Health-based guideline values

For comparison, we have calculated the health effects for typical residential properties (4 occupants each) based on 1) the naturally occurring background radiation levels and radionuclide concentrations in four cities across the U.S. (see Table V) and 2) the EPA (CFR, 1981) guideline values (20 yR/h, 0.02 WL, 5 pCi Ra-226/g of soil) for cleanup at inactive uranium processing sites (see Table VI). 

AIRBORNE EXPOSURE LIMIT (AEL) The permissible airborne exposure concentration for GB for an 6 hour workday or a 40 hour work week is an 8 hour time weight average (TWA) of 0.0001 mg/m3. This value is based on the TWA or GB which can be found in AR 40-8, Occupational Health Guidelines for the Evaluation and Control of Occupational Exposure to Nerve Agents GA, GB, GD, and VX. To date, however, the Occupational Safety and Health Administration (OSHA) has not promulgated a permissible exposure concentration for GB. 

The World Health Organization has determined that there are no adequate data to permit recommendation of a health-based guideline value for ethylene dibromide in drinking-water (WHO, 1993). 

The 1978 Canadian guidelines specify an MAC of 0.02 mg/L for uranium. This value is about 250 times lower than the previous level (5.0 mg/L) specified in the 1968 guidelines and is based primarily upon the results of chronic studies in rats (although the data were considered to be of poor quality). Studies have been initiated in the Environmental Health Directorate to acquire a more accurate data base, and the need to reevaluate uranium once these results are available has been recognized. The preliminary results suggest that the currently specified levels may be unnecessarily stringent. 

Health-based targets for chemicals (e.g, the guideline values in the WHO Guidelines for Drinking-water Quality - WHO, 2004 WHO, 2006) are concentrations that would generally not have a negative health impact if consumed over a lifetime. Therefore, the likelihood of a particular chemical occurring at concentrations that would cause health impacts is the most appropriate indicator that the chemical may be of concern in such situations. 

For individual countries, guideline values are the first step towards establishing specific health-based targets for their particular circumstances, based on local and regional determinants. 

Table A1.1 Chemicals considered for health-based guideline values ... 

In some cases, substances were considered but no guideline value was proposed, because a health-based guideline was not considered appropriate. 

Chlorinated benzenes are widely used in industry and are sometimes encountered in drinking-water from surface sources. They usually give rise to taste and odour problems at concentrations below the health-based guideline value, where one has been proposed. 

Manganese occurs in groundwaters and surface waters that are low in oxygen it often occurs with iron. When it is oxidized in aerobic waters, manganese precipitates as a black slimy deposit, which can build up in distribution to cause severe discolouration at concentrations above about 0.05 mg/L, The health-based guideline value is 0,4 mg/L, Monitoring is only likely to be required for operational reasons where a potential problem has been identified, in which case, final water from the treatment works would normally be the most appropriate sample site. 

The sulfate anion (S042 ) is a common constituent in natural water and is usually present in at least mg/L concentrations. While WHO has decided that it is not necessary to develop a health-based drinking-water guideline value for this anion, concentrations in excess of 500 mg/L sulfate may cause a noticeable taste. 

Tributyltin oxide (TBTO) was widely used as a wood preservative and antifungal agent. It is less widely used now because of its extremely high toxicity to shellfish and its potential impact on the aquatic environment, It has rarely been identified in drinking-water and therefore no health-based guideline value has been proposed. Monitoring would not normally be considered unless a specific problem had been identified. 

Chemicals considered for health-based guideline values Chemicals that may give rise to consumer complaints Chemicals potentially discharged through effluents from industrial sources Association of insecticides and herbicides with crops and crop types... 

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. 

The Bangladesh standard for manganese in drinking water, based on its health effects, is 0.1 mg L" . Some 74% of groundwater samples collected in the NHS exceeded this value and 35% exceeded the provisional WHO guideline value of 0.5 mg L . ... 

These wells derive their water from the Plio-Pleistocene Dupi Tila aquifer which lies beneath the Madhupur Clay. The screened interval of the wells is unknown. The chemical analyses (Table 6) indicate that the groundwater is of low salinity (Na <50 mg L B <0.1 mg L (data not shown) SO4 0.6-35 mg L" ). Concentrations of most trace elements are low to very low. In particular, As concentrations are all <0.5 pg L and P concentrations are less than or equal to 0.1 mg L (data not shown). The low As concentrations are believed to have been confirmed by other more extensive, but unpublished, surveys of Dhaka city water. Dissolved iron concentrations are also low (<0.25 mg L ). Of the measured elements which have WHO health-based guideline values, only Mn has any exceedances one sample had a Mn con-... 

Analysis of seven deep public supply wells from Dhaka city showed that they all contained <0.5 pg L As. These wells also had low concentrations of most other analysed trace elements. Concentrations of Cd, Cr, Pb, Ni, Sb and U were substantially below WHO health-based Guideline values. One of the Dhaka wells exceeded the WHO guideline value (0.5 mg L" ) for Mn. 

The chronic reference dose for di-N-octylphthalate is 0.02 mg kg day No other regulatory or health-based guideline values are currently available for di-N-octylphthalate. Neither the US Environmental Protection Agency nor International Agency for Research on Cancer have evaluated the carcinogenicity of di-N-octylphthalate. 

No exposure guidelines for Agent GA degradation products were found. The estimated oral reference dose for GA for humans is 0.04 qg/kg/day (Opresko et al., 1998). Estimated health-based soil screening values for residential soil range from 1.2 to 3.1 mg/kg of soil (US Army CHPPM, 1999). 

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