Toxicological and risk issues of soil fumigants are of great concerns for the health and safety of farm workers and the general public residing in the vicinity of fumigated fields. The fumigant chemicals that are potential alternatives to methyl bromide include methyl isothiocyanate (MITC), chloropicrin, 1,3-dichloropropene, and methyl iodide. These compounds have unique physical and chemical properties with implications to dispersion. A brief overview will be given for the toxicological data in the literature for these four fumigants and general processes of mode of entry to biological organisms including intended and non-intended targets. Risks of exposure to these fumigants can be estimated with gas dispersion modeling where environmental variables such as wind speed and direction will be discussed to emphasize the probabilistic nature of exposure risks. Recommendations will be given for reducing the fumigant exposure risk to workers and the general public.