For about a year, an algal bloom in South Australian waters has had devastating effects on marine life. At my local beach, walks were a sad parade of dead sea life.

But what of the health effects of these algal blooms on humans? And what do a class of compounds called brevetoxins have to do with it?

I’m a toxicologist. Here’s what the evidence says.

What are algal blooms?

Algal blooms are a rapid, explosive growth of algae. These blooms are complex and often contain a variety of algal species, some of which produce toxins. The mix of algal species and amount of toxins produced can vary considerably.

A bewildering variety of toxins can cause effects from nausea to liver failure in humans.

Read more: Australia’s algal bloom catastrophe has left more than 87,000 animals dead. What will happen this summer?

How about in South Australia?

For a long time, it was thought the major species in South Australia’s algal bloom was Karenia mikimotoi.

This does not produce toxins but can suffocate fish by the algae (or fragments of the algae) directly damaging their gills.

This species can irritate our skin and eyes. It can also worsen asthma symptoms, possibly by the same........

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