pesticides; flame retardants; plasticisers; industrial chemicals)
  • Pest control workers
  • Waste management and recycling
  • Industrial maintenance and cleaning
53
Q

Give nine acute signs/symptoms of phosphate-based dyflos exposure. (9)

A
  • Nausea
  • Vomiting
  • Headache
  • Coma
  • Sweating
  • Muscle cramps and pain
  • Irregular heartbeat
  • Respiratory distress (SOB; chest tightness; respiratory failure; death)
  • Convulsions/seizures
54
Q

Describe how phosphate-based dyflos can cause convulsions/seizures. (1)

A

High doses can cause AChR overexcitation in the brain (this can cause brain damage if left)

55
Q

Give four chronic signs/symptoms/effects of phosphate-based dyflos exposure. (4)

A
  • Neurotoxic effects
  • Reproductive and developmental toxicity
  • Carcinogenicity
  • Adverse impacts on immune and endocrine systems
56
Q

Name and describe the uses of a subgroup of phosphate-based dyflos. (2)

A
  • Organophosphates (phosphate + carbon)
  • Which are used as insecticides, herbicides, fungicides, plasticisers, flame retardants, and nerve agents
57
Q

Some phosphate-based dyflos are organophosphates.

Give a use of organophosphates in medical science and also two uses in neuroscience. (3)

A
  • Have been investigated to treat glaucoma and increased intraocular pressure due to inhibitory effects on AChE
  • AChE inhibitor in neuroscience
  • And also is able to induce delayed peripheral neuropathy
58
Q

Give four ways that humans can be exposed to phosphate-based dyflos. (4)

A
  • Skin (dermal) contact
  • Ingestion (residual amounts on crops; accumulation in food chain)
  • Inhalation of vapours
  • Toxic nerve gas attacks
59
Q

Name the main mechanism by which phosphate-based dyflos have an effect on the nervous system. (1)

A

AChE inhibition

60
Q

Describe how phosphate-based dyflos can inhibit AChE, and the effect of this. (4)

A
  • AChE contains serine within active site
  • Organophosphates bind to serine (irreversible)
  • ACh cannot be broken down in synaptic cleft
  • Permanent muscle contraction
61
Q

Describe the association between phosphate-based dyflos and neurodevelopment. (4)

A
  • Evidence showing that Dyflos affects neurodevelopment in children
  • Cognitive, behavioural, and motor effects shown to occur
  • Prenatal exposure is risk factor for poor neurodevelopment
  • Average decrease in IQ of 7.0 at 7 years old
62
Q

Suggest two possible treatments for phosphate-based dyflos exposure. (2)

A
  • Diazepam
  • Oximes
63
Q

Describe how diazepam may be able to treat phosphate-based dyflos exposure. (1)

A

Treats muscle fasciculations and seizures by acting on GABA-A receptors to enhance inhibition

64
Q

Describe how oximes may be able to treat phosphate-based dyflos exposure. (3)

A
  • Reactivate inhibited AChE
  • Transfers phosphate group on OP-AChE complex to oxime
  • Acts at NMJ to reverse respiratory muscle paralysis
65
Q

Describe the length of treatment and any co-medications which have to be given with oximes to treat phosphate-based dyflos exposure. (2)

Explain your answers. (2)

A

Needs long administration

(OP stored in fat begins to leak throughout the body)

Administered with atropine

(oximes cannot penetrate BBB but atropine can, so required to block actions of ACh in brain)

66
Q

Give three examples of oximes that are used to treat phosphate-based dyflos exposure in different countries. (3)

A

2-PAM Cl

Obidoxime

2-PAM iodide

67
Q

Give a potential way of monitoring the effects of phosphate-based dyflos exposure in an individual. (1)

A

Baseline AChE levels before and after exposure

68
Q

Give two mitigative strategies aimed at reducing phosphate-based dyflos exposure. (2)

A
  • No longer registered as a pesticide in the US
  • Registration; approval; labelling; manufacture in good manufacturing practice facility
69
Q

Give two future interventions which may act to reduce phosphate-based dyflos exposure. (2)

A
  • Development of uncharged oximes and nonoximes which can cross BBB as treatment
  • Genomic sequencing and biotechnology to modify enzymes (enhance substrate binding and catalytic activity)

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