share in April, according to filings with the Securities and Exchange Commission. The tech giant did not provide any other details about the investigation. While the ad network serves as Google’s primary money maker, selling $8.3 billion in advertising in the first three months of this year alone, Google said it doesn't believe the potential settlement will have a material adverse effect on its business. The latest disclosure adds to a slew of regulatory and antitrust challenges facing the Mountain View, Calif.-based company. European regulators continue to probe Google over its popular search system, questioning whether the Internet behemoth unfairly manipulates search results to drive advertising sales and fad that investigation resulted in 74 people being detained in 56 cases that were handed to police for possible prosecution. Lead poisoning can damage the nervous, muscular and reproductive systems. Children are particularly at risk. The poisonings in Taizhou were among many in Zhejiang, a major battery production center, and elsewhere in eastern and southern China that appear to have prompted the latest push for better local enforcement of laxly observed environmental standards. "All remediation will be conducted according to strict discipline. Dismantling of illegal smelters and small, unauthorized electroplating workshops will be conducted strictly according to law," the statement cited Cai Xumin, a local official in charge of the Taizhou cleanup, as saying. In Zhejiang's Deqing county, where 53 people were hospitalized after tests in late April found high lead levels in the blood of 332 residents near a factory making lead-acid motorcycle batteries, all three local factories were ordered to stop production, said county public outreach official Ji Huibin. The crackdown is aimed at preventing and reducing contamination of the environment with toxins such as lead, cadmium, mercury, chromium and other heavy metals that have left much of China dangerously polluted. Thousands of children were affected by lead poisoning in several provinces in 2009 and 2010 because they lived near metal smelters or battery factories. Combined with scandals over contaminated foods and milk, the issue has taken on urgency for government leaders who have promised to deliver more sustainable, people-oriented economic growth. Manufacturers of lead-acid batteries are a key target. An explosion in the use of electric scooters and surging auto manufacturing have driven up demand for batteries, but mining, smelting, making and disposal of the lead and the batteries have been poorly regulated. "It doesn't matter what the reason is, companies and local officials must take responsibility for failing to meet e