United States data assessment

Official government statistics on imports and exports for chemicals such as diazinon are summarized under broad generic categories such as pesticides or organophosphates. In 1982, estimated diazinon imports to the United States were 6.41xl04kg (141,000 pounds) (HSDB 1996). No recent estimates are available on the volume of diazinon imported into the United States. Data on past and/or current import volumes are not adequate to assess trends in import volumes of this pesticide. 

The composition of the MS W stream in the United States is assessed each year by the USEPA (compiled by Franklin Associates) based on a materials flow model. The BioCycle Journal (compiled by Columbia University, SC) also reports biennial assessments of the same but is based on data from State reports. Because of differences in methodology and the disparity in items captured in each, the two estimates do not agree and it is difficult to select one as being the better (Tonjes and Greene, 2012). The more popularly quoted data in the literature is by the USEPA and the data for the composition of MSW (USEPA, 2010) are shown in Figure 9.1. 

This monitoring framework should be apphed across broad geographic regions. This book recommends a national or (preferably) continental scale of assessment. The data collected in the United States shonld also be comparable, to the extent feasible and appropriate, with other North American and global mercury monitoring efforts, particularly monitoring of atmospheric transport and deposition. 

Exposure Levels in Humans. Metabolism of endrin in humans is relatively rapid compared with other organochlorine pesticides. Thus, levels in human blood and tissue may not be reliable estimates of exposure except after very high occupational exposures or acute poisonings (Runhaar et al. 1985). Endrin was not found in adipose tissue samples of the general U.S. population (Stanley 1986), or in adipose breast tissue from breast cancer patients in the United States (Djordjevic et al. 1994). Endrin has been detected in the milk of lactating women (Alawi et al. 1992 Bordet et al. 1993 Dewailly et al. 1993), but no data from the United States could be located. Data on the concentrations of endrin in breast milk from U.S. women would be useful. No information was found on levels of endrin, endrin aldehyde, or endrin ketone in blood and other tissues of people near hazardous waste sites. This information is necessary for assessing the need to conduct health studies on these populations. 

Reliable monitoring data for the levels of cyanide and thiocyanate in contaminated media at hazardous waste sites are needed so that the information obtained on levels of cyanide and thiocyanate in the environment can be used in combination with the known body burdens of cyanide and thiocyanate to assess the potential risk of adverse health effects in populations living in the vicinity of hazardous waste sites. Also, there is a need for data relating to exposure levels of cassava eaters in the United States. 

Regulators in the United States and in Europe, and other public health institutes, appear to have found UF refinements such as those proposed by Renwick to be valuable additions to the risk assessment model for threshold agents, and we should not be surprised to see many examples in the future in which data are judged sufficient to replace the default UFs in just the way we have described. 

Bioavailability from Environmental Media. No information on the presence of 3,3 -dichloro-benzidine in foods was located in the available literature. The Canadian Government s Priority Substances List Assessment Report for 3,3 -dichlorobenzidine (Government of Canada 1993) also reports that no data on the levels of 3,3 -dichlorobenzidine in drinking water or foodstuffs were identified within either Canada or the United States. Because 3,3 -dichlorobenzidine has been found to bind strongly to soil constituents (Berry and Boyd 1985 Chung and Boyd 1987), Law (1995) concluded that it would also bind strongly to sedimentary material in the marine aquatic environment and thus may have limited bioavailability. 

At the present time, several countries have well-organised and experienced spontaneous reporting systems which contribute the bulk of ADE reports. In particular the United States, the United Kingdom, France and the Scandinavian countries have records going back several decades, and can claim to have in their possession data of reasonable quality. The section on p. 438 considers the various methods of causality assessment that are available and the data that are required for their application. 

Another approach to risk-based decision-making is the precautionary principle. The risk assessment and risk management approach used in the United States places a heavy reliance on the certainty of the data. The precautionary principle emphasizes that there is always some uncertainty and that decisions should be based on recognizing the possibility of harm. When in doubt, be cautious until adequate data are available to show that there is little potential for harm. Action to reduce exposure to hazardous agents should begin even if there is some uncertainty in the data. 

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