This ABC news item caught my eye.

NSW HEALTH DENIES BIRTH DEFECT CLUSTER

http://www.abc.net.au/news/stories/2011/05/14/3216913.htm?site=newcastle

In simple terms:

The global incidence of gastroschisis is one in 5,000 live births. In a three year period seven babies with this rare disease were born in the Northern Rivers region of NSW. This works out to an incidence of one in 950.

What are the odds of this happening by chance alone?

It works out to around 1 in 3000. The odds against are 3000 to 1!

Yet Mr. Corben, the region’s public health director says "What we're seeing here is most likely just a random event,"

Is Mr. Corben correct? Is there nothing to worry about?

The numbers quoted in the article suggest 6,650 births in the region in the past 3 years. (7X950).

Let’s look at it from another perspective.

Roughly 396 million babies were born on planet Earth in that period. Let’s divide the Earth in 59,548 “cells” such that in each cell 6,650 babies were born in the past three years. 59,548 X 6,650 gives roughly 396 million births so, by doing this we’ve accounted for all births on the planet.

Let’s also assume that the incidence of gastroschisis is indeed one in 5000 and that the occurrences are completely uncorrelated.

How many cells would you expect to find with at least 7 cases?

It turns out that the number is about 19. You would expect to find 19 little communities (out of 59,548) that recorded 7 or more cases of gastroschisis. From this perspective it looks as if the people in the Northern River region were just among the unlucky few.

Look at it this way. If you buy a lottery ticket the chances of winning a big prize are small. But often somebody does win. They’re lucky.

So you could say the people of the Northern Rivers region won a “negative lottery.” They were among those that got the booby prize.

And then again, maybe there really is some problem in the region.

A case of lies, damned lies and statistics? What, if anything, should Mr. Corben do?

The statistics certainly demand some sort of investigation particularly into the use of the herbicide Atrazine in that area.

Similar events have met with the same response, such as in relation to side effects experienced by those living near macadamia plantations, aerial spraying of banana (and other) crops with dangerous overspray into water catchments; and cancer clusters in St Helens Tasmania, still left unexplained.

Knee-jerk denialism every time but perhaps the attention given to the birth defects may prompt wider scrutiny and investigation.

For what it's worth Pelican, I also think there needs to be further investigation. However I'm not sure it can be done simply by looking at the Northern Rivers Region.

You might need a global investigation. Look for patterns in the occurrence of gastroschisis and see what, if anything, regions that show high or low occurrence have in common.

And then we also have to be open to the possibility that Northern Rivers Region simply drew one of the short straws. It's possible.

However it will be interesting to see if a relatively high rate of this terrible condition persists in the Northern Rivers Region. The longer the region has above average occurrences of gastroschisis the less likely it is that this is down to pure bad luck.

And then there's always the problem that this is a rate disease and resources are limited.

Dear Steven,

Things don't just happen for no reason. The statistics here are worrying and demand a thorough investigation. The incidents of gastroschisis are not only confined to the NSW Norther Rivers region but an alarming number of cases have also been reported in Bunbury WA.
The Health Department (the same as NSW) denies that there is any need for concern. However, how can anyone choose to ignore the stats. In WA the cases have more than doubled since 1980. There were 37 cases recorded between 1980 - 1989. And 99 cases were recorded between 2000 - 2009. Health experts are claiming a link between the birth defects and the use of agricultural chemicals. The Health Departments
(for whatever reason) are choosing to ignore the matter. This must be questioned.

It is cetainly possible steven. There may even be common demographic factors which contribute such as low maternity age, drug use etal that need to be tested.

It would be worth looking at similar incidences elsewhere as you aruge, identifying common factors even where Atrazine is used and not having the same cluster effect (should it even be Atrazine).

Certainly commonalities need to be identified and various factors considered without a pre-determined mindset.

The goal should be that investigations into these cluster occurrences not be shelved as in the too hard basket.

Lexi wrote:

>>In WA the cases have more than doubled since 1980. There were 37 cases recorded between 1980 - 1989. And 99 cases were recorded between 2000 - 2009.>>

I assume that the number of births in WA did not grow as fast as the number of cases of gastroschisis?

If that is the case it indicates an increasing incidence of gastroschisis over a long period. This is a worrying trend and speaks against mere chance and luck of the draw.

>>Health experts are claiming a link between the birth defects and the use of agricultural chemicals.>>

Perhaps. But always remember that correlation is not causation. At one time it appeared that BSE might be linked to the use of certain agricultural chemicals. We now know this is not the case.

>>The Health Departments (for whatever reason) are choosing to ignore the matter. This must be questioned.>>

Agreed. But I doubt the NSW or WA health departments have the capacity to carry out the required investigation. Truth to tell I question whether Australia on its own has the capacity.