HL Deb 26 November 1996 vol 576 cc10-1WA
The Countess of Mar

asked Her Majesty's Government:

What would be the effect of a deficiency in the P-450 enzymes upon the ability of humans and animals to detoxify organophosphates, and in what proportion of the population is P-450 deficiency known to occur.

Baroness Cumberlege:

It is impossible to generalise about the metabolism of organophosphates (OPs) because the route of metabolism depends upon the structure of the individual OP. P-450 is not a single entity but a family of enzymes, and in respect of the most common half-dozen, an estimated 1-8 per cent. of the population are thought to have a deficiency.

The Countess of Mar

asked Her Majesty's Government:

Whether there has been established any link between a genetic deficiency of methionine in humans and animals and a reduced ability to detoxify organophosphates, and in what proportion of the population is methionine deficiency known to occur; and

What would be the effect of methionine deficiency on the production of taurine and the efficiency of the blood/brain barrier.

Baroness Cumberlege:

There is no evidence of a dietary deficiency of methionine amongst the population in this country, although methionine deficiency is known to occur in some very rare metabolic defects affecting an estimated 1:200,000 births. It is impossible to generalise about the metabolism of organophosphates (OPs) because the route of metabolism depends upon the structure of the individual OP. The Government have not been able to identify any research into the effect of a methionine deficiency on the production of taurine and the efficiency of the blood/brain barrier.

The Countess of Mar

asked Her Majesty's Government:

Whether there is evidence that humans who have a deficiency in pseudocholinesterase (PsChE) have a reduced ability to detoxify organophosphates and what research has been conducted in this field.

Baroness Cumberlege:

The normal function of plasma (pseudo) cholinesterase is not known, but it is hypothesised that the enzyme acts as a scavenger of antiocholinesterase xenobiotics. There are a number of genetic variants, of pseudocholinesterase and a "silent" gene is known, in which no enzyme is produced in the homozygote. Despite this, reports of an association between atypical or absent pseudocholinesterase and heightened susceptibility to anticholinesterases have been rare. The Government are not aware of any research that has been conducted in this field specifically.