SAN FRANCISCO (AP) — Despite long-standing concerns about pesticide exposure, a report issued Tuesday suggests California strawberry growers will have to keep using a contentious set of fumigants to keep the state's $2.3 billion strawberry industry competitive, even as the state ultimately seeks to restrict the chemicals' use. Fumigants are gaseous pesticides that are injected into soil before strawberries and other crops are planted. Methyl bromide, the best known pesticide of this type, was phased out by international treaty because it depletes the Earth's protective ozone layer.