Provisional safety study

Following the definition of safety functions, an initial system architecture is proposed. The provisional study aims to verity that this architecture achieves the levels of SIL defined in the PRA. 

The study [LUS 05] begins with an analysis of the sensor-actuator chain relative to each safety function, based on the system architecture. The objective is to identify each component involved in the execution of a safety function. 

The detection of a non-safe position of an tIS Access is done via two ambivalent open door contacts installed on each ttS Access. 

A Failure Mode and Effects Analysis (FMEA) is performed in order to identify the failure modes of each component and the safe and non-safe failures are identified. A failure rate is associated with each mode of failure. In addition, the fault tree technique is applied to the entire architecture in order to analyze common modes and assess the SIL achieved. 

Summary of the provisional safety study for intrusion functions 

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Provisional safety study and collection of safety data... 

The approved color additives appear on positive lists issued by the Food and Drug Administration in the US, the EU, and Japan, but the colorants permitted in each market vary considerably. US and EU regulatory organizations provide provisional and permanent lists of approved color additives. The permanently listed additives are considered safe for use in cosmetic and toiletry products by the regulatory bodies. Provisionally listed color additives are those on which some safety studies are still to be undertaken or their test results are under review. The Japanese regulations include only a permanent list of color additives. 

This study will be conducted in two phases. In the first phase, an identical approach to the provisional safety stndy is performed on the system as bnilt, quantitatively demonstrating that the safety functions are achieved and the safety objectives are met. 

Abbreviations EPA, Environmental Protection Agency ATSDR, Agency for Toxic Substances and Disease Registry FDA Food and Drug Administration NOAEL no-observed-adverse-effect level LOAEL, lowest-observed-adverse-effect level UF, uncertainty factor SF, safety factor RfD, reference dose (an amount of a substance that is anticipated to be without adverse health effects in humans, including sensitive populations, when ingested daily over a lifetime MRL, minimal risk level (an estimate of daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure) pTDI, provisional tolerable daily intake (maximum daily exposure level to a contaminant provisional meaning that it is considered temporary until more data are available, especially the completed Seychelles study) JECFA, Joint FAO/WHO Expert Conunittee on Food Additives pTWl, provisional tolerable weekly intake. 

Department of Health and Human Services, National Institute for Occupational Safety and Health, Division of Surveillance, Hazard Evaluations, and Field Studies (Unpublished provisional data as of 7/1/90). 

Burbower, G.W., "Experimental Data From Consumer Product Safety Commission Studies on the Provisional Rabbit Test," 1973, 5. 

Ochratoxin A was first evaluated by the Committee at its thirty-seventh meeting (Annex 1, reference 94). The key adverse effects noted involved toxicity to the kidney. The Committee established a provisional tolerable weekly intake (PTWI) of 112 ng/kg body weight (bw), on the basis of deterioration of renal function in pigs, for which the lowest-observed-effect level (LOEL) was 8 pg/kg bw per day, and application of a safety factor of 500. At that time, the Committee recommended that further studies be conducted to elucidate the role of ochratoxin A in causing nephropathy in pigs, the mode of action of ochratoxin A as a kidney carcinogen in rodents and the possible role of ochratoxin A in human disease. 

Provisional - AH newly authorised drugs until they have been used fairly extensively in ordinary practice over a period of at least two years. During this period such drugs should be monitored intensively and their safety in ordinary practice proactively studied. 

In 1984 taurine was added to infant formulas, based on at least a decade of studies that included composition, provisional essentiality, safety, and function in mammals (MacLean and Benson, 1989). Nucleotides were added to formulas with both compositional and efficacy claims in the late 1990s. They may act as growth factors and may have immuno-modulating effects on immune defenses (Carver et al., 1991). 

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