There's less lead in the North Atlantic than there was a few decades ago.

Recently, scientists in England were able to measure the presence of lead from natural sources for the first time in 40 years. Over the last four decades, lead contamination from man-made pollution made it impossible to study the natural lead cycle.

Though lead from coal plants and smelting operations continues to leach into the atmosphere and ocean, it's less of an interference.

In the North Atlantic, as much 50 percent of lead measured in ocean samples was found to be from natural sources, like windblown dust.

Though lead isn't an ecological problem in the ocean, its concentrations there have long been used as barometer for man-made pollution on land.

"Lead pollution has never been a hazard to the health of ocean ecosystems, as it occurs in very dilute amounts in seawater," researcher Luke Bridgestock, an Earth scientist and PhD candidate at Imperial College London, explained in a news release. "However, the proportion of lead from human activities and naturally occurring sources in the surface of our oceans reflects the extent of environmental lead pollution."

A reduction in lead pollution has been credited with the phasing out of the metal's use in petroleum products.

"That is why today's find is encouraging," Bridgestock said. "It demonstrates how effective policies to phase out leaded petrol have been."

The findings -- detailed in the journal Nature Communications -- offer proof that policies can affect environmental change, but problems remain. Lead pollution from sources other than automobile exhaust remains high. As well, leaded fuel usage remains a serious environmental threat in other parts of the world.

"This is the first time since similar studies began in the late 1970s that natural lead in the ocean has been at an observable level," said co-author Tina Van de Flierdt, an earth scientist at ICL. "However, this finding is confined to this particular region of the North Atlantic and pollutant lead from industrial processes is still dominant in this ocean and elsewhere. For example, lead pollution in the Indian ocean has increased in recent times due to the economic development of countries surrounding it."