**8. Conclusions**

There are several mineral ores containing transitional atoms with polyhedral bond structure; there is the utilization of minerals of mined mineral ores in the various biotechnology sectors; there is the development of bioengineered nanoparticles for enhanced accumulation and retention effects; there is the bioaccumulation of humanmade synthetic materials including plastic particulates with very slow dissolution

rates and potential for particulate matter environmental toxicity that alter the normal cell molecular mechanisms.

Certain permissible threshold limits are established by the U.S. regulatory agencies for minimizing environmental or occupational exposure to individual mineral constituents measured by mass spectroscopy or by fluoroscopy or to whole particulate matter. Causality for certain mineral exposure-associated toxicity and disease is established by the combined evaluation of *in vitro* test results, animal study experimental data and human epidemiologic findings by probability of significance. Methods that are applied in study design include exposure air sampling by elutriator air flow, characterization of particulate dimensions and shapes by electron microscopy or particle light scattering, measurement of particulate matter dissolution, and biomonitoring of biochemical metabolites in workplace surveillance, gene expression level alterations by cDNA microarray or by RNA sequencing with pre-amplification by qPCR, small animal subject and human blood plasma and tissue imaging with pharmacokinetic modeling, descriptive statistics and epidemiologic -based risk delineation by alternative hypothesis and *p*-value thresholds.

The reasons for particulate matter toxicity can be understood with knowledge of the diversity of topics covered in this chapter on: i) aerosol and particulate matter classes, ii) natural and bioengineered particle types, iii) respiratory tree deposition mechanisms, iv) imperfect particle properties and flow regimes, v) solvation variables, vi) compartmental modeling parameters, and vii) workplace exposure limits and guidelines. The material covered in this chapter will be pertinent to the determination of causal and synergistic relationships for new toxicants and mixtures, and industrial, mining and construction sector exposure air sampling, high-resolution tissue bioimaging and monitoring of general and specific external exposomic effects on DNA and polymorphism and for the further understanding of mechanisms of particulate matter toxicity, and disease initiating and promoting variables.

### **Abbreviations**


