Britain not normally renowned for its stringent environmental controls is the first country in the world to establish a standard for levels of the pollutant benzene, following the recent publication of air quality guidelines.

Benzene, which usually comes from car exhaust fumes, is a proven cause of leukemia.

The guidelines, commissioned by the Department of the Environment, set 5 parts per billion (ppb) as the standard, which is 100 times less than the current occupational exposure standard, and call on the government to work towards 1 ppb.

The World Health Organization's air quality standards state there is no level where benzene is safe. Germany and the Netherlands are currently agreeing their own standards.

Professor Anthony Seaton, chairman of the expert panel which produced the report, said that 5 ppb is not a difficult standard to meet, although the reduction to 1 ppb would require a special effort from government.

Better engine design, catalytic convertors and vapour retrieval systems at petrol stations would all help, but the real answer is to reduce the number of cars on the road.

Safer alternatives to benzene are already being introduced in the US, following pressure from government directives.

Estrogen found in chemicals such as pesticides may be the cause of testicular cancer in men and breast cancer in women, and could be responsible for the reduction in sperm counts around the world.

Several studies have started to link these conditions with pesticides, which have been in widespread use for 50 years.

A study at the Mount Sinai Hospital in New York has produced the strongest evidence yet of a link between pesticides and breast cancer (JNCI 1992; 85: 648-52).

The connection between estrogenic agents and diseases in men isn't proven, although work done at the University of Copenhagen and the Reproductive Biology Unit in Edinburgh suggests that exposure while in the womb to environmental estrogens could be responsible for both testicular cancer and lowered sperm counts. Researchers reckon that sperm counts have fallen by 50 per cent between 1930 and 1990.

High residues of pesticides and preservatives have been discovered in imported oranges and home grown blackcurrants examined, according to the Ministry of Agriculture in the UK. About 90 per cent of the oranges, and four of the seven batches of blackcurrants examined were found to be contaminated.

One consignment of oranges from Turkey was recently refused entry into Britain because of contamination, while 20 pesticides have been discovered in oranges from Argentina, Morocco, Cyprus and Israel.

Banned pesticides have also been discovered on winter lettuces in Britain.