Uh-oh. The China growth story that investors and economists around the world have become accustomed to taking for granted may be running out of steam.

The Chinese economy has slowed down to single-digit percentage growth in recent years, and it could be on the verge of slowing down even more. That isn't what many investors of companies relying on China for growth want to hear, and it's not helping the Chinese markets, either. Hong Kong's Hang Seng (HSIINDICES: ^HSI) fell a whopping 6.4% this past week, part of a long fall that has seen the index plunge to an eight-month low this week. Should you be concerned or is a Chinese economic and market rebound on the way?

Is a trade war brewing?
The Hang Seng has crashed in the past month, shedding nearly 9% since mid-May. Some analysts have called for optimism, noting that average Chinese price-to-earnings ratios remain depressed, but China's economy is the bigger problem.

The country's GDP growth has slowed to below 8%, with the IMF downgrading its full-year projections earlier in the year. It could fall even further: Hong Kong's chief economist at Nomura Securities, Zhiwei Zhang, projected that the country's economic growth could slump to below 7% in the second half of 2013. China will be hard-pressed to support its domestic economic goals with such little growth, particularly as its rapidly growing middle class clamors for higher wages and more benefits.

Protests and other job-related dissatisfaction have swept across China as workers demand better employment conditions. Low-wage jobs helped fuel China's rise in the past few decades as the ubiquitous "Made in China" trend came to dominate low-cost goods, but that era's coming to an end as companies move away from China to cheaper labor sources. It's a bad time for China's job market to have to deal with worker issues: China's long-relied-on trade advantages to boost growth, but its spat with Japan over the Senkaku Islands and its feud with its southern neighbors over South China Sea territorial rights is complicating its relationship with other top economies in the region.

Worse, China's straining its relations with its top export partner, Europe. China boasts a greater trade surplus with the U.S., but the EU takes in more exports from the country than any other nation or bloc. However, a recent and growing trade spat between the two partners is risking that bountiful partnership, and China has few economic friends to rely on already. It can't afford to alienate Europe without risking its economy even further.

That trade dispute is putting pressure on major steelmakers, and ArcelorMittal (MT 0.95%), Europe and the world's largest steel producer, is right in the thick of things. The company's chairman, Lakshmi Mittal, called in the EU last month to launch protectionist measures for the steel industry against Chinese competitors. ArcelorMittal has taken its hits recently, posting a $345 million net loss for 2013's first quarter, and Europe's scrum with China could exacerbate problems for this steel producer in the future -- particularly if China retaliates against any EU action with tariffs of its own, as it has already considered launching against European wine imports.

China's steel industry is still performing well, but infrastructure spending will see pressure as the country's economic growth slides. Guangshen Railway (GSH) may be the best-positioned Chinese infrastructure stock to withstand the issue, as the firm's grown profits handsomely over the recent past and thrives on transporting millions of passengers each year across the large nation. Guangshen's probably safe as a top domestic firm in China that services a desperate need, but watch out especially for foreign companies in China's infrastructure market as spending becomes more selective.