San Diego

Tyrone Hayes: against atrazine. Credit: J. MONE/AP

A California biologist is accusing Minnesota officials of censorship for blocking his conference lecture about environmental damage associated with a popular agricultural herbicide.

Tyrone Hayes of the University of California, Berkeley, says the Minnesota Pollution Control Agency was succumbing to pressure from pro-industry government officials when, late last month, it withdrew an invitation for him to deliver the plenary talk at its Air, Water and Waste Conference next February.

Hayes has published extensively on links between low levels of exposure to the herbicide atrazine and developmental defects in amphibians. He also cites studies linking atrazine to prostate cancer and decreased sperm counts in men. Syngenta, the Swiss-based firm that makes the herbicide, says there is no evidence of environmental damage.

Last year, the Environmental Protection Agency (EPA) re-registered atrazine despite a regulatory review that drew flak from Hayes for relying on too many industry-funded studies. He repeated his criticism on 25 October at a hearing of a committee of Minnesota state representatives, who are considering banning the herbicide.

Sheryl Corrigan, the pollution agency's commissioner, said in a statement that she doubted whether Hayes's research “was the right focus” for the conference. She instructed her staff to withdraw their invitation.

Hayes says that agency officials first asked him to cut the word ‘atrazine’ from his talk, which he refused to do. He adds that they told him that an EPA official “instigated” the “uninvitation” by contacting officials at the Minnesota Department of Agriculture, who then contacted the pollution agency. Agriculture officials acknowledged contacting the agency. EPA officials did not respond to interview requests.

After criticism from environmental groups, the pollution agency reinvited Hayes to give some form of lecture — not a keynote address. But Hayes says he doubts he will attend, because Corrigan blocked her staff from listening to his testimony. Corrigan claims that limiting staff attendance at hearings is routine.