Friday, August 17, 2007


Economist Walter E Williams is the latest to get the Lambert treatment, Lambert starting off his post by calling Williams a "DDT hoax spreader" for writing:
In Sri Lanka, in 1948, there were 2.8 million malaria cases and 7,300 malaria deaths. With widespread DDT use, malaria cases fell to 17 and no deaths in 1963. After DDT use was discontinued, Sri Lankan malaria cases rose to 2.5 million in the years 1968 and 1969, and the disease remains a killer in Sri Lanka today.
Lambert states that the above excerpt erroneously claims "environmentalist pressure forced Sri Lanka to ban DDT, leading to a resurgence of malaria". In fact, Williams makes no such claim. (I didn't bother to check Williams' numbers because it isn't the numbers Lambert objects to.)

Lambert then questions Williams claim that "volunteers ate 32 ounces of DDT for a year and a half" without suffering adverse effect:
You know, two pounds of DDT is a lot of DDT. It's a bit worrying that Williams felt it plausible that volunteers would chow down on 2 pounds of DDT every day for a year and a half.
It's difficult to work out exactly what Williams was trying to say but it doesn't matter because any way you look at it, he's wrong: the 18 month study involved volunteers ingesting 35 mg of DDT per day.

Regardless, scientist Lambert doesn't put the 35 mg per person per day trial into perspective. The calculated average ingestion of DDT by Americans prior to the 1972 ban was 13.8 μg or .0000138 grams per day. By 1990 average DDT/DDE (a DDT breakdown product) ingestion by Americans was down to 659 ng (.000000659 grams) per day. It should reassure everyone concerned about DDT's possible health effects that volunteers were unaffected by .035 grams of DDT per day with a total exposure over 18 months many times greater than that ingested by the average American over a lifetime.

Lambert doesn't bother explaining any of this because he's out to score political points; not to enlighten. Such is the science of Tim Lambert.

Note: Please feel free to check my calculations above; it's been a long day and I'm not very good at maths even when fully alert.


Post a Comment

<< Home