From New York to Baghdad to the Pakistan-Afghanistan border, terror is often associated with bombs, whether they are tied to a human body or implanted in a laser-guided missile.

In China, the kind of fear people feel is much more subtle and much less bloody. It occurs when people shop in wet markets and grocery stores or eat in restaurants or at food stands.

The recent police crackdown on the "gutter oil" ring in Zhejiang, Shandong and Henan provinces is just the latest reminder of such fear. More than 100 tons of "gutter oil" was seized and 32 people were arrested.

"Gutter oil" refers to substandard cooking oil recycled from waste illegally collected from restaurant gutters or sewage drains. It contains carcinogens and other toxins that are harmful to the human body.

Although Professor He Dongping of Wuhan Polytechnic University admitted his estimate that 2 to 3 million tons of "gutter oil" ends up on dinner tables in China each year was an exaggeration, many people feel they constantly run risk of consuming it when dining out.

The scandal came less than two weeks after another major police raid, this time on the production and distribution of clenbuterol, a poisonous chemical known among Chinese as "lean meat powder" and illegally used on pig farms. The Ministry of Public Security said 989 people were rounded up and 2.5 tons of clenbuterol was seized.

Food poisoning caused by clenbuterol-tainted pork has made frequent headlines in recent years. Victims become dizzy, have heart palpitations and sweat profusely. In rare cases, it proves fatal, as it did in Dongguan, Guangdong province, two years ago.

Three years ago the melamine milk powder scandal was uncovered. The tainted milk caused the deaths of several children and made tens of thousands ill.

In April, we had the steamed bun scandal in which a Shanghai food producer was found to be adding coloring to make expired wheat buns look like fresh corn flour buns and black rice buns.

Then there are the cases of excessive pesticide residue detected on fruit and vegetables, excessive additives found in many processed foods and liquor that contains industrial alcohol.

Endless food scandals have prompted many Chinese to question what is still safe to eat.

Unlike bullets and bombs, food tainted with harmful chemicals usually kills people slowly, yet the scale of human suffering is often greater because such food is consumed by the unwitting masses.

The consequences of tainted food is also much worse than bullets and bombs because it has the potential to do harm to future generations.

The recent crackdowns, which came a few months after Premier Wen Jiabao condemned the tainted food cases as a sign of a serious lack of trust and moral degradation in society, are encouraging. However, the people and chemicals caught and seized so far are said to be only a small part of a much larger and complicated network that continues to threaten the nation's food safety.

The crackdown should certainly not repeat the past mistakes of coming fast and leaving fast, so these food safety violators simply wait it out and resume harming consumers afterward.

Our war on food terror should be relentless. We have to demonstrate to the violators that there is zero tolerance for them in our society, our laws and law enforcement. And we should have a surge of at least half a million law enforcement officers to root them all out.

Lowering our guard against food safety violators and showing mercy to such despicable acts would make it impossible to uproot tainted food producers. It only makes us their accomplices.

The author is deputy editor of China Daily US edition based in New York. E-mail: chenwweihua@chinadaily.com.cn