By 1961, two more countries had developed and successfully tested nuclear weapons. United Kingdom had started its program during the Second World War in close co-operation with the United States, and the first British bomb was tested on October 3, 1952.On February 13, 1960, France followed suit.he five nuclear weapons states United States, Russia (former Soviet Union), United Kingdom, France and China, are the only countries allowed to have nuclear weapons according to the Non-Proliferation Treaty (NPT) from 1970. All members of the United Nations except Israel, India and Pakistan have signed the NPT.
Breathing of contaminated air is the most common way that workplace chemicals enter the body. Some chemicals, when contacted, can pass through the skin into the blood stream. The eyes may also be a route of entry. Usually, however, only very small quantities of chemicals in the workplace enter the body through the eyes.
1 the time-weighted average (TWA) exposure limit-the maximum average concentration of a chemical in air for a normal 8-hour working day and 40-hour week; 2  the short-term exposure limit (STEL) - the maximum average concentration to which workers can be exposed for a short period (usually 15 minutes);he legal basis for the preparation of occupational exposure limits and biological limits in the European Union is contained in Directive 98/24/EC on chemical agents and Directive 2004/37/EC on carcinogens and mutagens.