The Numbering Of Parts

Most people have great difficulty in conceptualising low frequencies and low concentrations. Pesticide concentrations are reported in parts per million (ppm), parts per billion (ppb) and parts per trillion (ppt). One television personality accused an industrial spokesman of releasing effluent with "15 parts per trillion" (his emphasis, implying a very large, rather than a very small concentration).

There are three million New Zealanders, so one part per million is akin to three people in the entire population. One part per million is

By Jay D Mann one centimetre in one kilometre, or one second every 11.5 days. Because modern methods of chemical analysis have become unbelievably sensitive, pesticide residues can be measured at very low concentrations. The method of reporting these concentrations then becomes an exercise in propaganda. The same results can be stated as 0.05 ppm or 50 ppb or even 50,000 ppt.

I cannot conceive of a billion anything, much less a trillion or quadrillion. One part per billion represents one second spread out over 32 years, or one minute in the time since Christ was born. One part per trillion is one second spread out over 30,000 years. And the five parts per quadrillion, mentioned above, is equivalent to one second in six million years!

We've become very fussy about "contamination" of our foodstuffs by chemicals. In the good old days, US regulations accepted no more than seven maggots per tin of cherries. There are still, I think, allowable numbers of insect parts permitted in tropical spices, reflecting the realities of their production. Ergotfree rye is not demanded, just a grain with less than 2% of the alkaloid-rich fungus.

Lifetime Risks

Risks from environmental hazards are also expressed as, for instance, a one-in-a-million lifetime risk of cancer from a particular hazard. That is the value which US

courts have ruled as being so trivial as to be equivalent to zero risk.

A risk of one-in-a-million sounds almost like a real number. But it is a tiny and unimportant risk, almost a synonym for zero. You accumulate one-in-a-million lifetime risks by each of the following actions:

• drinking half a litre of wine O smoking 1.5 cigarettes
• riding a bicycle for ten minutes
• sailing for two hours
• spending an hour in a coal mine
• spending two days in New York City
• living for two months in a brick house
• eating 100 BBQ steaks
• sleeping in a bed or cradle for one year
• breathing for 20 minutes at age 60

This arbitrary target of one-in-a-million is very difficult to reach. For instance, the lifetime risk from eating cabbage-family crops (including cabbage and broccoli) has been estimated to be about 15 in a million.

[But don't stop eating cabbage! Experimental studies have shown that rats deprived of cabbage are more susceptible to cancer than those getting cabbage. The real world doesn't fit the theoretical equations of environmentalists and economists.]

Glyphosate herbicide, feared by some members of the organic farming movement, has a risk of 0.3-in-a-million. Some fungicides have theoretical risks of 500-in-a-million and are at risk of being banned.

A theoretical risk of, say, 15-in-a-million in exchange for the proven health benefits of eating cabbage seems reasonable. But what about a tisk of 500-in-a-million from fungicides? Is it a serious risk? Are there tradeoffs?

These apparent risks from low doses are based on extremely conservative worst-case extrapolations from high-dose experiments, using mathematical equations that do not fit the real biological world of no-effect thresholds. The estimates could be 100,000-fold too high if the mathematical model is wrong, and the actual risk could well be zero. It's completely impossible to explore low-dose results experimentally.

Professional biologists don't set up experiments where one treatment is expected to produce, say, 1,000,001 cancers compared to untreated controls of 1,000,000 cancers. No amount of replication or increase in sample size could ever prove or disprove the hypothesis, so high doses are tested instead.

Extrapolating high-dose results to much lower doses is comparable to studying the effects of intensive high-jump training on athletes' bones by repeatedly throwing volunteers off 30-metre high cliffs several times a day.

There are tradeoffs to fungicide use. It's self-evident that fungicides are employed to control fungi. Fungi are notorious for producing complex chemicals intended to repel or damage potential competitors for foodstuffs — competitors like other fungi, pigs and people.

You're not being fussy when you reject mouldy fruit or vegetables. A number of these fungal chemicals are cancer-producing or liverdamaging. No-one seems to have calculated the lifetime risk factors from these fungal chemicals, compared to the risk from fungicides.

The reasoning seems to be that everything natural is automatically good. We tend to forget wonderful natural phenomena like childbirth fever, goitre, bubonic plague, famine, smallpox and cholera.

Anti-Water League Warning

Mothers, are you giving your families enough protection from the risks of exposure to water? Do your children understand the hazards of puddles? The Anti-Water League is anxious to warn you about that death-causing chemical — water.

We all know that people who fall overboard in the middle of a deep ocean nearly always drown. On the other hand, some people who fall overboard in shallow water survive. Using this data, we can show mathematically that no matter how shallow the depth of water, risk of drowning can never fall to zero, only to a very low likelihood.

There is no safe threshold.

Multiplying these tiny risks by the total population of the world over the next century or two predicts thousands of deaths from puddles. Individuals should show social responsibility by combatting this death causing drownant, water. They should not be deceived into considering insignificant their personal risk from puddles.

Water is also a chemical poison. Consuming as little as 10 litres of water at one time has proven fatal. Remember, we do not fully understand the risks from chronic exposure to small amounts of water. To confirm a calculated risk of one in a million, three million animals would have to be bred and tested. While waiting for the results of these expensive and time-consuming studies, we cannot allow continued exposure to the risk of water. Legislative action is essential, protecting public health until water is proven to be absolutely safe.

The Anti-Water League believes an immediate ban on rainfall is urgently needed, particularly in urban areas. We recognise that it will take years for farmers to be weaned away from their current technological dependence upon rainwater, but the action must start now.

Join the Anti-Water League today and save a life!

Jay Mann is a plant biochemist.