Occupational Exposure Respiratory Standard

Inhalation of crystalline or fused vitreous silica dust, usually overlong periods, causes a disabling, progressive pulmonary disease known as silicosis (84). Amorphous siUcas have not been linked to siUcosis (85), but can cause respiratory irritation. The history and poHtics of siUcosis have been reviewed (86). Standards have been set or recommended for occupational exposures (87,88) and review articles on the health effects of siUca are available (83,89). 

Lead Standard (29 CFR 1910.1025). Since colorant and additive production involves the use of lead compounds, the lead standard (29 CFR 1910.1025) becomes important. This standard applies to all occupational exposures to lead and lead compounds and requires respiratory protection when workplace exposure levels for lead reaches or exceeds 5 pg/m ... 

Various standards and guidelines have been developed for sulfur mustard. These values are applieable to occupational exposures, emergeney planning and response efforts, and remediation efforts. Airborne exposure limits (AELs) and health-based environmental sereening levels (HBESLs) for sulfur mustard have been developed by the US Army (USACHPPM, 1999, 2000). Most health-based criteria for sulfur mustard vapor exposure are based upon protection of the eyes and respiratory traet whieh are the most sensitive targets. 

Occupational exposure to chromium(VI) compounds has been related to an increased risk of lung cancer. Several hexavalent compounds of chromium, including chromium trioxide, are hsted in lARC Group 1 ("carcinogenic to humans") and are classified as "select carcinogens" under the criteria of the OSHA Laboratory Standard. Long-term exposure to chromium trioxide or chromium(VI) salts may cause ulceration of the respiratory system and skin. Exposure to chromium trioxide by inhalation or skin contact may lead to sensitization. Chromium trioxide has exhibited teratogenic activity in animal tests. 

The primary hazard with crystalline silica is the development of silicosis due to the inhalation of fine particles (<10 pm). There are reports that the exposure to silica (or the existence of silicosis) is associated with an increase in the incidence of lung cancer the International Agency for Research on Cancer classifies silica in Group 2A probably carcinogenic to humans . The applicable governmental regulations in various countries should be consulted and followed. Also, various codes of practice, such as ASTME 1132 [28], Standard Practice for Health Requirements Relating to Occupational Exposure to Silica, and ANSI Z 88.2 [29], Practices for Respiratory Protection, may be consulted. 

Occupational inhalation exposures occur during the handling of coke, charcoal, and activated earbon, but there is little information on concentrations and sizes of the suspended particles. There are no exposure standards for these materials, aside from nonspecific dust standards, although there are standards for coal tar pitch (10). Similar to other dusts, these materials may cause transient reductions of lung function or aggravation of other respiratory symptoms on brief, high-level exposure. Pneumoconiosis from coke or charcoal dust is possible with heavy exposures, but little information has been reported. Pneumoconiosis has been reported in workers manufacturing carbon electrodes from coke (77) and from occupational exposures to activated carbon (78). 

Workers who mine and process mineral sands containing tin and associated trace metals can also be exposed to uranium and thorium dusts from the sands (252). In a United Nations-sponsored study of radiological exposures in the tin by-product industry in Southeast Asia, Hewson found that many of these exposures are above occupational exposure limits, but could easily be reduced by use of standard radiation protection practices involving ventilation and respiratory protection. Implementation of such practices may be difficult, however, because most of the estimated 2000 workers employed in this indnstry work in plants that employ fewer than 20 workers, with many plants employing fewer than 5 workers. 

It is good practice to keep concentrations of airborne nickel in any chemical form as low as possible and certainly below the relevant standard. Local exhaust ventilation is the preferred method, particularly for powders, but personal respirator protection may be employed where necessary. In the United States, the Occupational Safety and Health Administration (OSHA) personal exposure limit (PEL) for all forms of nickel except nickel carbonyl is 1 mg/m. The ACGIH TLVs are respectively 1 mg/m for Ni metal, insoluble compounds, and fume and dust from nickel sulfide roasting, and 0.1 mg/m for soluble nickel compounds. The ACGIH is considering whether to lower the TLVs for all forms of nickel to 0.05 mg/m, based on nonmalignant respiratory effects in experimental animals. 

In contrast to the documented effect of cotton dust on acute responses, the causation of chronic respiratory effects in occupationally exposed subjects has not been established. The OSHA cotton dust standard is based on the premise that sustained exposure may result in chronic respiratory problems. To test this hypothesis, the pertinent literature is reviewed and discussed in an attempt to decide if convincing epidemiological documentation exists to support a cause and effect connection between prolonged dust exposure and chronic respiratory impairment. There appears to be a need for additional studies to clarify this important aspect of occupational medicine. 

A few studies have reported an association between bladder and renal cancers and occupations having the potential for exposures to asphalt. In an historical cohort study of 1320 workers in the asphalt industry, there was a significant increase in brain cancer [standardized mortality ratio (SMR) 500] but not in respiratory, bladder, or gastrointestinal cancer. Of 679 Danish men who were heavily exposed to asphalt, significant increases occurred in the incidences of cancer of the mouth (SMR 1111), esophagus (698), rectum (318), and lung (344). ... 

Material safety data sheets (MSDS) must be accessible to employees in their work areas by federal law and are frequently useful for determining the most likely agent(s) responsible for inducing respiratory disease (Bernstein, JA, 1992). Industrial hygienists, who routinely perform air sampling measurements in the workplace in compliance with established standards (e.g. National Institute for Occupational Safety and Health (NIOSH)), are often helpful in providing information about exposure levels of specific agents (Bernstein, JA, 1992). 

IDLH is intended to provide guidance for determining respiratory protection requirements in occupational environments it is not necessarily suitable for emergency planning and risk assessment. However, IDLH information is often the only form of exposure information available. IDLH values are often found in MSDS and in standard references. Some practitioners use a value of lDLH/10 as a working number for defining acceptable risk. 

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