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If you've ever stared at a lab result that exceeds your NEPM HIL and wondered "okay, but what does this actually mean?". This one's for you.
Gunnar and James sit down with Dr Kylie Dodd, environmental toxicologist and risk assessor at GHD, to get into the science behind the numbers that so many of us lean on without fully understanding where they come from. Kylie has a great way of making this stuff click, and the conversation goes places that are genuinely useful for day-to-day practice.
They get into why Tier 1 screening levels are built to be conservative by design, why an exceedance doesn't automatically mean you need to remediate, and what it looks like to think a bit deeper, what they're calling "Tier 1.5 Risk Assessment — without needing to be a fully-fledged risk assessor yourself.
A big chunk of the conversation is about the practical stuff: how to get more out of your conceptual site model (CSM), how to think about exposure pathways and bioaccessibility, and how realistic site use should dictate the way you interpret results. Some of those small shifts in thinking can make a real difference to the recommendations you're putting forward.
They also get into how risk assessments hold up under regulator scrutiny, when an environmental management plan is actually the right tool, and what data decisions early in a project can save a risk assessor a lot of headaches later.
Fair warning: this episode won't make you a risk assessor. But it might change how you think about what those numbers are really telling you — and what you do next.
Links:
Episode 38 The Bioavailability
Recorded on 12 Feb 2026
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The necessary disclaimer: The views, thoughts, and opinions expressed in this Podcast are the speakers’ own. They do not necessarily represent the views, thoughts, and opinions of 4Pillars Environmental Consulting Pty Ltd or any Client, Supplier or other party related to 4Pillars or the speakers.
(c) Gunnar Haid and James Hammond
