<P> Terry Wade of Texas A&M University, Steven Lohrenz of the University of Southern Mississippi and the Stennis Space Center found evidence of the polycyclic aromatic hydrocarbons (PAH), which are often linked to oil spills, and include carcinogens and chemicals that pose various risks to human health, as deep as 3,300 feet (1.0 km) and as far away as 8 miles (13 km) in May 2010, and said it likely worsened as more oil spilled . The PAHs can kill animals immediately, in high enough concentrations, and can lead to cancer . "From the time that these observations were made, there was an extensive release of additional oil and dispersants at the site . Therefore, the effects on the deep sea ecosystem may be considerably more severe than supported by the observations reported here," the researchers wrote in the journal Geophysical Research Letters . PAH's, they said, include a group of compounds, with different types at different depths . "It is possible they dissipate quickly, but no one has yet showed this". </P> <P> In September 2010, Oregon State University researchers found sharply heightened levels of chemicals in the waters off the coast of Louisiana in August 2010, the last sampling date, even after the well was capped one month prior . Near Grand Isle, Louisiana, the team discovered that PAH remained at levels 40 times higher than before the spill . The PAH's were most concentrated in the area near the Louisiana Coast, but levels also jumped 2 - 3 fold in other spill - affected areas off Alabama, Mississippi and Florida . As of August 2010, PAH levels remained near those discovered while the spill was still flowing heavily . Kim Anderson, a professor of environmental and molecular toxicology, said that based on the findings of other researchers, she suspected that the abundant use of dispersants by BP increased the bio-availability of the PAHs . "There was a huge increase of PAHs that are bio-available to the organisms--and that means they can essentially be uptaken by organisms throughout the food chain ." </P> <P> Dr. Jim Cowan of Louisiana State University's Department of Oceanography and Coastal Sciences, believes PAHs, weathered from leaked oil on the seabed, are likely the cause of the mutations . </P> <P> A 2014 study of the effects of the oil spill on bluefin tuna, published in the journal Science, clarifying the mechanics by which PAH kill fish, found that the toxins from oil spills can cause irregular heartbeats leading to cardiac arrest . It found that PAHs block signaling pathways that allow potassium and calcium ions to flow in and out of cardiac cell membranes and sustain normal heart rates, and that even very low concentrations of crude oil can disrupt these signaling pathways, slowing fish heartbeats . The study found that cardiotoxicity might have been widespread in animal life exposed to the spill . </P>

Who was affected by the bp oil spill