Chlorine chemists and their scientific knowledge helped set the agenda for many environmental problems: PCBs in the Hudson River are polychlorinated biphenols;[9] DDT, dieldrin, and aldrin are chlorinated pesticides; CFCs that deplete the ozone layer are chlorofluorocarbons. Industry actually manufactured the chemicals and consumers purchased them. Therefore, one can determine that chemists are not the sole cause for these issues, but they are not blameless.[10]