1. Bioaccumulation, PBTs, and SVHCs Day 2.
Adam Peters and Graham Merrington
2017

2. Test principles and interpretation Hypothesis testing
Why bother?
Endpoints
Test principles and interpretation
Hypothesis testing
Regression modelling/curve fitting
Reliability and relevance
2017

3. Why bother? Substances accumulate in parts of the environment
the effects of such accumulation are unpredictable in the long-term
such accumulation is practically difficult to reverse
the intrinsic value of pristine environments should be protected
Stockholm convention on Persistent Organic Pollutants (POPs)
International restrictions on production, use, and emissions
Dirty dozen, inc. DDT, PCB, HCB, etc…
2017

4. Key concerns Accumulation in food chains
Poisoning of humans and top predators from ingesting contaminated food
Screening usually identified from partition coefficient
Log KOW > 3, 4.5, 5, etc. depending on specific criteria
Rarely a concern for biodegradable chemicals
2017

5. Basic Mechanisms
Lipophillic chemicals tend to be retained in fats rather than excreted
Levels of the substance accumulate to higher levels than are in the food during the animals lifetime
Most of the body burden will be transferred when the animal is eaten by a predator
Low levels in plants and vegetation can be accumulated to potentially toxic levels in predators
2017

6. Relevance for Human Food Chains
Man Via the Environment
Exposure of humans due to environmental levels of chemicals
Drinking water
Food sources (esp. meat, fish, dairy products)
Atmospheric deposition of dioxins and PCBs to grasslands used for grazing
Accumulation in cows and transfer into milk
High levels of PCBs in cheese and butter
2017

7. Ecosystem Food Chains Secondary Poisoning
(poisoning by ingesting contaminated food)
Low levels taken up into plants and algae
Accumulated by invertebrate consumers
Further accumulation by secondary consumers
Long food chains in marine systems
Long lifespan of some marine mammals
Very high potential for accumulation to potentially toxic levels in some higher marine predators
2016

8. Persistence
Substances which remain in the environment for a very long time
Usually due to very slow biodegradation
Adverse effects extremely difficult to control
Cessation of emission does not result in any immediate change in environmental concentrations
Pristine environments issue
2016

9. Toxicity Usually indicated by CMR type toxicity
Substances with specific risk phrases
High acute ecotoxicity
Likely to cause poisoning of predators/consumers even at relatively low concentrations
2016

10. PBT Substances Persistent, and (long degradation half-life)
Bioaccumulative, and (accumulates in food-chains)
Toxic (likely to poison consumers)
Combination of properties especially problematic
Particular concern for Arctic top predators
Polar bears, sea birds, marine mammals
Restrictions on marketing and use
REACH authorisations
vPvB
2016

11. Substances of Very High Concern
Substances which exhibit an equivalent level of concern to PBT substances, but which do not meet the PBT criteria
Endocrine disrupting substances
Neurotoxic substances
Other unanticipated adverse effects
Wide dispersive use (in combination with other issues)
2017

12. Summary Bioaccumulation Man via the Environment Secondary Poisoning
Persistence
Toxicity
PBT
SVHC
2017

13. 2016