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

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

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

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

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

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

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

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

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

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

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

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

2016