Environmental pollution is responsible for a significant share of violent crime and antisocial behaviour, according to an analysis by Roger Masters of Dartmouth College, New Hampshire. He says metals in, drinki, disrupt the neuro social, economic and psychological factors cannot fully explain why some counties in the US have only 100 violent crimes per 100,000 people each year, while others have over 3,000. He points to experiments on cell cultures which have shown that lead partly incapacitates glial cells, which are responsible for "housekeeping" in the brain, mopping up unwanted chemicals. And in people suffering from calcium deficiency, which afflicts some of the poorest citizens in the US, manganese inhibits the uptake of the neuro-transmitters serotonin and dopamine in parts of the brain. These chemicals are known to con- trol impulsive behaviour (New Scientist, Vol 154, No 2084).