Thursday, August 11, 2005

Heavy metal thunder

My family went through a tragedy 3 years ago, with medical causes. During that time, I spent many long hours in the internets, looking for possible cures or other answers.

During this time I found Medscape. I signed up for, and still receive updates from them, espically re: Oncology, & Neurology.

Here's part of the latest, titled "Low-Level Environmental Lead Exposure and Children's Intellectual Function: An International Pooled Analysis":


Lead is a confirmed neurotoxin, but questions remain about lead-associated intellectual deficits at blood lead levels < 10 µg/dL and whether lower exposures are, for a given change in exposure, associated with greater deficits. The objective of this study was to examine the association of intelligence test scores and blood lead concentration, especially for children who had maximal measured blood lead levels < 10 µg/dL. We examined data collected from 1,333 children who participated in seven international population-based longitudinal cohort studies, followed from birth or infancy until 5-10 years of age. The full-scale IQ score was the primary outcome measure.

. . .

We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 µg/dL is associated with intellectual deficits.

. . .


Before 1970, undue lead exposure was defined by a blood lead level of 60 µg/dL or higher--a level often associated with overt signs or symptoms of lead toxicity, such as abdominal colic, anemia, encephalopathy, and death. Since then, the blood lead concentration for defining undue lead exposure has been reduced: from 60 to 40 µg/dL in 1971, to 30 µg/dL in 1978, and to 25 µg/dL in 1985 (CDC 1991). In 1991, the CDC, and subsequently the WHO (1995), further reduced the blood lead value defining undue lead exposure to 10 µg/dL (CDC 1991). These ongoing reductions in the acceptable levels of children's blood lead were motivated by evidence showing that blood lead concentrations as low as 10 µg/dL were associated with adverse effects, such as lower intelligence (CDC 1991; WHO 1995).

. . .

In this pooled analysis, we found evidence of lead-related intellectual deficits among children who had maximal blood lead levels < 7.5 µg/dL. Indeed, we found no evidence of a threshold. Other studies reported a similar finding, but questions about the relationship at lower levels remained because they involved smaller numbers of children with blood lead < 10 µg/dL or they did not adjust for important covariates (Canfield et al. 2003; Fulton et al. 1987; Lanphear et al. 2000; Schwartz 1994; Schwartz and Otto 1991; Walkowiak et al. 1998). In the pooled analysis, we estimated the blood lead-IQ relationship with data from the 5th to 95th percentile of the concurrent blood lead level at the time of IQ testing, which tends to underestimate the adverse effects of blood lead levels. For the entire pooled data set, the observed decline of 6.2 IQ points (95% CI, 3.8-8.6) for an increase in blood lead levels from < 1 to 10 µg/dL was comparable with the 7.4 IQ decrement for an increase in lifetime mean blood lead levels from < 1 to 10 µg/dL observed in the Rochester Longitudinal Study (Canfield et al. 2003).

Deep, dry, and yes, somewhat boring. But awfully important.

I'm sure you get my points, which are several:

1. Anti-science as a science, (I.D.) is crap.

2. Ignoring the environment is crap.

3. Pollution is crap.

4. Corporate polluters who force the public to clean up their misdeeds are crap.

5. Governments which pass laws in favor of polluters are crap.

6. Governments which pass laws relaxing standards on lead are especially crap. Here, and here.

7. Right wing think tanks that propose relaxing lead standards are crap.