“…Agricultural additives, such as fertilizers, pesticides, 42-44 metals, including zinc (Zn), copper (Cu), 45,46 mercury (Hg), 47,48 and lead (Pb) [49][50][51] are considered sources of exogenous agents that may affect the immune system, the onset of pemphigus, and the environment. Studies have shown that PV patients had three-times greater exposure to pesticides than healthy subjects, and the exposure to metals 52 and pesticide vapors may also be associated with worsening of PV. 43,53,54 A study by Alves et al 55 found high Zn values and significant differences between the waters analyzed in the Pardo River (in Ribeirão Preto upstream and downstream), indicating that the use of fertilizers and other agricultural practices (e.g., burning of sugar cane) exert a significant influence on water quality in this city.…”