The earliest warnings of the hazards of silica dust
emerged in the 1970s and 1980s, but they were not common until the 1990s.
HONG KONG--One thousand fifty-six patients who received long-term exposure to silica dust
took part in a recent study to describe the various characteristics of their ailments.
ASBESTOS AND LEAD POISONING GET MOST OF the negative press these days, but silicosis--a lung condition caused by trapped silica dust
particles in the lungs--is coming on strong.
Meanwhile, the Ministry of Labour is saying its review of two years' worth of air-quality data indicates exposure to silica dust
is within acceptable limits.
The first uncertainty is whether the agency will finally, after numerous delays, propose a new health standard for silica dust
. This new standard would include a lower, harder-to-meet, permissible exposure limit (PEL) for silica dust
than the current PEL which is part of "general industry standards." A PEL is a numerical ceiling for particle concentration above which worker exposure is illegal.
The purposes of this study were to measure the extent to which operators of specific heavy equipment types were exposed to respirable silica dust
during disposal pit excavation and to ensure concentrations to which those operators were exposed remained acceptable.
OSHA has been considering issuing a proposed health standard for silica dust
. This would apply to construction companies blasting through rock, be it above or below ground.
According to the ruling medical paradigm of the time, silica dust
was the only source of the miners' respiratory complaints.
"It is these silica dust
particles which cause TB," says Dr Danny Mwila, a physician for the state-owned Zambia Consolidated Copper Mines (ZCCM), which owns all the mines in the province.
Va., showed that freshly cut surfaces of silica dust
harbor copious quantities of free radicals (a class of biologically damaging molecules or molecular fragments that contain an unpaired electron).
The cellulose sorbents are also made from 100% organic fiber and are safe, nontoxic, noncarcinogenic and contain no silica dust
, recycled inks or dioxins.
CARBO ceramic casting media produces no respirable silica dust
, so it complies with OSHA silica dust
permissible exposure limits (PEL) without the need to install expensive environmental engineering controls.