Human health, viii

The interpretation of the effects of such drift, particularly its potential for adverse effects on human health, is dependent on some of the parameters of environmental behavior shown on Table VIII. The dose is given at 2 lbs/acre and translated into a deposit level of 20 mg/square foot, which is more useful in the interpretation of exposure data. The figures given for the deposit amount from spray drift at 100 yards and 1/2 mile are the figures for drift from a coarse spray on flat land for small target areas and are average drift amounts. The figure of 20 mg/kg is the NOEL for 2,4-D. 

Chemical standards are widely used to protect the environment and human health from substances released by human activity. Generally, standards relate to doses or concentrations in the environment for specific chemicals, below which unacceptable effects are not expected to occur. Many standards are legally enforceable numerical limits, such as Environmental Quality Standards for List 1 chemicals in water or Annex X and VIII standards under the European Water Framework Directive. Others are not mandatory but are contained in guidelines, codes of practice, or sets of criteria for deciding individual cases. Some standards are not set by governments but carry authority for other reasons, especially the scientific eminence or market power of those who set them (e.g., World Health Organization guidelines). 

Figure 1. Frequencies of compounds, in eleven chemical classes, that have been deleted from the RCRA Appendix VIII list partially due to limitations in analytical capabilities, compared to frequencies of compounds in these same chemical classes that are considered to have a potential impact upon human health.

It contains any of the toxic constituents listed in Appendix VIII (in 40 CFR 261), unless after considering any of the following factors, the Administrator concludes that the waste is not capable of posing a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of or otherwise managed ... 

With respect to wastewater generation, there are a few scenarios with low impact (III, IV, VI and VIII) while the rest exhibit very similar values. If all aspects are analysed simultaneously, the best alternatives are scenarios m and IV, while the worst one is scenario VII. It is noteworthy to say that all environmental loads considered in the eco-vector have to be balanced to reach a compromise, as their impacts in the ecosystem and human health differ widely. Also, note that some of the impacts are local (e.g. steam production), while others are distributed in different regions (e.g. extraction, external electricity generation) even though the LCA approach does not allow to differentiate among them. 

NTP. 1994. Seventh annual report on carcinogens. Summary 1994. U.S. Department of Health and Human Services, iv-viii, 226-229. 

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