124
Pesticides, Organic Contaminants, and Pathogens in Air
FIGURE 8.1
Structures of top fumigants. MITC is formed in soil from metam sodium, a precursor. Ethyl
formate is a replacement biofumigant and wild mustard mustard is an effective natural
nematicide—both show promise as alternatives to synthetic commercial fumigants. Dazomet
and Metam both release the MITC fumigant in moist soil.
TABLE 8.1
Fumigants in the Top 25 Pesticides Used in California in 2018, Ranked
by Pounds Applied
Rank
Chemical
Pounds
3
1,3-Dichloropropene (1,3-D; Telone)
12,569,270
6
Chloropicrin
7,436,425
10
Metam-sodium a
3,765,705
20
MeBr
1,682,989
Source: California Department of Pesticide Regulation (2018).
a Metam-sodium degrades to the active ingredient MITC.
safety to people and the environment, or at least restricted their use. The
fumigant class has been hit hard in this regard.
Many fumigants are water soluble and as a result can leach into groundwater and ultimately contaminate drinking water. This was the case with
ethylene dibromide (EDB) and dibromochloropropane (DBCP); these stable,
mobile, and potential carcinogens were found in groundwater and thus