For her PhD in the University’s School of Medical Sciences, Katie O’Neill is conducting laboratory studies to see what happens when apparently “safe” levels of the water-borne toxin known as saxitoxin come in contact with model brain cells.
Saxitoxin is more commonly known as a shellfish poison but it is also produced by blue-green algae, which is a major problem for Australia’s sources of freshwater.
To date, no-one has ever died from exposure to freshwater sources of saxitoxin, and there are strict guidelines limiting the toxin to three micrograms per litre (3µg/L) in Australia’s drinking water.
Nevertheless, Ms O’Neill says the potential impact of even these tiny levels of saxitoxin warrant further investigation, and her research so far seems to justify the interest.
“We’ve conducted two main tests of very low levels of saxitoxin and both have had a significant effect,” Ms O’Neill says.
“First, we looked at what would happen if model brain cells were exposed at or below the water drinking level for seven days, and we found noticeable changes to the shape and structure of those cells in our laboratory studies. So the cells were deformed simply from being exposed at these low levels.
“We then used stem cells in the lab to determine if saxitoxin at the Australian Drinking Water Guideline has an adverse effect on their differentiation into brain cells. We saw a significant drop off in both the development of normal brain cell features and structure, and in the genes they expressed.”
Ms O’Neill says this isn’t necessarily cause for alarm, but it does prompt further questions about how saxitoxin could potentially affect humans.
“How much of this toxin is making it into the nervous system through the blood supply? We suspect very little, simply because the concentrations are tiny and saxitoxin is cleared through urine quite quickly. It doesn’t accumulate in the body,” she says.
“What effect could this have on the developing brain of an unborn child? Again, it’s unlikely to have much of an effect, but we believe further investigation of these issues is warranted. Until we have the evidence, we don’t really know. This work could have implications for the future of our drinking water guidelines.”