Health effects classification and its role in the derivation of minimal risk levels: neurological effects

Possible food safety hazards of ready-to-eat raw fish containing product (sushi, sashimi)

It is undeniable that with the popularity of sushi and sashimi over the last decade the consumption of raw fish has extremely increased. Raw fish is very appreciated worldwide and has become a major component of human diet because of its fine taste and nutritional properties. Possible hazards concerning fish safety and quality are classified as biological and chemical hazards. They are contaminants that often accumulate in edible tissue of fish and transmit to humans via the food chain affecting the consumer's health. Although their concentration in fish and fishery products are found at non-alarming level of a daily basis period, they induce hazardous outcome on human health due to long and continuous consumption of raw fish. Regular sushi and sashimi eaters have to be aware of the contaminants found in the other components of their dish that often add up to acceptable residue limits found in fish. Hence, there is the urge for effective analytical methods to be developed as well as stricter regulations to be put in force between countries to monitor the safety and quality of fish for the interest of public health.

Health effects classification and its role in the derivation of minimal risk levels: Renal effects

The Agency for Toxic Substances and Disease Registry (ATSDR) derives minimal risk levels (MRLs) for priority hazardous substances. MRLs are health guidance values intended to serve as screening levels for health assessors to select contaminants of concern and to assess potential health effects at hazardous waste sites and areas affected by unplanned releases. Current MRLs are published in ATSDR toxicological profiles and are listed at the ATSDR website at . To date, ATSDR has derived 125 inhalation MRLs, 207 oral MRLs, and eight external radiation MRLs; 19 MRLs are based on renal effects. This article reports on endpoints used to derive the MRLs. It also presents the ranking of effects into less serious and serious categories as described in ATSDR's Guidance for Developing Toxicological Profiles.

Health effects classification and its role in the derivation of minimal risk levels: Hepatic effects

The Agency for Toxic Substances and Disease Registry (ATSDR) derives health based guidance values called minimal risk levels (MRLs) to assist with assessment of risks posed by exposures to hazardous chemicals. Current MRLs are posted on ATSDR's web site (www.atsdr.cdc.gov). From the total 326 MRLs currently posted, 79 MRLs are based on hepatic endpoints. The paper reports on endpoints used for the derivation of these MRLs and the use of uncertainty factors. It also describes the ranking of effects into less serious and serious categories as described in ATSDR's Guidance for Developing Toxicological Profiles.

Health effects classification and its role in the derivation of minimal risk levels: Reproductive and endocrine effects

The Agency for Toxic Substances and Disease Registry (ATSDR) derives health-based guidance values called minimal risk levels (MRLs) to assist with assessment of risks posed by exposures to hazardous chemicals. From the total of 326 MRLs currently posted on ATSDR's web site (www.atsdr.cdc.gov), 14 and 5 MRLs are based on reproductive and endocrine endpoints, respectively. The paper also describes the ranking of effects into less serious and serious categories according to ATSDR's Guidance for Developing Toxicological Profiles, endpoints used for the MRLs derivation, and the use of uncertainty factors.

Considerations and procedures in the derivation of ATSDR minimal risk levels

Minimal risk levels (MRLs) are health-based guidance values derived for individual substances by conducting a thorough review of the literature, identifying appropriate target organs of response, and identifying a dose level where a no adverse effect or the lowest adverse effect level is seen. This level is then evaluated for uncertainty in the data base and for other extenuating factors and subsequently adjusted with uncertainty or modifying factors. The resulting calculation yields the MRL that is defined as an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure. Typically, MRLs are derived for different durations of exposure (acute, intermediate, chronic) and for different routes of exposure (oral, inhalation). The MRLs serve as useful reference values in evaluating human health from exposure to substances found at hazardous waste sites. Because of numerous requests of various programs, recent work has focused on expanding the applicability of MRLs to other situations and routes of exposure (dermal, food supply, intramuscular) beyond the traditional oral and inhalation exposure routes at waste sites. Results of work, in conjunction with the Agency for Toxic Substances and Disease Registry's computational toxicology laboratory, shows that the use of computational methods, such as physiologically based pharmacokinetic modeling, may allow the MRL process to be adapted to unique durations and routes of exposure such as intramuscular injections.

Public health assessment of hexachlorobenzene

Recently, hexachlorobenzene (HCB) was proposed for inclusion in the system of toxicity equivalency factors (TEFs) currently used for dioxin-like compounds. In this paper, we explore the practical implications of the proposition to the Agency for Toxic Substances and Disease Registry (ATSDR) programs by comparing respective health guidance values for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and HCB (expressed as total toxicity equivalents [TEQs]), reviewing possible interactions between HCB and dioxin-like chemicals, and by providing information on actual co-existence of HCB and dioxin-like chemicals at hazardous waste sites. We found a good correlation between the TEF-adjusted oral exposure guidance values for HCB and guidance values for TCDD. The combination of HCB and other dioxin-like compounds was not found in soil, air, or water media at hazardous waste sites. Based on this fact, it is not necessary to include HCB in the total TEQ count at hazardous waste sites at this time.